NetLogo 6.0 User Manual

TheNetLogo6.0.2UserManual

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TableofContents

TableofContentsWhatisNetLogo?

FeaturesCopyrightandLicenseInformation

HowtoreferenceAcknowledgmentsNetLogolicenseCommerciallicensesNetLogoUserManuallicenseOpensourceThirdpartylicenses

ScalaMersenneTwisterFastColtConfigApacheCommonsCodec(TM)FlexmarkJHotDrawJOGLMatrix3DASMLog4jPicoContainerParboiledRSyntaxTextAreaJCodecJava-Objective-CBridgeWebcam-captureGuavaGephiRExtensionJNA

What'sNew?Version6.0.2(August2017)

FeatureChangesBugfixesExtensionChangesDocumentationChangesModelChanges

Version6.0.1(March2017)FeatureChangesBugfixesExtensionChangesDocumentationChangesModels

Version6.0(December2016)FeatureChangesBugfixesLanguageChangesExtensionChangesOperatingSystemSupportDocumentationChangesInternationalizationChangesModels

Version5.3.1(February2016)FeatureChangesExtensionChanges

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BugfixesVersion5.3(December2015)

FeatureChangesExtensionChanges

Version5.2.1(September2015)ExtensionsNewfeaturesBugfixesModelchanges

Version5.2.0(April2015)ExtensionsNewfeaturesBugfixesModelchanges

Version5.1.0(July2014)Version5.0.4(March2013)Version5.0(February2012)Version4.1.3(April2011)Version4.1(December2009)Version4.0(September2007)Version3.1(April2006)Version3.0(September2005)Version2.1(December2004)Version2.0.2(August2004)Version2.0(December2003)Version1.3(June2003)Version1.2(March2003)Version1.1(July2002)Version1.0(April2002)

SystemRequirementsApplicationRequirements

WindowsMacOSXLinux

3DRequirements32-bitor64-bit?

ContactingUsWebsiteFeedback,questions,etc.ReportingbugsOpensource

SampleModel:PartyAtaPartyChallengeThinkingwithmodelsWhat'snext?

Tutorial#1:ModelsSampleModel:WolfSheepPredationControllingtheModel:ButtonsControllingspeed:SpeedSliderAdjustingSettings:SlidersandSwitchesGatheringInformation:PlotsandMonitors

PlotsMonitors

ControllingtheView

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ModelsLibrarySampleModelsCurricularModelsCodeExamplesHubNetActivities

What'sNext?Tutorial#2:Commands

SampleModel:TrafficBasicCommandCenterWorkingwithcolorsAgentMonitorsandAgentCommandersWhat'sNext?

Tutorial#3:ProceduresAgentsandproceduresMakingthesetupbuttonSwitchingtotick-basedviewupdatesMakingthegobuttonExperimentingwithcommandsPatchesandvariablesTurtlevariablesMonitorsSwitchesandlabelsMoreproceduresPlottingTickcounterSomemoredetailsWhat'snext?Appendix:Completecode

InterfaceGuideMenus

Chart:NetLogomenusTabsInternationalUsage

CharactersetsLanguagesSupportfortranslators

InterfaceTabGuideWorkingwithinterfaceelementsChart:InterfaceToolbarThe2Dand3Dviews

Manipulatingthe3DViewCommandCenter

ReportersAccessingpreviouscommandsClearingArranging

PlotsPlotPens

SlidersAgentMonitors

InfoTabEditingHeadings

Input

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ParagraphsExampleFormatted

ItalicizedandboldtextExampleFormatted

OrderedlistsExampleFormatted

UnorderedlistsExampleFormatted

LinksAutomaticlinksLinkswithtextLocallinks

ImagesExampleFormattedLocalimages

BlockquotationsExampleFormatted

CodeExampleFormatted

CodeblocksExampleFormatted

SuperscriptsandsubscriptsExampleFormatted

NotesonusageOtherfeatures

CodeTabGuideIncludedFilesMenuAutomaticindentation

ProgrammingGuideAgentsProceduresVariablesTickcounter

WhentotickFractionalticks

ColorsAskAgentsets

SpecialagentsetsAgentsetsandlists

BreedsLinkbreeds

ButtonsListsMathRandomnumbers

AuxiliarygeneratorLocalrandomness

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TurtleshapesLinkshapesViewupdates

ContinuousupdatesTick-basedupdatesChoosingamodeFramerate

PlottingPlottingpointsPlotcommandsOtherkindsofplotsHistogramsClearingandresettingRangesandautoscalingUsingaLegendTemporaryplotpensset-current-plotandset-current-plot-penConclusion

StringsOutputFileI/OMoviesPerspectiveDrawingTopologyLinksAnonymousprocedures

AnonymousprocedureprimitivesAnonymousprocedureinputsAnonymousproceduresandstringsConcisesyntaxAnonymousproceduresasclosuresNonlocalexitsAnonymousproceduresandextensionsLimitationsWhatisOptional?Codeexample

Ask-ConcurrentUserInteractionPrimitives

Whatdoes"Halt"mean?TieMultiplesourcefilesSyntax

ColorsNoticeKeywordsIdentifiersScopeCommentsStructureCommandsandreportersComparedtootherLogos

TransitionGuideChangesforNetLogo6.0

TasksreplacedbyAnonymousProceduresLinkreportersoverhauledtobemoreconsistentandflexibleRemovalofAppletsChangestotheNetLogoUserInterfaceNobodyNotPermittedasaChooserValue

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BreedsmusthavesingularandpluralnamesRemovalof"Movie"PrimsImprovedNameCollisionDetectionRemovalofhubnet-set-client-interfaceImproved&UpdatedExtensionsAPIAddrangeprimitive

ChangesforNetLogo5.2hsbprimitivesGoGoextension

ChangesforNetLogo5.0PlottingTickcounterUnicodecharactersInfotabsModelspeedListperformanceExtensionsAPI

ChangesforNetLogo4.1Combiningsetandof

ChangesforNetLogo4.0WhonumberingTurtlecreation:randomizedvs."ordered"AddingstringsandlistsThe-atprimitivesLinksNew"of"syntaxSerialaskTickcounterViewupdatemodesSpeedsliderNumbersAgentsetbuildingRGBColorsTie

ChangesforNetLogo3.1AgentsetsWrappingRandomturtlecoordinates

ShapesEditorGuideGettingstarted

ImportingshapesCreatingandeditingturtleshapes

ToolsPreviewsOverlappingshapesUndoColorsOtherbuttonsShapedesignKeepingashape

CreatingandeditinglinkshapesChanginglinkshapeproperties

UsingshapesinamodelBehaviorSpaceGuide

WhatisBehaviorSpace?WhyBehaviorSpace?

HowItWorksManagingexperimentsetupsCreatinganexperimentsetupSpecialprimitivesforBehaviorSpaceexperiments

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RunninganexperimentAdvancedusage

RunningfromthecommandlineSettingupexperimentsinXMLAdjustingJVMParametersControllingAPI

SystemDynamicsGuideWhatistheNetLogoSystemDynamicsModeler?

BasicConceptsSampleModels

HowitWorksDiagramTabCodeTabTheSystemDynamicsModelerandNetLogo

Tutorial:Wolf-SheepPredationStep1:SheepReproductionStep2:NetLogoIntegrationStep3:WolfPredation

HubNetGuideUnderstandingHubNet

NetLogoHubNetArchitecture

ComputerHubNetActivitiesClientsRequirementsStartinganactivityHubNetControlCenterTroubleshootingKnownLimitations

TeacherworkshopsHubNetAuthoringGuideRunningHubNetinheadlessmodeGettinghelp

HubNetAuthoringGuideCodingHubNetactivities

SetupReceivingmessagesfromclientsSendingmessagestoclientsExamples

HowtomakeaclientinterfaceViewupdatesontheclientsClickingintheviewonclientsCustomizingtheclient'sviewPlotupdatesontheclients

ModelingCommonsGuideIntroductionModelingCommonsAccountsUploadingModels

UploadANewModelUploadAChildOfAnExistingModel("forking")UpdatingAnExistingModel

LoggingStartinglogging

MacOSXorWindowsLinuxandothers

Usinglogging

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WherelogsarestoredHowtoconfiguretheloggingoutput

AdvancedConfigurationControllingGuideMathematicaLink

Whatisit?WhatcanIdowithit?InstallationUsageKnownIssuesSourcecodeCredits

NetLogo3DIntroduction

3DWorldsTheobserverandthe3DviewCustomShapes

TutorialStep1:DepthStep2:TurtleMovementStep3:ObserverMovement

DictionaryCommandsandReportersBuilt-InVariablesPrimitivesat-points4.1distancexyz4.1distancexyz-nowrap4.1dz4.1facefacexyz4.1left4.1link-pitch4.1.2load-shapes-3d4.1max-pzcor4.1min-pzcor4.1neighbors4.1neighbors64.1orbit-down4.1orbit-left4.1orbit-right4.1orbit-up4.1__oxcor__oycor__ozcorpatch4.1patch-at4.1patch-at-heading-pitch-and-distance4.1pitchpzcorrandom-pzcor4.1random-zcor4.1right4.1rollroll-left4.1roll-right4.1setxyz4.1tilt-down4.1tilt-up4.1towards-pitch4.1towards-pitch-nowrap4.1towards-pitch-xyz4.1towards-pitch-xyz-nowrap4.1turtles-at4.1<breeds>-atworld-depth4.1zcorzoom4.1

ExtensionsGuideUsingExtensions

Whereextensionsarelocated

NetLogoArduinoExtension

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UsingNotesCompatibilityQuestions

Primitivesarduino:primitivesarduino:portsarduino:openarduino:closearduino:getarduino:write-stringarduino:write-intarduino:write-bytearduino:is-open?

NetLogoArrayExtensionUsing

WhentoUseExampleuseofArrayExtension

Primitivesarray:from-listarray:itemarray:setarray:lengtharray:to-list

NetLogoBitmapExtensionUsing

WhatdoestheBitmapExtensiondo?Gettingstarted

Primitivesbitmap:average-colorbitmap:channelbitmap:copy-to-drawingbitmap:copy-to-pcolorsbitmap:difference-rgbbitmap:exportbitmap:from-viewbitmap:to-grayscalebitmap:heightbitmap:importbitmap:scaledbitmap:width

NetLogoCfExtensionUsingCasesPrimitives

cf:whencf:selectcf:matchcf:matchingcf:casecf:case-iscf:else

NetLogoCsvExtensionCommonusecasesandexamples

ReadafileallatonceReadafileonelineatatimeReadafileonelinepertickWriteafile

Primitives

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FormattingNetLogodataasCSVParsingCSVinputtoNetLogodatacsv:from-rowcsv:from-stringcsv:from-filecsv:to-rowcsv:to-stringcsv:to-file

NetLogoGisExtensionUsing

HowtouseKnownIssuesCredits

PrimitivesRasterDatasetPrimitivesDatasetPrimitivesVectorDatasetPrimitivesCoordinateSystemPrimitivesDrawingPrimitivesgis:set-transformationgis:set-transformation-dsgis:set-world-envelopegis:set-world-envelope-dsgis:world-envelopegis:envelope-ofgis:envelope-union-ofgis:load-coordinate-systemgis:set-coordinate-systemgis:load-datasetgis:store-datasetgis:type-ofgis:patch-datasetgis:turtle-datasetgis:link-datasetgis:shape-type-ofgis:property-namesgis:feature-list-ofgis:vertex-lists-ofgis:centroid-ofgis:location-ofgis:property-valuegis:find-featuresgis:find-one-featuregis:find-less-thangis:find-greater-thangis:find-rangegis:property-minimumgis:property-maximumgis:apply-coveragegis:coverage-minimum-thresholdgis:set-coverage-minimum-thresholdgis:coverage-maximum-thresholdgis:set-coverage-maximum-thresholdgis:intersects?gis:contains?gis:contained-by?gis:have-relationship?gis:relationship-ofgis:intersectinggis:width-ofgis:height-ofgis:raster-valuegis:set-raster-value

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gis:minimum-ofgis:maximum-ofgis:sampling-method-ofgis:set-sampling-methodgis:raster-samplegis:raster-world-envelopegis:create-rastergis:resamplegis:convolvegis:apply-rastergis:drawing-colorgis:set-drawing-colorgis:drawgis:fillgis:paintgis:import-wms-drawing

NetLogoGogoExtensionUsageChangesPrimitives

OtherOutputsUtilitiesGeneralSensorsOutputsandServosgogo:primitivesgogo:howmany-gogosgogo:talk-to-output-portsgogo:set-output-port-powergogo:output-port-ongogo:output-port-offgogo:output-port-clockwisegogo:output-port-counterclockwisegogo:set-servogogo:ledgogo:beepgogo:read-sensorsgogo:read-sensorgogo:read-allgogo:send-bytes

NetLogoLsExtensionLevelSpacefundamentals

HeadlessandInteractiveModelsKeepingTrackofModelsAgeneralusecase:AskingandReportingAgeneralusecase:Inter-ModelInteractionsAgeneralUsecase:Tidyingup“Dead”ChildModels

CitingLevelSpaceinResearchPrimitives

CommandingandReportingLogicandControlOpeningandClosingModelsls:create-modelsls:create-interactive-modelsls:closels:resetls:askls:ofls:reportls:withls:let

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ls:modelsls:showls:show-allls:hidels:hide-allls:path-ofls:name-ofls:model-exists?

NetLogoMatrixExtensionUsing

WhentoUseHowtoUseExample

PrimitivesMatrixcreationandconversionto/fromlistsAdvancedfeaturesMatrixdataretrievalandmanipulationMathoperationsmatrix:make-constantmatrix:make-identitymatrix:from-row-listmatrix:from-column-listmatrix:to-row-listmatrix:to-column-listmatrix:copymatrix:pretty-print-textmatrix:getmatrix:get-rowmatrix:get-columnmatrix:setmatrix:set-rowmatrix:set-columnmatrix:swap-rowsmatrix:swap-columnsmatrix:set-and-reportmatrix:dimensionsmatrix:submatrixmatrix:mapmatrix:times-scalarmatrix:timesmatrix:*matrix:times-element-wisematrix:plus-scalarmatrix:plusmatrix:+matrix:minusmatrix:-matrix:inversematrix:transposematrix:real-eigenvaluesmatrix:imaginary-eigenvaluesmatrix:eigenvectorsmatrix:detmatrix:rankmatrix:tracematrix:solvematrix:forecast-linear-growthmatrix:forecast-compound-growthmatrix:forecast-continuous-growthmatrix:regress

NetLogoNwExtensionUsage

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SpecialagentsetsvsnormalagentsetsAnoteregardingfloatingpointcalculationsPerformancePrimitives

GeneratorsPathandDistanceClusterer/CommunityDetectionContextManagementImportandExportCentralityMeasuresClusteringMeasuresnw:set-contextnw:get-contextnw:with-contextnw:turtles-in-radiusnw:turtles-in-reverse-radiusnw:distance-tonw:weighted-distance-tonw:path-tonw:turtles-on-path-tonw:weighted-path-tonw:turtles-on-weighted-path-tonw:mean-path-lengthnw:mean-weighted-path-lengthnw:betweenness-centralitynw:eigenvector-centralitynw:page-ranknw:closeness-centralitynw:weighted-closeness-centralitynw:clustering-coefficientnw:modularitynw:bicomponent-clustersnw:weak-component-clustersnw:louvain-communitiesnw:maximal-cliquesnw:biggest-maximal-cliquesnw:generate-preferential-attachmentnw:generate-randomnw:generate-watts-strogatznw:generate-small-worldnw:generate-lattice-2dnw:generate-ringnw:generate-starnw:generate-wheelnw:save-matrixnw:load-matrixnw:save-graphmlnw:load-graphmlnw:loadnw:save

NetLogoPaletteExtensionUsingthePaletteExtensionGettingStarted

WhatcolorsshouldIuse?ShouldIuseacontinuouscolorgradientorjustadiscretecolorset?ExampleModelsFurtherReading

Primitivespalette:scale-gradientpalette:scale-schemepalette:scheme-colorspalette:scale-gradient

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ReferencesNetLogoProfilerExtension

UsingtheProfilerExtensionHowtouseExample

Primitivesprofiler:callsprofiler:exclusive-timeprofiler:inclusive-timeprofiler:startprofiler:stopprofiler:resetprofiler:report

NetLogoRExtensionUsing

SomeTipsInstalling

InstallingRConfiguringtheRextensionDeterminingr.homeandjri.home.paths

Primitivesr:clearr:clearLocalr:evalr:__evaldirectr:gcr:getr:interactiveShellr:putr:putagentr:putagentdfr:putdataframer:putlistr:putnamedlistr:setPlotDevicer:stop

TroubleshootingLoadingRpackagesfailsAfterchangingtheworkingdirectoryinR(e.g.withsetwd())NetLogodoesn’tfindtheextensionSpecificerrorcodelist

CitationCopyrightandLicense

NetLogoRndExtensionUsageAnoteaboutperformancePrimitives

AgentSetPrimitivesListPrimitivesrnd:weighted-one-ofrnd:weighted-n-ofrnd:weighted-n-of-with-repeatsrnd:weighted-one-of-listrnd:weighted-n-of-listrnd:weighted-n-of-list-with-repeats

NetLogoSoundExtensionUsing

HowtoUseMIDIsupport

Primitives

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sound:drumssound:instrumentssound:play-drumsound:play-notesound:play-note-later

DrumNamesInstrumentNames

NetLogoTableExtensionUsing

WhentoUseExampleManipulatingTablesKeyRestrictions

Primitivestable:cleartable:countstable:group-agentstable:group-itemstable:from-listtable:gettable:get-or-defaulttable:has-key?table:keystable:lengthtable:maketable:puttable:removetable:to-listtable:values

NetLogoVidExtensionConcepts

VideoSourceSourceLifecycleVideoRecorder

Primitivesvid:camera-namesvid:camera-openvid:camera-selectvid:movie-selectvid:movie-openvid:movie-open-remotevid:closevid:startvid:stopvid:statusvid:capture-imagevid:set-timevid:show-playervid:hide-playervid:record-viewvid:record-interfacevid:record-sourcevid:recorder-statusvid:start-recordervid:save-recording

NetLogoView2.5dExtensionHowtoUse

IncorporatingIntoModelsFeedback

Primitives

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view2.5d:patch-viewview2.5d:decorate-patch-viewview2.5d:undecorate-patch-viewview2.5d:turtle-viewview2.5d:update-all-patch-viewsview2.5d:update-patch-viewview2.5d:update-turtle-viewview2.5d:get-z-scaleview2.5d:set-z-scaleview2.5d:set-turtle-stem-thicknessview2.5d:get-observer-anglesview2.5d:set-observer-anglesview2.5d:get-observer-xy-focusview2.5d:set-observer-xy-focusview2.5d:get-observer-distanceview2.5d:set-observer-distanceview2.5d:remove-patch-viewview2.5d:remove-turtle-viewview2.5d:remove-all-patch-viewsview2.5d:remove-all-turtle-viewsview2.5d:count-windows

FAQ(FrequentlyAskedQuestions)Questions

GeneralDownloadingRunningUsageProgrammingBehaviorSpaceNetLogo3DExtensions

GeneralWhyisitcalledNetLogo?HowdoIciteNetLogoorHubNetinapublication?HowdoIciteamodelfromtheModelsLibraryinapublication?WhereandwhenwasNetLogocreated?WhatprogramminglanguagewasNetLogowrittenin?What'stherelationshipbetweenStarLogoandNetLogo?UnderwhatlicenseisNetLogoreleased?Isthesourcecodeavailable?DoyouofferanyworkshopsorothertrainingopportunitiesforNetLogo?ArethereanyNetLogotextbooks?IsNetLogoavailableinotherlanguagesbesidesEnglish?IsNetLogocompiledorinterpreted?Hasanyonebuiltamodelof<x>?AreNetLogomodelsrunsscientificallyreproducible?WillNetLogoandNetLogo3Dremainseparate?CanIrunNetLogoonmyphoneortablet?

DownloadingCanIhavemultipleversionsofNetLogoinstalledatthesametime?I'monaUNIXsystemandIcan'tuntarthedownload.Why?HowdoIinstallNetLogounattended

RunningCanIrunNetLogofromaCD,anetworkdrive,oraUSBdrive?WhyisNetLogosomuchslowerwhenIunplugmyWindowslaptop?WhydoesNetLogobundleJava?HowcomeNetLogowon'tstartuponmyLinuxmachine?WhenItrytoinstallNetLogoonWindows,Isee"WindowsprotectedyourPC"WhenItrytostartNetLogoonWindowsIgetanerror"TheJVMcouldnotbestarted".Help!NetLogowon'tstartonMacOSSierra(orlater)NetLogowon'tstartonWindowsorcrashessuddenlyonMacOSSierraCanIrunNetLogofromthecommandline,withouttheGUI?DoesNetLogotakeadvantageofmultipleprocessors?

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CanIdistributeNetLogomodelrunsacrossaclusterorgridofcomputers?IsthereanywaytorecoverlostworkifNetLogocrashesorfreezes?

UsageWhenImovethespeedsliderallthewaytotheright,whydoesmymodelseemtostop?CanIusethemouseto"paint"intheview?Howbigcanmymodelbe?Howmanyturtles,patches,procedures,buttons,andsooncanmymodelcontain?CanIuseGISdatainNetLogo?Mymodelrunsslowly.HowcanIspeeditup?CanIhavemorethanonemodelopenatatime?CanIchangethechoicesinachooseronthefly?CanIdividethecodeformymodelupintoseveralfiles?

ProgrammingHowdoestheNetLogolanguagedifferfromotherLogos?HowcomemymodelfromanearlierNetLogodoesn'tworkright?HowdoItakethenegativeofanumber?Myturtlemovedforward1,butit'sstillonthesamepatch.Why?HowdoIkeepmyturtlesonpatchcenters?patch-ahead1isreportingthesamepatchmyturtleisalreadystandingon.Why?HowdoIgivemyturtles"vision"?Canagentssensewhat'sinthedrawinglayer?I'mgettingnumberslike0.10000000004and0.799999999999insteadof0.1and0.8.Why?Thedocumentationsaysthatrandom-float1mightreturn0butwillneverreturn1.WhatifIwant1tobeincluded?HowcanIkeeptwoturtlesfromoccupyingthesamepatch?HowcanIfindoutifaturtleisdead?DoesNetLogohavearrays?DoesNetLogohavehashtablesorassociativearrays?HowcanIusedifferentpatch"neighborhoods"(circular,VonNeumann,Moore,etc.)?HowcanIconvertanagentsettoalistofagents,orviceversa?HowdoIstopforeach?I'mtryingtomakealist.WhydoIkeepgettingtheerror"Expectedaconstant"?

BehaviorSpaceWhyaretherowsinmyBehaviorSpacetableresultsoutoforder?HowdoImeasurerunseverynticks?I'mvaryingaglobalvariableIdeclaredintheCodetab,butitdoesn'twork.Why?

NetLogo3DDoesNetLogoworkwithmystereoscopicdevice?

ExtensionsI'mwritinganextension.Whydoesthecompilersayitcan'tfindorg.nlogo.api?

NetLogoDictionaryCategories

Turtle-relatedPatch-relatedLink-relatedAgentsetColorControlflowandlogicAnonymousProceduresWorldPerspectiveHubNetInput/outputFileListStringMathematicalPlottingBehaviorSpaceSystem

Built-InVariablesTurtlesPatchesLinks

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OtherKeywordsConstants

MathematicalConstantsBooleanConstantsColorConstants

Aabs1.0acos1.3all?4.0and1.0any?2.0approximate-hsb4.0approximate-rgb4.0ArithmeticOperators+1.0*1.0-1.0/1.0^1.0<1.0>1.0=1.0!=1.0<=1.0>=1.0asin1.3ask1.0ask-concurrent4.0at-points1.0atan1.0autoplot?1.0auto-plot-off1.0auto-plot-on1.0

Bback1.0bk1.0base-colors4.0beep2.1behaviorspace-experiment-name5.2behaviorspace-run-number4.1.1both-ends4.0breedbreedbut-first1.0butfirst1.0bf1.0but-last1.0butlast1.0bl1.0

Ccan-move?3.1carefully2.1ceiling1.0clear-all1.0ca1.0clear-all-plots1.0clear-drawing3.0cd3.0clear-globals5.2clear-links4.0clear-output1.0clear-patches1.0cp1.0clear-plotclear-ticks5.0clear-turtles1.0ct1.0colorcos1.0count1.0create-ordered-turtles4.0cro4.0create-<breed>-tocreate-<breeds>-tocreate-<breed>-fromcreate-<breeds>-fromcreate-<breed>-withcreate-<breeds>-withcreate-link-to4.0create-links-to4.0create-link-from4.0create-links-from4.0create-link-with4.0create-links-with4.0create-turtles1.0crt1.0create-temporary-plot-pen1.1

Ddate-and-time3.0die1.0diffuse1.0diffuse41.0directed-link-breeddisplay1.0

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distance1.0distancexy1.0downhill1.0downhill41.0dx1.0dy1.0

Eempty?1.0endend14.0end24.0error5.0error-message2.1every1.0exp1.0export-view3.0export-interface2.0export-output1.0export-plot1.0export-all-plots1.2.1export-world1.0extensionsextract-hsb1.0extract-rgb1.0

Fface3.0facexy3.0file-at-end?2.0file-close2.0file-close-all2.0file-delete2.0file-exists?2.0file-flush4.0file-open2.0file-print2.0file-read2.0file-read-characters2.0file-read-line2.0file-show2.0file-type2.0file-write2.0filter1.3first1.0floor1.0follow3.0follow-me3.0foreach1.3forward1.0fd1.0fput1.0

Gglobals

Hhatch1.0headinghidden?hide-link4.0hide-turtle1.0ht1.0histogram1.0home1.0hsb1.0hubnet-broadcast1.1hubnet-broadcast-clear-output4.1hubnet-broadcast-message4.1hubnet-clear-override4.1hubnet-clear-overrides4.1hubnet-clients-list5.0hubnet-enter-message?1.2.1hubnet-exit-message?1.2.1hubnet-fetch-message1.1hubnet-kick-client5.0hubnet-kick-all-clients5.0

392393393393393393393393393394394394394394394394395395395395395396396396396396397397397

397398398398398398398398399399399399400400400400400401401401401401401402402402402402402402403403

hubnet-message1.1hubnet-message-source1.1hubnet-message-tag1.1hubnet-message-waiting?1.1hubnet-reset1.1hubnet-reset-perspective4.1hubnet-send1.1hubnet-send-clear-output4.1hubnet-send-follow4.1hubnet-send-message4.1hubnet-send-override4.1hubnet-send-watch4.1

Iif1.0ifelse1.0ifelse-value2.0import-drawing3.0import-pcolors3.0import-pcolors-rgb4.0import-world1.0in-cone3.0in-<breed>-neighbor?in-link-neighbor?4.0in-<breed>-neighborsin-link-neighbors4.0in-<breed>-fromin-link-from4.0__includes4.0in-radius1.0insert-item6.0.2inspect1.1int1.0is-agent?1.2.1is-agentset?1.2.1is-anonymous-command?6.0is-anonymous-reporter?6.0is-boolean?1.2.1is-directed-link?4.0is-link?4.0is-link-set?4.0is-list?1.0is-number?1.2.1is-patch?1.2.1is-patch-set?4.0is-string?1.0is-turtle?1.2.1is-turtle-set?4.0is-undirected-link?4.0item1.0

Jjump1.0

Llabellabel-colorlast1.0layout-circle4.0layout-radial4.0layout-spring4.0layout-tutte4.0left1.0lt1.0length1.0let2.1link4.0link-heading4.0link-length4.0link-set4.0link-shapes4.0links4.0links-ownlist1.0ln1.0log1.0loop1.0lput1.0

Mmap1.3max1.0max-n-of4.0max-one-of1.0

403403403404404404404404405405405405405405406406406406407407407407407408408408408408408409409409409409409409410410410410410411411411411411411412412412412412413413413413413413413413414414414

max-pxcor3.1max-pycor3.1mean1.0median1.0member?1.0min1.0min-n-of4.0min-one-of1.0min-pxcor3.1min-pycor3.1mod1.0modes2.0mouse-down?1.0mouse-inside?3.0mouse-xcor1.0mouse-ycor1.0move-to4.0my-<breeds>my-links4.0my-in-<breeds>my-in-links4.0my-out-<breeds>my-out-links4.0myself1.0

Nn-of3.1n-values2.0neighbors1.1neighbors41.1<breed>-neighborslink-neighbors4.0<breed>-neighbor?link-neighbor?4.0netlogo-version3.0netlogo-web?5.2new-seed3.0no-display1.0nobodyno-links4.0no-patches4.0not1.0no-turtles4.0

Oof4.0one-of1.0or1.0other4.0other-end4.0out-<breed>-neighbor?out-link-neighbor?4.0out-<breed>-neighborsout-link-neighbors4.0out-<breed>-toout-link-to4.0output-print2.1output-show2.1output-type2.1output-write2.1

Ppatch1.0patch-ahead2.0patch-at1.0patch-at-heading-and-distance2.0patch-here1.0patch-left-and-ahead2.0patch-right-and-ahead2.0patch-set4.0patch-size4.1patches1.0patches-ownpcolorpen-down1.0pd1.0pen-erase3.0pe3.0pen-up1.0pu1.0pen-modepen-sizeplabelplabel-colorplot1.0plot-name1.0plot-pen-exists?4.0

414414414414414415415415415415415416416416416417417417418418418418418418419419419419419419419420420420420420421421421421421421422422422422422423423423423423423423423424424424424424425425425

plot-pen-down1.0plot-pen-up1.0plot-pen-reset1.0plotxy1.0plot-x-min1.0plot-x-max1.0plot-y-min1.0plot-y-max1.0position1.0precision1.0print1.0pxcorpycor

Rrandom1.0random-float2.0random-exponential1.2.1random-gamma2.0random-normal1.2.1random-poisson1.2.1random-pxcor3.1random-pycor3.1random-seed1.0random-xcor3.1random-ycor3.1range6.0read-from-string1.1reduce1.3remainder1.2.1remove1.0remove-duplicates1.0remove-item2.0repeat1.0replace-item1.0report1.0reset-perspective3.0rp3.0reset-ticks4.0reset-timer1.0resize-world4.1reverse1.0rgb1.0ride3.0ride-me3.0right1.0rt1.0round1.0run1.3runresult1.3

Sscale-color1.0self1.3;(semicolon)sentence1.0se1.0set1.0set-current-directory2.0set-current-plot1.0set-current-plot-pen1.0set-default-shape1.0set-histogram-num-bars1.0__set-line-thicknessset-patch-size4.1set-plot-background-color6.0.2set-plot-pen-color1.0set-plot-pen-interval1.0set-plot-pen-mode1.0setup-plots5.0set-plot-x-range1.0set-plot-y-range1.0setxy1.0shade-of?1.0shapeshapes2.1show1.0show-turtle1.0st1.0show-link4.0shuffle2.0

425425425426426426426427427427427427427427428428428428428428428428429429429429429430430430430430431431431431431432432432432432432433433433433433434434434434434434434435435435435435436436436

sin1.0sizesort1.0sort-by1.3sort-on5.0sprout1.0sqrt1.0stamp1.0stamp-erase3.1standard-deviation1.0startupstop1.0stop-inspecting5.2stop-inspecting-dead-agents5.2subject3.0sublist2.1substring1.0subtract-headings2.1sum1.0

Ttan1.0thicknesstick4.0tick-advance4.0ticks4.0tie4.0tie-modetimer1.0toto-reporttowards1.0towardsxy1.0turtle1.0turtle-set4.0turtles1.0turtles-at1.0turtles-here1.0turtles-on2.0turtles-owntype1.0

Uundirected-link-breeduntie4.0update-plots5.0uphill1.0uphill41.0user-directory3.1user-file3.1user-new-file3.1user-input1.1user-message1.1user-one-of3.1user-yes-or-no?2.0

Vvariance1.0

Wwait1.0watch3.0watch-me3.0while1.0whowith1.0<breed>-withlink-with4.0with-max2.1with-min2.1

436436437437437437437437438438438438438

with-local-randomness4.0without-interruption1.1word1.0world-width3.1world-height3.1wrap-color1.0write2.0

Xxcorxor1.0

Yycor

->->6.0

WhatisNetLogo?

NetLogoisaprogrammablemodelingenvironmentforsimulatingnaturalandsocialphenomena.ItwasauthoredbyUriWilenskyin1999andhasbeenincontinuousdevelopmenteversinceattheCenterforConnectedLearningandComputer-BasedModeling.

NetLogoisparticularlywellsuitedformodelingcomplexsystemsdevelopingovertime.Modelerscangiveinstructionstohundredsorthousandsof"agents"alloperatingindependently.Thismakesitpossibletoexploretheconnectionbetweenthemicro-levelbehaviorofindividualsandthemacro-levelpatternsthatemergefromtheirinteraction.

NetLogoletsstudentsopensimulationsand"play"withthem,exploringtheirbehaviorundervariousconditions.Itisalsoanauthoringenvironmentwhichenablesstudents,teachersandcurriculumdeveloperstocreatetheirownmodels.NetLogoissimpleenoughforstudentsandteachers,yetadvancedenoughtoserveasapowerfultoolforresearchersinmanyfields.

NetLogohasextensivedocumentationandtutorials.ItalsocomeswiththeModelsLibrary,alargecollectionofpre-writtensimulationsthatcanbeusedandmodified.Thesesimulationsaddresscontentareasinthenaturalandsocialsciencesincludingbiologyandmedicine,physicsandchemistry,mathematicsandcomputerscience,andeconomicsandsocialpsychology.Severalmodel-basedinquirycurriculausingNetLogoareavailableandmoreareunderdevelopment.

NetLogoisthenextgenerationoftheseriesofmulti-agentmodelinglanguagesincludingStarLogoandStarLogoT.NetLogorunsontheJavavirtualmachine,soitworksonallmajorplatforms(Mac,Windows,Linux,etal).Itisrunasadesktopapplication.Commandlineoperationisalsosupported.

Features

System:Free,opensourceCross-platform:runsonMac,Windows,Linux,etalInternationalcharactersetsupport

Programming:Fullyprogrammable

https://github.com/NetLogo/NetLogo

ApproachablesyntaxLanguageisLogodialectextendedtosupportagentsMobileagents(turtles)moveoveragridofstationaryagents(patches)Linkagentsconnectturtlestomakenetworks,graphs,andaggregatesLargevocabularyofbuilt-inlanguageprimitivesDoubleprecisionfloatingpointmathFirst-classfunctionvalues(akaanonymousprocedures,closures,lambda)Runsarereproduciblecross-platform

Environment:Commandcenterforon-the-flyinteractionInterfacebuilderw/buttons,sliders,switches,choosers,monitors,textboxes,notes,outputareaInfotabforannotatingyourmodelwithformattedtextandimagesHubNet:participatorysimulationsusingnetworkeddevicesAgentmonitorsforinspectingandcontrollingagentsExportandimportfunctions(exportdata,saveandrestorestateofmodel,makeamovie)BehaviorSpace,anopensourcetoolusedtocollectdatafrommultipleparallelrunsofamodelSystemDynamicsModelerNetLogo3Dformodeling3DworldsHeadlessmodeallowsdoingbatchrunsfromthecommandline

Displayandvisualization:Line,bar,andscatterplotsSpeedsliderletsyoufastforwardyourmodelorseeitinslowmotionViewyourmodelineither2Dor3DScalableandrotatablevectorshapesTurtleandpatchlabels

APIs:controllingAPIallowsembeddingNetLogoinascriptorapplicationextensionsAPIallowsaddingnewcommandsandreporterstotheNetLogolanguage;opensourceexampleextensionsareincluded

CopyrightandLicenseInformation

Howtoreference

IfyouuseorrefertoNetLogoinapublication,weaskthatyouciteit.Thecorrectcitationis:Wilensky,U.(1999).NetLogo.http://ccl.northwestern.edu/netlogo/.CenterforConnectedLearningandComputer-BasedModeling,NorthwesternUniversity,Evanston,IL.

ForHubNet,cite:Wilensky,U.&Stroup,W.,1999.HubNet.http://ccl.northwestern.edu/netlogo/hubnet.html.CenterforConnectedLearningandComputer-BasedModeling,NorthwesternUniversity.Evanston,IL.

FormodelsintheModelsLibrary,thecorrectcitationisincludedinthe"CreditsandReferences"sectionofeachmodel'sInfotab.

Acknowledgments

TheCCLgratefullyacknowledgestwodecadesofsupportforourNetLogowork.TheoriginalsupportcamefromtheNationalScienceFoundation--grantnumbersREC-9814682andREC-0126227.FurthersupporthascomefromREC-0003285,REC-0115699,DRL-0196044,CCF-ITR-0326542,DRL-REC/ROLE-0440113,SBE-0624318,EEC-0648316,IIS-0713619,DRL-RED-9552950,DRL-REC-9632612,andDRL-DRK12-1020101,IIS-1441552,CNS-1441016,CNS-1441041,CNS-1138461,IIS-1438813,IIS-1147621,DRL-REC-1343873,IIS-1438813,IIS-1441552,CNS-1441041,IIS-1546120,DRL-1546122,DRL-1614745andDRL-1640201.AdditionalsupportcamefromtheSpencerFoundation,TexasInstruments,theBradyFund,theMurphyfund,andtheNorthwesternInstituteonComplexSystems.

NetLogolicense

Copyright1999-2016byUriWilensky.

Thisprogramisfreesoftware;youcanredistributeitand/ormodifyitunderthetermsoftheGNUGeneralPublicLicenseaspublishedbytheFreeSoftwareFoundation;eitherversion2oftheLicense,or(atyouroption)anylaterversion.

Thisprogramisdistributedinthehopethatitwillbeuseful,butWITHOUTANYWARRANTY;withouteventheimpliedwarrantyofMERCHANTABILITYorFITNESSFORAPARTICULARPURPOSE.SeetheGNUGeneralPublicLicenseformoredetails.

YoushouldhavereceivedacopyoftheGNUGeneralPublicLicensealongwiththisprogram;ifnot,writetotheFreeSoftwareFoundation,Inc.,51FranklinStreet,FifthFloor,Boston,MA02110-1301,USA.

Commerciallicenses

Commerciallicensesarealsoavailable.Toinquireaboutcommerciallicenses,[email protected].

NetLogoUserManuallicense

Copyright1999-2016byUriWilensky.

http://ccl.northwestern.edu/netlogo/

http://ccl.northwestern.edu/netlogo/hubnet.html

mailto:[email protected]

TheNetLogoUserManualbyUriWilenskyislicensedunderaCreativeCommonsAttribution-ShareAlike3.0UnportedLicense.

Opensource

TheNetLogosourcecodeishostedathttps://github.com/NetLogo/NetLogo.Contributionsfrominterestedusersarewelcome.

Thirdpartylicenses

Scala

MuchofNetLogoiswrittenintheScalalanguageandusestheScalastandardlibraries.ThelicenseforScalaisasfollows:

Copyright (c) 2002 - EPFL

Copyright (c) 2011 - Lightbend, Inc.

All rights reserved.

Redistribution and use in source and binary forms, with or withoutmodification, are permitted provided that the following conditions are met:

Redistributions of source code must retain the above copyright notice,this list of conditions and the following disclaimer.Redistributions in binary form must reproduce the above copyright notice,this list of conditions and the following disclaimer in the documentationand/or other materials provided with the distribution.Neither the name of the EPFL nor the names of its contributors may beused to endorse or promote products derived from this software withoutspecific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THEIMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE AREDISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLEFOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIALDAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS ORSERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVERCAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USEOF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

MersenneTwisterFast

Forrandomnumbergeneration,NetLogousestheMersenneTwisterFastclassbySeanLuke.Thecopyrightforthatcodeisasfollows:

Copyright (c) 2003 by Sean Luke. Portions copyright (c) 1993 by Michael Lecuyer. All rights reserved.


http://creativecommons.org/licenses/by-sa/3.0/




Redistributions of source code must retain the above copyright notice,this list of conditions and the following disclaimer.Redistributions in binary form must reproduce the above copyright notice,this list of conditions and the following disclaimer in the documentationand/or other materials provided with the distribution.Neither the name of the copyright owners, their employers, nor the namesof its contributors may be used to endorse or promote products derivedfrom this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THEIMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE AREDISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNERS OR CONTRIBUTORS BE LIABLEFOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIALDAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS ORSERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVERCAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USEOF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Colt

PartsofNetLogo(specifically,therandom-gammaprimitive)arebasedoncodefromtheColtlibrary(http://acs.lbl.gov/~hoschek/colt/).Thecopyrightforthatcodeisasfollows:

Copyright 1999 CERN - European Organization for Nuclear Research. Permissionto use, copy, modify, distribute and sell this software and its documentationfor any purpose is hereby granted without fee, provided that the abovecopyright notice appear in all copies and that both that copyright notice andthis permission notice appear in supporting documentation. CERN makes norepresentations about the suitability of this software for any purpose. It isprovided "as is" without expressed or implied warranty.

Config

NetLogousestheTypesafe"Config"library.Copyright(C)2011-2012TypesafeInc.http://typesafe.comTheConfiglibraryislicensedundertheApache2.0License.Youmayobtainacopyofthelicenseathttp://www.apache.org/licenses/LICENSE-2.0.

ApacheCommonsCodec(TM)

TheNetLogocompilerusesadigestmethodfromtheApacheCommonsCodec(TM)library.ApacheCommonsCodec(TM)iscopyrightandtrademark2002-2014theApacheSoftwareFoundation.ItislicensedundertheApache2.0License.Youmayobtainacopyofthelicenseathttp://www.apache.org/licenses/LICENSE-2.0.

Flexmark

NetLogousestheFlexmarklibrary(andextensions)fortheinfotab.Thecopyrightandlicenseareasfollows:

Copyright (c) 2015-2016, Atlassian Pty Ltd All rights reserved. Copyright (c)2016, Vladimir Schneider, All rights reserved. Redistribution and use in

http://acs.lbl.gov/~hoschek/colt/

http://typesafe.com

http://www.apache.org/licenses/LICENSE-2.0


source and binary forms, with or without modification, are permitted providedthat the following conditions are met: * Redistributions of source code mustretain the above copyright notice, this list of conditions and the followingdisclaimer. * Redistributions in binary form must reproduce the abovecopyright notice, this list of conditions and the following disclaimer in thedocumentation and/or other materials provided with the distribution. THISSOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANYEXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIEDWARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE AREDISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLEFOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIALDAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS ORSERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVERCAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USEOF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

JHotDraw

Forthesystemdynamicsmodeler,NetLogousestheJHotDrawlibrary,whichisCopyright(c)1996,1997byIFAInformatikandErichGamma.ThelibraryiscoveredbytheGNULGPL(LesserGeneralPublicLicense).Thetextofthatlicenseisincludedinthe"docs"folderwhichaccompaniestheNetLogodownload,andisalsoavailablefromhttp://www.gnu.org/copyleft/lesser.html.

JOGL

For3Dgraphicsrendering,NetLogousesJOGL,aJavaAPIforOpenGL,andGluegen,anautomaticcodegenerationtool.FormoreinformationaboutJOGLandGluegen,seejogamp.org/.BothlibrariesaredistributedundertheBSDlicense:

Copyright 2010 JogAmp Community. All rights reserved.


1. Redistributions of source code must retain the above copyright notice, thislist of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice,this list of conditions and the following disclaimer in the documentationand/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY JogAmp Community ``AS IS'' AND ANY EXPRESS ORIMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OFMERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NOEVENT SHALL JogAmp Community OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORYOF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDINGNEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

The views and conclusions contained in the software and documentation arethose of the authors and should not be interpreted as representing officialpolicies, either expressed or implied, of JogAmp Community.

You can address the JogAmp Community via: Web http://jogamp.org/Forum/Mailinglist http://forum.jogamp.org Chatrooms IRC irc.freenode.net#jogamp Jabber conference.jabber.org room: jogamp (deprecated!) Repositoryhttp://jogamp.org/git/ Email mediastream _at_ jogamp _dot_ org

http://www.gnu.org/copyleft/lesser.html

http://jogamp.org/

Matrix3D

For3Dmatrixoperations,NetLogousestheMatrix3Dclass.Itisdistributedunderthefollowinglicense:

Copyright (c) 1994-1996 Sun Microsystems, Inc. All Rights Reserved.

Sun grants you ("Licensee") a non-exclusive, royalty free, license to use,modify and redistribute this software in source and binary code form, providedthat i) this copyright notice and license appear on all copies of thesoftware; and ii) Licensee does not utilize the software in a manner which isdisparaging to Sun.

This software is provided "AS IS," without a warranty of any kind. ALL EXPRESSOR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING ANY IMPLIEDWARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN AND ITS LICENSORS SHALL NOT BE LIABLEFOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING ORDISTRIBUTING THE SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR ITSLICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT,INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVERCAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF ORINABILITY TO USE SOFTWARE, EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OFSUCH DAMAGES.

This software is not designed or intended for use in on-line control ofaircraft, air traffic, aircraft navigation or aircraft communications; or inthe design, construction, operation or maintenance of any nuclear facility.Licensee represents and warrants that it will not use or redistribute theSoftware for such purposes.

ASM

ForJavabytecodegeneration,NetLogousestheASMlibrary.Itisdistributedunderthefollowinglicense:

Copyright (c) 2000-2011 INRIA, France Telecom. All rights reserved.


1. Redistributions of source code must retain the above copyright notice, thislist of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice,this list of conditions and the following disclaimer in the documentationand/or other materials provided with the distribution.

3. Neither the name of the copyright holders nor the names of its contributorsmay be used to endorse or promote products derived from this software withoutspecific prior written permission.


Log4j

Forlogging,NetLogousestheLog4jlibrary.Thecopyrightandlicenseforthelibraryareasfollows:

Copyright 2007 The Apache Software Foundation

Licensed under the Apache License, Version 2.0 (the "License"); you may notuse this file except in compliance with the License. You may obtain a copy ofthe License at


Unless required by applicable law or agreed to in writing, softwaredistributed under the License is distributed on an "AS IS" BASIS, WITHOUTWARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See theLicense for the specific language governing permissions and limitations underthe License.

PicoContainer

Fordependencyinjection,NetLogousesthePicoContainerlibrary.Thecopyrightandlicenseforthelibraryareasfollows:

Copyright (c) 2004-2011, PicoContainer Organization All rights reserved.


Redistributions of source code must retain the above copyright notice,this list of conditions and the following disclaimer.Redistributions in binary form must reproduce the above copyright notice,this list of conditions and the following disclaimer in the documentationand/or other materials provided with the distribution.Neither the name of the PicoContainer Organization nor the names of itscontributors may be used to endorse or promote products derived from thissoftware without specific prior written permission.


Parboiled

Forreadingmodels,NetLogousestheParboiledlibrary.ThecopyrightandlicenseforParboiledareasfollows:

This software is licensed under the Apache 2 license, quoted below. Copyright


© 2009-2013 Mathias Doenitz http://parboiled2.org Copyright © 2013 AlexanderMyltsev Licensed under the Apache License, Version 2.0 (the "License"); youmay not use this file except in compliance with the License. You may obtain acopy of the License at [http://www.apache.org/licenses/LICENSE-2.0] Unlessrequired by applicable law or agreed to in writing, software distributed underthe License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES ORCONDITIONS OF ANY KIND, either express or implied. See the License for thespecific language governing permissions and limitations under the License.

RSyntaxTextArea

TheNetLogoeditorusestheRSyntaxTextArealibrary.Thecopyrightandlicenseareasfollows:

Redistribution and use in source and binary forms, with or withoutmodification, are permitted provided that the following conditions are met: *Redistributions of source code must retain the above copyright notice, thislist of conditions and the following disclaimer. * Redistributions in binaryform must reproduce the above copyright notice, this list of conditions andthe following disclaimer in the documentation and/or other materials providedwith the distribution. * Neither the name of the author nor the names of itscontributors may be used to endorse or promote products derived from thissoftware without specific prior written permission. THIS SOFTWARE IS PROVIDEDBY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIEDWARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OFMERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NOEVENT SHALL &COPYRIGHT HOLDER& BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; ORBUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHERIN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THEPOSSIBILITY OF SUCH DAMAGE.

JCodec

TheNetLogovidextensionmakesuseoftheJCodeclibrary.ThecopyrightandlicenseforJCodecareasfollows:

Redistribution and use in source and binary forms, with or withoutmodification, are permitted provided that the following conditions are met:Redistributions of source code must retain the above copyright notice, thislist of conditions and the following disclaimer. Redistributions in binaryform must reproduce the above copyright notice, this list of conditions andthe following disclaimer in the documentation and/or other materials providedwith the distribution. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ANDCONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOTLIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR APARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER ORCONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; ORBUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHERIN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THEPOSSIBILITY OF SUCH DAMAGE.

Java-Objective-CBridge

http://parboiled2.org

NetLogoonMacOSXmakesuseoftheJava-Objective-CBridgelibrary.ThislibrarywascreatedbySteveHannahandisdistributedundertheApache2.0license,availableathttps://www.apache.org/licenses/LICENSE-2.0.

Webcam-capture

TheNetLogovidextensionmakesuseoftheWebcam-capturelibrary.ThecopyrightandlicenseforWebcam-captureareasfollows:

The MIT License (MIT) Copyright (c) 2012 - 2015 Bartosz Firyn and ContributorsPermission is hereby granted, free of charge, to any person obtaining a copyof this software and associated documentation files (the "Software"), to dealin the Software without restriction, including without limitation the rightsto use, copy, modify, merge, publish, distribute, sublicense, and/or sellcopies of the Software, and to permit persons to whom the Software isfurnished to do so, subject to the following conditions: The above copyrightnotice and this permission notice shall be included in all copies orsubstantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS",WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TOTHE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE ANDNONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLEFOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE ORTHE USE OR OTHER DEALINGS IN THE SOFTWARE.

Guava

TheNetLogolsextensionmakesuseoftheGuavalibrary.GuavaisreleasedundertheApacheLicense2.0(http://www.apache.org/licenses/LICENSE-2.0)

Gephi

ThenwextensionmakesuseoftheGephilibrary.Gephiislicensedunderthefollowingterms:

Gephi Dual License Header and License Notice

The Gephi Consortium elects to use only the GNU General Public License version3 (GPL) for any software where a choice of GPL license versions are madeavailable with the language indicating that GPLv3 or any later version may beused, or where a choice of which version of the GPL is applied is unspecified.

For more information on the license please see: the Gephi License FAQs.

License headers are available on http://www.opensource.org/licenses/CDDL-1.0and http://www.gnu.org/licenses/gpl.html.

RExtension

TheNetLogoRExtensionislicensedunderthefollowingterms:

The R extension is Copyright (C) 2009-2016 Jan C. Thiele and Copyright (C)2016 Uri Wilensky / The Center for Connected Learning. NetLogo-R-Extension isfree software; you can redistribute it and/or modify it under the terms of theGNU General Public License as published by the Free Software Foundation;either version 2 of the License, or (at your option) any later version. This

https://www.apache.org/licenses/LICENSE-2.0


program is distributed in the hope that it will be useful, but WITHOUT ANYWARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FORA PARTICULAR PURPOSE. See the GNU General Public License for more details. Youshould have received a copy of the GNU General Public License along withNetLogo-R-Extension (located in GPL.txt). If not, seehttp://www.gnu.org/licenses.

JNA

TheNetLogoRExtensionmakesuseoftheJNAlibrary.TheJNAlibraryislicensedunderthefollowingterms:

This copy of JNA is licensed under the Apache (Software) License, version 2.0("the License"). See the License for details about distribution rights, andthe specific rights regarding derivate works. You may obtain a copy of theLicense at: http://www.apache.org/licenses/

http://www.gnu.org/licenses/

What'sNew?NetLogo6.0.2UserManual

Thefollowingisacondensedhistory.DetailedreleasenotesareonGitHub.

Forhelprunningmodelsmadeinoldversions,seetheTransitionGuide.

Version6.0.2(August2017)

FeatureChanges

TheautosuggestfunctionalityintroducedinNetLogo6willnowdisplayextensionprimitivenames.Anewinsert-itemprimitivewasaddedtothelanguage.Itworkssimilarlytoreplace-item,butwithoutremovingtheitematthespecifiedindex.Anewset-plot-background-colorprimitivewasaddedtothelanguage.Itcanbeusedinplottingcodetosetthebackgroundcoloroftheplot.Behaviorsearch'suserinterfacehasbeenupdated.ItnowusestheJavaFXUItoolkitforamoremodernlookandfeel.

Bugfixes

The6.0.1autoconverterwoulderrorwhenconvertingtaskswithexactlyoneargument(from5.3.1andearliermodelsonly).Theconversionwouldbecorrect,butitwasconfusing.Thishasnowbeenremediedandtheautoconverterwillcorrectlyconvertmodelsfrom5.3.1andearlierwithouterroringonsingle-argumenttasks.Fixabugwhereextensionsweren'tlocatedproperlywheninapathrelativetothemodel.Helpbrowsernowopensin64-bitWindows.Fixaspeedregressionfortheimport-worldprimitiveintroducedin6.0.Ifanunexpectedreporterblockispassedtowithwhenusedwithother,theerrorwillnowreflectthattheblockisunsuitableforwithinsteadofother.Whensort-byreceivesanunsuitablereporterblockfromtheuseritnowshowsausefulerrorinsteadofacrypticstacktrace.StringrepresentationsofanonymousproceduresnowshowtheargumentsofthoseanonymousproceduresWhenworkinginannlsfile,switchingtoadifferenttabwillcompilethenlsfile.Displayerrorlabelonnlsfilewhenthecodeitcontainscausesanerror.SomeuserswereunabletoopenNetLogo6and6.0.1inMacOSSierra.We'vechangedoursigningprocessin6.0.2toattempttofixthisproblem.Wearecontinuingtotrackthisissuetodeterminewhetherourfixwaseffective.Moreinformation(includingapartialworkaroundfortheproblem)isavailablehere.

ExtensionChanges

Fixedabugingis:patch-datasetintroducedinNetLogo6.Thetableextensionhasnewtable:group-agentsandtable:group-itemsprimitiveswhichcanbeusedtobuildatableofgroupedagentsanditemsbysupplyingananonymousreporter.

DocumentationChanges

https://github.com/NetLogo/NetLogo/wiki/Release-notes

https://github.com/NetLogo/NetLogo/wiki/Known-Issues#netlogo-wont-start-on-mac-os-sierra

Clarifywhenvariouspartsoftheanonymousproceduresyntaxareoptional.Fixafewsmalldocumentationbugsaroundforeach.Clarifyrelationshipbetweenspeedandupdatemodalityinthe"ViewUpdates"sectionoftheprogrammingguide.

ModelChanges

NewSampleModels:

ChaosinaBoxFairyCirclesSmoothLife

NewCurricularModels:

LatticeLandCurriculumLatticeLand-TrianglesExploreLatticeLand-TrianglesDissection

RevisedSampleModels:

Anisogamy:Newcolorscheme.AddsBehaviorSpaceexperiments.Ethnocentrism:Nowcross-listedasanEvolutionarymodel.Fireworks:Renamefireworkstomax-fireworksandenforceaminimumof1.GenJam-Duple:Minorinfotabupdates.WolfSheepPredation:Revisedtobetterclarifythegrass?constructandcode.

RevisedCurricularModels:

ConnectedChemistry:ConnectedChemistry1:FixNetLogoWebincompatibility.ConnectedChemistry3:Updateminimumnumberofparticlesto2.ConnectedChemistry8:Minorcodeupdates.Smallchangetodefaultvalues.

RevisedHubNetActivities:

GridlockHubNet:Minorcodeupdates.

RevisedCodeExamples:

InfoTabExample:Correctedformattingofun/orderedlistsexample.LSExtension–ModelVisualizerandPlotterExample:UpdatedcodedependenciesforWSP.LSExtension–ModelInteractionsExample:UpdatedcodedependenciesforWSP.

Version6.0.1(March2017)

FeatureChanges

Bracketsarerequiredaroundanonymousprocedurereportersonlywhentherearetwoormorearguments.Forinstance[ [x] -> x ] cannowbewritten[ x -> x ] .NotethischangemakesitpossibletocreatemodelsinNetLogo6.0.1thatwillnotruninNetLogo6.0.IfyouplantouseyourmodelinNetLogo6.0,besuretoincludebracketsaroundanonymousprocedurearguments.Forashortperiodaftertherelease,modelswhichuseunbracketedlambdaargumentsmaynotworkonnetlogoweb.org.

Bugfixes

TheNetLogocodeeditornavigatesandindentsmodelsmuchmorequicklyandefficientlythaninNetLogo6.0.TheNetLogo5-to-6autoconverternowignorescommented-outcode.Thebehavioroflayout-radialinNetLogo6didnotmatchthe5.3.1behavior.Thishasbeencorrectedandlayout-radialshouldbeidenticalbetweenNetLogo6.0.1andNetLogo5.3.1NetLogo6raisedaNullPointerExceptionwhennumbersbecametoolargeforNetLogotohandle.Thisisnowproperlydisplayedtotheuserasanumberoutofboundserror.Improvedperformanceofmodelswhichuseletandanonymousprocedurestogether.Reloadingamodelnowclearsglobalvariables.ClearerwarningdialogswhenopeninganolderversionofaNetLogo2DfileinNetLogo3D.UsingforeachimproperlyintheCommandCenterwilldisplaythesameerrorasitwouldifusedimproperlyinthecodetab.Extremelylonganonymousproceduresnolongercauseanexceptionwhencompiled.in-radiusisnolongerpathologicallyslowonagentsetscreatedusingwith.

ExtensionChanges

Anewprimitive,table:valueshasbeenaddedtothetableextension.TheRextensionhasbeenupdatedtotakefulladvantageoftheJavaGDRlibraryusingr:setPlotDevice.UserscannowsupplyapathtotheRextensionbyconfiguringthevalueofr.lib.pathsintheuser.propertiesfile.FixedaLevelSpacebugpreventinginteractivemodelsfromusingnlsfiles.FixedaLevelSpacebugcausingNetLogotolockupwhentryingtoloadanonexistentfileasaninteractivemodel.


ThesystemdynamicstutorialnowinstructstheusertosetthedttoavaluewhichgivesstablebehaviorThedocumentationforfollow,ride,andwatchhasbeenclarifiedtoindicatethatcallingoneundoeshighlightsandperspectivechangescausedbytheotherThedocumentationfor=and!=indicatesthattheyworkwithextensionobjects.Severalexampleshavebeenaddedtosortclarifyingthebehaviorofsortonlistsfeaturingdifferenttypesofobjects.AnewsectiononUserInterfaceprimitiveshasbeenaddedtotheprogrammingguidewhichdiscussesthebehaviorofthe"Halt"buttoninthevarioususerinteractiondialogs.Incorrectexamplecodeforforeachandreducehasbeencorrected.

Models

Allmodelshavebeenupdatedtoreflectthenewoptionalnatureofbracketsforzero/one

argumentanonymousprocedures.Thisresultedinchangesto108models.

Allmodelshavebeenupdatedtoreflecttheavailabilityofthenewrangeprimitive.Thisresultedinchangesto12models.

NewSampleModel

GenJam-Duple

NewCurricularModel

LatticeLandcurriculum:LatticeLandExplore

RevisedSampleModels

PD2PersonIterated:infotabupdatesandextensivefixesforthecode.Party:fixedbugwhereamonitorcoveredaplot.SignalingGame:infotabupdates.

RevisedCurricularModels

GenEvocurriculum:GenEvo1GeneticSwitch:infotabupdatesandnewgraduatedmethodofdisplayinglacZconcentration.GenEvo2GeneticDrift:infotabupdatesandinterfacetweaks.Newmodelpreview.GenEvo3GeneticDriftandNaturalSelection:infotabupdatesandinterfacetweaks.GenEvo4Competition:infotabupdates.GeneticSwitch-SyntheticBiologyhasbeenrenamedandisnowSyntheticBiology-GeneticSwitch.Italsoreceivedinfotabupdatesandafewinterfacechanges.

Version6.0(December2016)

FeatureChanges

TheNetLogocodeeditornowoffersautocompletionsupport.SimplypresstheControlkeyandthespacebaratthesametimewhiletypingawordandyouwillseealistofsimilarNetLogoprimitivesassuggestions.TheNetLogocodeeditorofferstheoptionto"fold"procedurestomakenavigatinglargemodelssimpler.NetLogosupportsmulti-levelagent-basedmodelingwiththeLevelSpaceextensionLinenumberingcanbeenabledintheNetLogocodeeditorbychoosing"ShowLineNumbers"fromthe"Preferences"dialog.Thisdialogcanbeopenedbyselecting"NetLogo">"Preferences"inMac,or"Tools">"Preferences"onLinuxorWindows.Theviewresizingarrowshavebeenremovedandthetickcounterhasbeenrelocatedunderthespeedslider.WheneditingNetLogocode,userscanright-clickavariablenameorprimitiveandchoose"ShowUsage"toseeallusagesofthatnameinthefile.

WheneditingNetLogocode,userscanright-clickavariablenameandchoose"JumptoDeclaration"toseewhereinthefilethatvariableisdeclared.TheNetLogointerfaceeditornowsupports"Undo"forwidgetaddition,deletion,andmovement.NetLogocanexportcodetoHTMLwithcode-colorizationbychoosing"ExportCode"inthe"Export"sectionofthe"File"menu.ThelookandfeelofNetLogoonMacOSXhaschangedsignificantly.NetLogoisnowusingtheOracle-suppliedJavalookandfeelasopposedtoathird-partylookandfeelusedinpriorversions.Plotsusearandomnumbergeneratorindependentofthemain-modelrandomnumbergenerator.ModelPreviewCommandscanbeeditedthroughtheGUIbychoosing"PreviewCommandsEditor"inthe"Tools"menu.ThosecommandsgeneratethepreviewimagethatappearswhenyouuploadyourmodeltotheModelingCommons.NetLogodisplaysamorehelpfulerrormessagewhenaprogramfailsduetoan"outofmemory"error.NetLogoanditsbundledextensionsarenowcompiledagainstJava8andScala2.12.NetLogohasupgradedtheASMbytecodelibrarytoenablegenerationofJava8bytecode.

Bugfixes

*-link-neighbor?primitivesnowworkthesamewayforbreededandunbreededlinks.ResizingtheworldinNetLogo3Dnolongercausesablackview.Fixederrorcausedbyright-clickingawidgetwhiledragging.Improvederrormessagewhenauser-definedprocedureshadowsabreedprocedure.neighbors4andneighborsnolongerreportagentsetscontainingthesamepatchmorethanonce.

LanguageChanges

Supportforplural-onlybreednames(e.g.,breed [mice])hasbeenremoved.Writebreed[mice mouse]instead.Taskshavebeenreplacedbyanonymousprocedures.Tasksmadeuseof?variableswhichwereconfusingfornovicesanddifficulttoreadforexperts.Additionally,taskscouldnotrefertothetaskvariablesofacontainingtask.Anonymousproceduresmayhavenamedargumentswhichcanbeaccessedbyinneranonymoustasks.UponfirstopeningaNetLogo5modelinNetLogo6,tasksliketask [ ?1 + ?2 ] willbeautomaticallyconvertedto[ [?1 ?2] -> ?1 + ?2 ] .Seethethetransitionguideformoreinformation.LinkreportershavebeenoverhauledtobemoreconsistentandflexibleThetaskprimitiveisnolongersupported.Breednamesthatconflictwithlanguageprimitivesarenowdisallowed.Forinstance,breed [strings string]isnowdisallowedsinceitmakesis-string?ambiguous.Thecompilererrorsonduplicatedbreedsingularnames.Thecompilerdetectsagreaternumberoftypeerrors,forinstancenot pxcornowraisesacompilererrorinsteadoferroringatruntime.set-plot-pen-colornowacceptsRGBlistsasarguments.Thehubnet-set-client-interfaceprimitivehasbeenremoved.Thevariousprimitivesstartingwithmovie-havebeenremoved,ashasthemovieencoder.Theyhavebeenreplacedwiththenewvidextension.Thetransitionguideprovidesmoredetailsandinformation.The__change-languageprimitivehasbeenremoved.YoucannowchangetheUserInterfaceLanguagethroughthepreferencesdialog,whichcanbefoundbychoosing

"Preferences..."inthe"NetLogo"menu(MacOSX)orinthe"Tools"menu(allotherplatforms).Thestringrepresentationofanonymousproceduresdisplaysthebodyoftheanonymousprocedure.

ExtensionChanges

NetLogo6.0comeswiththreenew,bundledextensions:LevelSpacels,thevidextensionforvideomanipulation,andtheenhancedvisualizationextensionview2.5d.lsenablesmulti-levelagent-basedmodelinginNetLogo.TheExtensionsAPIhasbeenupdatedfrom5.0to6.0.Thismeansthatallnon-bundledextensionswillneedtobeupdatedtousethenewAPI.ExtensionswrittenforNetLogo5willnotworkinNetLogo6.Ifyou'reanextensionauthor,seetheextensionauthortransitionguidefor6.0formoreinformation.IfyouregularlyuseextensionsyoumaywanttocontacttheirauthorstoinformthemanewversionofNetLogoisonthewayandtheymaywanttoupdatetheirextensions.arduino:get(inthearduinoextension)correctlyreportsvaluesfromWindows64-bitmachines.Inpriorversionsitwouldonlyreportsomevaluescorrectly.Severalnewfeatureshavebeenaddedtothenwextension:

AddedcommunitydetectionusingtheLouvainmethodAddedmodularitymeasurementAddedWatts-Strogatzsmall-worldnetworkgenerationMadeothernetworkgenerationalgorithmseasiertolayoutWeightedprimitivesnowtakesymbolicvariablenamesinsteadofstrings.Seethetransitionguideformoreinformation.

TheqtjextensionisnolongerbundledwithNetLogo.Usersareencouragedtomakeuseofthenewvidextension.ThenewvidextensionisnowbundledwithNetLogo,combiningfeaturesofthelateqtjextensionandthemovieprimitives.ThenetworkextensionisnolongerbundledwithNetLogo.Usersareencouragedtousethenwextension(https://ccl.northwestern.edu/netlogo/docs/nw.html),whichhasbeenbundledwithNetLogoforsometime.Thegogo-serialextensionisnolongerbundledwithNetLogo.Usersareencouragedtotransitiontothenewergogoextension,whichusesHIDtocommunicatewiththeGoGoboard.

OperatingSystemSupport

NetLogowillnowbeusedtoopen.nlogolinksinPowerPointandotherprogramsonMicrosoftWindows.TheNetLogobinariesonMacOSXareinstalledasrunnablebyanyuser.NetLogoinMacOSXwillnotuse"AppNap"whilerunning.ThiskeepssimulationsrunningatfullspeedwhenNetLogoisinthebackground.TheNetLogocontrollingAPIhaschangedsinceNetLogo5.ProgramsthatrelyonthecontrollingAPI(suchasBehaviorSearch)willnotworkuntiltheyhavebeenchangedtomatchthenewAPI.


NewdocumentationforanonymousproceduresTheNetLogotutorialscreenshotshavebeenupdatedtocorrespondtothenewMacOSXLookandFeel.TheNetLogodictionarydisplaystheversioninwhicheachprimitivewasintroducednexttothatprimitive.

https://github.com/NetLogo/NetLogo/wiki/Hexy-Extension-Transition-Guide

ASpanishtranslationoftheNetLogodictionaryisavailablehere

InternationalizationChanges

AnewSpanishtranslationoftheNetLogodictionaryisavailableaspartoftheNetLogomanual.Languagepreferencescanbechangedbyusingthenew"Preferences"menuinsteadofthe__change-languageprimitive.AJapaneselocalizationforNetLogoisnowavailableandincludedwiththestandarddownload.TheChinesetranslationforNetLogohasbeenupdated.

Models

NewSampleModels:

KickedRotatorKickedRotatorsMammoths,alegacyStarLogoTmodel,hasbeenconvertedtoNetLogo.

NewCurricularModels:

GenEvo1GeneticSwitchGenEvo2GeneticDriftGenEvo3GeneticDriftandNaturalSelectionGenEvo4Competition

NewCodeExamples:

MoviePlayingExample(vidextension)MovieRecordingExample(vidextension)VideoCameraExample(vidextension)NetworkExtensionGeneralDemo(nwextension)ModelInteractionsExample(lsextension)ModelLoaderExample(lsextension)ModelVisualizerandPlotterExample(lsextension)

PromotedModels(improvedandnolonger"unverified"):

ProbLabGeneticsTraffic2Lanes

RevisedSampleModels:

GiantComponent:addedtextintheinfotab.TeamAssembly:removedunusedswitchwidget.TrafficBasic,TrafficGrid,TrafficIntersection:revisedinfotab.Voting:stoppedthemodelwhenvotingstabilizes.WealthDistribution:fixedtyposininfotab,improvedcodeformatting.

diccionario.pdf

diccionario.pdf

RevisedHubNetActivities:

BugHuntersCompetitionHubNet,CritterDesignersHubNet,FishSpottersHubNet:removedunnecessarycalltohubnet-set-client-interface.GridlockHubNet,GridlockAlternateHubNet:revisedinfotab.

RevisedCurricularModels:

DNAReplicationFork:fixedaamonitorandruntimeerrorwhenusingatimelimit.

RevisedIABMmodels:

AgentsetEfficiency:clarifieddescriptionofgo-2ininfotab.AgentsetOrdering:fixedtyposinintotab.ArduinoExample:improvedmodeltodemonstratebothdirectionsofcommunicationwiththeArduino.HeroesandCowards:removedextratextininfotab.PreferentialAttachmentSimple:removedextrapeninplotandextra"layout"button.RandomNetwork:madesurethatthenumberoflinksisnevertoobigforthenumberofnodes.SegregationSimpleExtension1,2and3:fixednumber-of-ethnicitiesslidertoavoidruntimeerrors.TrafficBasicAdaptiveIndividuals,TrafficBasicUtility,TrafficGridGoal:revisedinfotab.TrafficBasicAdaptive:revisedinfotab,clarifiedcommentinadaptive-goprocedure.VotingComponentVerification:stoppedthemodelwhenvotingstabilizes.VotingSensitivityAnalysis:improvedcodeforstoppingthemodelwhenvotingstabilizes.

RevisedCodeExamples:

GoGoMonitorSerial,GoGoMonitorSimpleSerial:removedthemodels,asthegogo-serialandqtjextensionsarenolongerbundled.RandomNetworkExample:madesurethatthenumberoflinksisnevertoobigforthenumberofnodes.SincetheQuickTimeextension(qtj)hasbeenreplacedbythevidextension,thefollowingmodelshavebeenconvertedtousethevidextension:

MovieExample,replacedbyMovieRecordingExampleQuickTimeMovieExample,replacedbyMoviePlayingExampleQuickTimeCameraExample,replacedbyVideoCameraExample

Demotedmodel:

ElFarolNetworkCongestion,apreviously"unverified"model,hasbeenmovedtotheNetLogoUserCommunityModels

Version5.3.1(February2016)

FeatureChanges

MathematicaLinkisnowincludedandhasbeentestedtoworkwithMathematica10.

AlinktoIntroductiontoAgent-BasedModellinghasbeenaddedtothe"Help"menu.

ExtensionChanges

ThegogoextensionnowpromptstheuserforthelocationofJavauponopening.ThisversionofJavaisusedtolaunchthegogohiddaemon.Thecorrectversionofthenetworkextensionisnowbundled,whichwillopenproperlyBundlesthecfextension,whichaddsmatch,case,andselectprimitives.

Bugfixes

Correctsabugwhereturtleswrappingaroundatorus-shapedworldwithpendownwouldsometimescauseNetLogotoloopinfinitely.FixesabugwherebuttonswouldappeartoremainpressedafterarightclickonMac.Fixesabugwherepressingtherightmousebuttonwhiledraggingwouldconfusethemouse-down?primitive.Fixesagenttype-checkingoftasks(bugappearedin5.2.1).link-neighbor?nowreturnstrueifandonlyiftheneighborisconnectedthroughanundirectedlink.Documentationfixesformy-linksandmeanprimitives.


FeatureChanges

Java8isnowbundledwithallversionsofNetLogo,thisremovestheneedforaseparateJava6installationonMacOSXSeparate32-bitand64-bitversionsareavailableforbothWindowsandLinuxTheWindowsinstallerisnowanmsiinsteadofanexejavax.media.openglisnolongersupportedinJava8,ithasbeenreplacedbycom.jogamp.openglMathematicaLinkisnotdistributedduetoJavaversionchanges

ExtensionChanges

Aminorupdatetothenwextensionmakesnw:weighted-path-tobehaveasdocumented.Mostextensionsshouldcontinuetoworkwithoutchangeunlesstheyrelyonjavax.media.opengl,whichwasrenamedintheupdatedversionofJOGL.

Version5.2.1(September2015)

Extensions

AnincludedArduinoextensionforusewithArduinoboards

Newfeatures

NewfilemenuitemtoexportmodelstoNetLogoWeb

Bugfixes

BehaviorSpaceoutputtypepreferenceisnowrememberedOutputwidgetfontisnowsavedatthepropersizewhenzoomedReportertasksarenowevaluatedinvariablecontextrunresultargumentsnowonlygetevaluatedonceThelastuseddirectoryisnowrememberedonLinuxWhitespaceisnowstrippedfrommodelswhensaving

NewSampleModels:ArtificialAnasazi,BacteriaFoodHunt,BacteriaHuntSpeeds,BeeSmart-HiveFinding,BugHuntDisruptions,BugHuntEnvironmentalChanges,BugHuntPredatorsandInvasiveSpecies-TwoRegions,HydrogenDiffusion3D,Lennard-Jones,PathsThereare46newmodelsinthenewIABMTextbookfolder:TurtlesCirclingSimple,AntsSimple,HeroesandCowards,LifeSimple,SimpleEconomy,4DLAextensions,4ElFarolExtensions,4FireExtensions,4SegregationExtensions,5WolfSheepExtensions,AgentsetEfficiency,AgentsetOrdering,Communication-T-TNetworkExample,PreferentialAttachmentSimple,RandomNetwork,TrafficBasicAdaptive,TrafficBasicUtility,TrafficGridGoal,SpreadofDisease,VotingComponentVerification,VotingSensitivityAnalysis,ArduinoExample,DiseaseWithAndroidAvoidanceHubNet,ExampleHubNet,RunExample,RunResultExample,SimpleMachineLearning,SimpleViralMarketing,TicketSales,SandpileSimpleNewmodelsinthenewAlternateVisualizationsfolder:Ethnocentrism-AlternativeVisualization,Flocking-AlternativeVisualizations,HeatDiffusion-Alternativevisualization,Virus-AlternativeVisualization,Virus-CircleVisualizationPromotedmodels:Honeycomb,MinorityGameManyotherbugfixesandupgrades

Modelchanges

ImprovedSampleModels:Altruism,AntLines,ArtificialAnasazi,Cooperation,Daisyworld,DividetheCake,HeatDiffusion,HydrogenDiffusion3D,Lennard-Jones,N-Bodies,PDBasicEvolutionary,Sandpile,RobbytheRobot,Segregation,SimpleKinetics2and3,TrafficGrid,GridLockHubNet,GridLockHubNetAlternateRevisedCurricularModels:4BlockStalagmites,4BlockTwoStalagmites,BugHunterCompetitionHubNet,FishSpottersHubNet,Ising,TijuanaBordertowns,UrbanSuite-TijuanaBordertowns,RevisedCodeExamples:LotteryExample,selfExample,NetworkImportExampleRevisedIABMTextbookmodels:SimpleEconomy,FireSimpleExtension2and3,SegregationSimple,1,2and3,AgentsetEfficiency,PreferentialAttachmentSimple,RandomNetwork,TrafficBasicAdaptive,RunExample,TrafficGridGoal,NewIABMTextbookmodel:TrafficBasicAdaptiveIndividuals

Version5.2.0(April2015)

Extensions

AnincludedCSVextensiontoreadandwriteCSVfilesAnincludedPaletteextensiontomapdifferentvaluestocolorsThepreviousgogoextensionhasbeenremoved.Ithasbeenreplacedwithtwodifferentgogoextensions,gogoandgogo-serial.Theextensionsworkwithdifferenthardware.ThegogoextensionworkswiththenewstyleHID-interfacegogoboardsandthegogo-serialextensionworkswiththeold-styleserial-interfacegogoboards

Upgradetothenetworkextensionincludingthefollowingchanges:Supportformanymorefiletypes,includingGEXF,GDF,GML,PajekNET,UCINETDL,andNetdrawVNAFixedbugswithGraphMLsupportImproveddocumentation

Newfeatures

Newprimitivenetlogo-web?addedtotestwhetheryouarecurrentlyrunninginNetLogoWebNewprimitivebehaviorspace-experiment-nameaddedallowingyoutogetthenameofthecurrentlyrunningexperimentNewprimitivestop-inspectingtostopinspectingagentsNewprimitivestop-inspecting-dead-agentsandmenuitemtostopinspectingdeadagents__includeskeywordnowenablestheIncludesbuttonwhengivenanemptyhooksaddedforextensionstowritecustomlogmessages

Bugfixes

user-one-ofwillnowsignalanerrorearlierwhenprovidedanemptylistofchoiceshsb,extract-hsb,andapproximate-hsbhavebeenupdatedtorepresenttruehsbconventionsnewdeprecatedprimitives__hsb-old,__extract-hsb-old,and__approximate-hsb-oldworkastheoldhsbprimitivesdidwhenoldermodelsusingthehsbprimitivesareopenedinNetLogo5.2,theywillbeauto-convertedtousethedeprecatedprimitivesextract-hsb--fixedbugwhereitdidn'tworkcorrectlyonrgblists

Modelchanges

NewSampleModels:ArtificialAnasazi,BacteriaFoodHunt,BacteriaHuntSpeeds,BeeSmart-HiveFinding,BugHuntDisruptions,BugHuntEnvironmentalChanges,BugHuntPredatorsandInvasiveSpecies-TwoRegions,HydrogenDiffusion3D,Lennard-Jones,PathsThereare46newmodelsinthenewIABMTextbookfolder:TurtlesCirclingSimple,AntsSimple,HeroesandCowards,LifeSimple,SimpleEconomy,4DLAextensions,4ElFarolExtensions,4FireExtensions,4SegregationExtensions,5WolfSheepExtensions,AgentsetEfficiency,AgentsetOrdering,Communication-T-TNetworkExample,PreferentialAttachmentSimple,RandomNetwork,TrafficBasicAdaptive,TrafficBasicUtility,TrafficGridGoal,SpreadofDisease,VotingComponentVerification,VotingSensitivityAnalysis,ArduinoExample,DiseaseWithAndroidAvoidanceHubNet,ExampleHubNet,RunExample,RunResultExample,SimpleMachineLearning,SimpleViralMarketing,TicketSales,SandpileSimpleNewmodelsinthenewAlternateVisualizationsfolder:Ethnocentrism-AlternativeVisualization,Flocking-AlternativeVisualizations,HeatDiffusion-Alternativevisualization,Virus-AlternativeVisualization,Virus-CircleVisualizationPromotedmodels:Honeycomb,MinorityGameManyotherbugfixesandupgrades

Version5.1.0(July2014)

bundlenewnetworkextensionFilemenuincludesrecentlyopenedfiles

deprecateappletssupportretinadisplayonnewMacBooks

Version5.0.4(March2013)

uploadmodelstotheModelingCommons

Version5.0(February2012)

features:opensource(GPLlicense;sourcecodeonlineathttps://github.com/NetLogo/NetLogo)newlicenseforSampleModelsandCurricularModelsisCreativeCommonsAttribution-NonCommercial-ShareAlikeinternationalcharacters(Unicode)supportedthroughoutapplicationGUIislocalizedinSpanish,Russian,andChinese(volunteertranslatorswanted)richformattingandimagesinInfotabsusingMarkdownplottingcodegoesinsideplotsinsteadofincodetabauthorablemodelspeed(targetframeratesetting)buttonsoptionallydisableuntilticksstarttranslucentcolorsin3DviewandNetLogo3D(forRGBcolorsonly)

languagechanges:"tasks"storecodetoberunlater

akafirst-classfunctions,closures,lambdanewprimitives:task,is-command-task?,is-reporter-task?theseprimitivesaccepttasks:run,runresult,foreach,map,reduce,filter,n-values,sort-by

improvedoveralllistperformance(manyoperationstakenear-constanttimeinsteadoflineartime)youmustusereset-tickstostartthetickcounterbeforeusingtickortick-advancenewprimitivessetup-plotsandupdate-plotsnewprimitivesort-onletsyousaye.g.,sort-on [size] turtlesnewprimitiveerrorcausesaruntimeerrorrandom-normalrejectsnegativestandarddeviations

HubNet:activitiescanrunheadlessnewprimitiveshubnet-clients-list,hubnet-kick-client,hubnet-kick-all-clientshubnet-set-client-interfacenolongerrequired

otherfixesandchanges:tabsrenamedtoInterface/Info/CodeCommandCenterallowsreporters,addsshowcommandautomaticallyNetLogo3Duses.nlogo3dsuffix,not.nlogoimport-worldismuchfasterstartupnolongerrunsheadlessorinbackgroundBehaviorSpacerunsfixed3DrenderingbugwheresmallturtlesweretoobrightMacapprunsin64bitmodebydefaultupgradedWindowsinstallerGoGoextensiongetting-startedexperiencenowsmootheronallplatforms

models:newSampleModels:Sandpile,Lightning,OsmoticPressure,RobbytheRobot,PreferentialAttachment3DnewCurricularModels:BugHuntConsumers,BugHuntPredatorsandInvasiveSpecies,PlantSpeciation,epiDEMBasic,epiDEMTravelandControl,Connected


ChemistryAtmospherenewCodeExamples:InfoTabExample,GoGoMonitorSimple

Version4.1.3(April2011)

matrixextensionbehaviorspace-run-number


parallelBehaviorSpacecontrollingAPIallowsembeddingautomaticcodeindentersearchableModelsLibrarytranslucentcolorsmini-viewsinagentmonitorsresize-world,set-patch-sizebitmap,QuickTimeextensionsindividualizedHubNetclientviewsbrowser-basedHubNetclient

Version4.0(September2007)

linkagentstickcounterviewupdatemodes(tick-based,continuous)speedsliderfastforwardsinputboxesininterfacetabincludemultiplesourcefilesRGBcolorssliderboundsmaybereportersHubNetclienteditorMathematica-NetLogolinkarray,table,profiler,GISextensionsmodelsrunfaster(partialcompilationtoJVMbytecode)logging

Version3.1(April2006)

topologies(optionalwrappingatworldedges)randomizedagentsetordering

Version3.0(September2005)

3Dview(for2Dmodels)formattedInfotabsSystemDynamicsModelerfollow,ride,watchdrawinglayerGoGoextension


"headless"modeforcommandlineoperation"actionkeys"totriggerbuttonsbykeypressesmakesQuickTimemoviesofmodelslet,carefully

Version2.0.2(August2004)

extensionsandcontrollingAPIssoundextension


fast,flicker-free,non-grid-basedgraphics

Version1.3(June2003)

run,runresult,map,foreach,filter,reduce

Version1.2(March2003)

computersasHubNetclients

Version1.1(July2002)

Applets

Version1.0(April2002)

firstfullrelease(afteraseriesofbetas)

SystemRequirements

NetLogorunsonalmostanycurrentcomputer.

IfyouhaveanytroublewithNetLogonotworking,seeContactingUs.

ApplicationRequirements

Windows

NetLogorunsonWindows10,Windows8,Windows7andVista.NetLogo5.2.1wasthelastversiontosupportWindowsXPandWindows2000.

TheNetLogoinstallerforWindowsincludesJava8forNetLogo'sprivateuseonly.Otherprogramsonyourcomputerarenotaffected.

MacOSX

MacOSX10.8.3ornewerisrequired.(NetLogo5.1wasthelastversiontosupport10.5and10.4;NetLogo5.2.1wasthelastversiontosupport10.6and10.7)

TheNetLogoapplicationcontainsadistributionoftheJava8runtimeforNetLogo'sprivateuseonly.Otherprogramsonyourcomputerwillnotbeaffected.

Linux

NetLogoshouldworkonstandardDebian-basedandRedHat-basedLinuxdistributions.TheNetLogotarballincludesacopyoftheJava8runtime.

StartNetLogobyrunningtheprovidedNetLogoexecutable.

3DRequirements

Occasionallyanolder,lesspowerfulsystemisnotabletousethe3DvieworNetLogo3D.Tryitandsee.

Somesystemscanuse3Dbutcan'tswitchtofull-screenmode.Itdependsonthegraphicscardorcontroller.(Forexample,theATIRadeonIGP345andIntel82845probablywillnotwork.)

32-bitor64-bit?

FormostusersonLinuxorWindows,the32-bitversionofNetLogoisthesimplestwaytoaworkingNetLogoinstallation.Advanceduserswillwanttounderstandtheadvantagesof64-bitNetLogoaswellashowtodeterminewhethertheirmachinemeetstherequirements.

Theprimaryadvantageofthe64-bitversionistheabilitytoaddadditionalheapspacebychangingthe"-Xmx"JVMoption.Formoreinformation,seeHowbigcanmymodelbe.YoumayalsofindithelpfultobrowseOracle'sdocumentationontheperformancecharacteristicsofthe64-bitJVM

http://www.oracle.com/technetwork/java/hotspotfaq-138619.html#64bit_performance

Torun64-bitNetLogo,youmustberunning64-bitWindows.TodeterminewhetheryourversionofWindowsis64-bit,seeIsmyPCrunningthe32-bitor64-bitversionofWindowsifyou'reusingWindowsVista,orWindows7,orWhichWindowsoperatingsystemamIrunning?ifyouarerunninganyotherversionofWindows.

ForLinuxusers,theeasiestwaytodeterminewhetheryouroperatingsystemis64-bitischeckingtheoutputof

uname -m

Iftheoutputshows"x86_64"or"amd64",youshouldbeabletorunthe64-bitversion.

http://windows.microsoft.com/en-us/windows7/find-out-32-or-64-bit

http://windows.microsoft.com/en-us/windows/which-operating-system

ContactingUs

FeedbackfromusersisessentialtousindesigningandimprovingNetLogo.We'dliketohearfromyou.

Website

Ourwebsiteatccl.northwestern.eduincludesourmailingaddressandphonenumber.Italsohasinformationaboutourstaffandourvariousresearchactivities.

Feedback,questions,etc.

ForhelpusingNetLogo,trythisgroup:http://groups.yahoo.com/group/netlogo-users/.

Ifyouhavefeedback,suggestions,orquestions,[email protected].

Reportingbugs

OurpublicbugtrackerisonGitHubathttps://github.com/NetLogo/NetLogo/issues.Youcanlookheretoreportanewbug,checkifabughasalreadybeenreported,andsoon.

Whensubmittingabugreport,pleasetrytoincludeasmuchofthefollowinginformationaspossible:

Acompletedescriptionoftheproblemandhowitoccurred.TheNetLogomodelorcodeyouarehavingtroublewith.Ifpossible,attachacompletemodel.(It'sbestifyoucanreducetheamountofcodeinthemodeltotheminimumnecessarytodemonstratethebug.)Yoursysteminformation:NetLogoversion,OSversion,Javaversion,andsoon.ThisinformationisavailablefromNetLogo's"AboutNetLogo"menuitem,thenclickingtheSystemtab.Anyerrormessagesthatweredisplayed.Pleasecopyandpastetheentireerrormessageintoyouremail,ormakeascreencaptureifyouareunabletocopyandpaste.

[email protected].

Opensource

NetLogoisfree,opensourcesoftware.Thesourcecodeishostedathttps://github.com/NetLogo/NetLogo.Contributionsfrominterestedusersarewelcome.

FordiscussionofNetLogoAPI'sandthedevelopmentofNetLogoitself,tryhttp://groups.google.com/group/netlogo-devel.

http://ccl.northwestern.edu/

http://groups.yahoo.com/group/netlogo-users/


https://github.com/NetLogo/NetLogo/issues



http://groups.google.com/group/netlogo-devel

SampleModel:Party

Thisactivitygetsyouthinkingaboutcomputermodelingandhowyoucanuseit.ItalsogivesyouinsightintoNetLogoitself.Weencouragebeginninguserstostarthere.

AtaParty

Haveyoueverbeenatapartyandnoticedhowpeopleclusteringroups?Youmayhavealsonoticedthatpeopledon'tjuststayinagroup.Astheycirculate,thegroupschange.Ifyouwatchedthesechangesovertime,youmightnoticepatterns.

Forexample,insocialsettings,peoplemayexhibitdifferentbehaviorthanatworkorhome.Individualswhoareconfidentwithintheirworkenvironmentmaybecomeshyandtimidatasocialgathering.Andotherswhoarereservedatworkmaybethe"partystarter"withfriends.

Thesepatternscandependonthetypeofgathering.Insomesettings,peoplearetrainedtoorganizethemselvesintomixedgroups;forexample,partygamesorschool-likeactivities.Butinanon-structuredatmosphere,peopletendtogroupinamorerandommanner.

Isthereanytypeofpatterntothiskindofgrouping?

Let'stakeacloserlookatthisquestionbyusingthecomputertomodelhumanbehaviorataparty.NetLogo's"Party"modellooksspecificallyatthequestionofgroupingbygenderatparties:whydogroupstendtoformthataremostlymen,ormostlywomen?

Let'suseNetLogotoexplorethisquestion.

Whattodo:

1. StartNetLogo.2. Choose"ModelsLibrary"fromtheFilemenu.

3. Openthe"SocialScience"folder.4. Clickonthemodelcalled"Party".5. Pressthe"open"button.6. Pressthe"setup"button.

Intheviewofthemodel,youwillseepinkandbluegroupswithnumbers:

Theselinesrepresentminglinggroupsataparty.Menareshownasblue,womenpink.Thenumbersarethesizesofthegroups.

Doallthegroupshaveaboutthesamenumberofpeople?

Doallthegroupshaveaboutthesamenumberofeachsex?

Let'ssayyouarehavingapartyandinvited150people.Youarewonderinghowpeoplewillgathertogether.Suppose10groupsformattheparty.

Howdoyouthinktheywillgroup?

Insteadofasking150ofyourclosestfriendstogatherandrandomlygroup,let'shavethecomputersimulatethissituationforus.

Whattodo:

1. Pressthe"go"button.(Pressing"go"againwillstopthemodelmanually.)2. Observethemovementofpeopleuntilthemodelstops.3. Watchtheplotstoseewhat'shappeninginanotherway.4. Usethespeedsliderifyouneedtoslowthemodeldown.

Nowhowmanypeopleareineachgroup?

Originally,youmayhavethought150peoplesplittinginto10groups,wouldresultinabout15peopleineachgroup.Fromthemodel,weseethatpeopledidnotdivideupevenlyintothe10groups.Instead,somegroupsbecameverysmall,whereasothergroupsbecameverylarge.Also,thepartychangedovertimefromallmixedgroupsofmenandwomentoallsingle-sexgroups.

Whatcouldexplainthis?

Therearelotsofpossibleanswerstothisquestionaboutwhathappensatrealparties.Thedesignerofthissimulationthoughtthatgroupsatpartiesdon'tjustformrandomly.Thegroupsaredeterminedbyhowtheindividualsatthepartybehave.Thedesignerchosetofocusonaparticularvariable,called"tolerance":

Toleranceisdefinedhereasthepercentageofpeopleoftheoppositesexanindividualis"comfortable"with.Iftheindividualisinagroupthathasahigherpercentageofpeopleoftheoppositesexthantheirtoleranceallows,thentheybecome"uncomfortable"andleavethegrouptofindanothergroup.

Forexample,ifthetolerancelevelissetat25%,thenmalesareonly"comfortable"ingroupsthatarelessthan25%female,andfemalesareonly"comfortable"ingroupsthatareless

than25%male.

Asindividualsbecome"uncomfortable"andleavegroups,theymoveintonewgroups,whichmaycausesomepeopleinthatgrouptobecome"uncomfortable"inturn.Thischainreactioncontinuesuntileveryoneatthepartyis"comfortable"intheirgroup.

Notethatinthemodel,"tolerance"isnotfixed.You,theuser,canusethetolerance"slider"totrydifferenttolerancepercentagesandseewhattheoutcomeiswhenyoustartthemodeloveragain.

Howtostartover:

1. Ifthe"go"buttonispressed(black),thenthemodelisstillrunning.Pressthebuttonagaintostopit.

2. Adjustthe"tolerance"slidertoanewvaluebydraggingitsredhandle.3. Pressthe"setup"buttontoresetthemodel.4. Pressthe"go"buttontostartthemodelrunningagain.

Challenge

Asthehostoftheparty,youwouldliketoseebothmenandwomenminglingwithinthegroups.Adjustthetoleranceslideronthesideoftheviewtogetallgroupstobemixedasanendresult.

Tomakesureallgroupsof10havebothsexes,atwhatlevelshouldwesetthetolerance?

Testyourpredictionsonthemodel.

Canyouseeanyotherfactorsorvariablesthatmightaffectthemaletofemaleratiowithineachgroup?

Makepredictionsandtestyourideaswithinthismodel.

Asyouaretestingyourhypotheses,youwillnoticethatpatternsareemergingfromthedata.Forexample,ifyoukeepthenumberofpeopleatthepartyconstantbutgraduallyincreasethetolerancelevel,moremixedgroupsappear.

Howhighdoesthetolerancevaluehavetobebeforeyougetmixedgroups?

Whatpercenttolerancetendstoproducewhatpercentageofmixing?

Thinkingwithmodels

UsingNetLogotomodelasituationlikeapartyallowsyoutoexperimentwithasysteminarapidandflexiblewaythatwouldbedifficulttodointherealworld.Modelingalsogivesyoutheopportunitytoobserveasituationorcircumstancewithlessprejudice,asyoucanexaminetheunderlyingdynamicsofasituation.Youmayfindthatasyoumodelmoreandmore,manyofyourpreconceivedideasaboutvariousphenomenawillbechallenged.Forexample,asurprisingresultofthePartymodelisthateveniftoleranceisrelativelyhigh,agreatdealofseparationbetweenthesexesoccurs.

Thisisaclassicexampleofan"emergent"phenomenon,whereagrouppatternresultsfrom

theinteractionofmanyindividuals.Thisideaof"emergent"phenomenacanbeappliedtoalmostanysubject.

Whatotheremergentphenomenacanyouthinkof?

ToseemoreexamplesandgainadeeperunderstandingofthisconceptandhowNetLogohelpslearnersexploreit,youmaywishtoexploreNetLogo'sModelsLibrary.Itcontainsmodelsthatdemonstratetheseideasinsystemsofallkinds.

ForalongerdiscussionofemergenceandhowNetLogohelpslearnersexploreit,see"ModelingNature'sEmergentPatternswithMulti-agentLanguages"(Wilensky,2001).

What'snext?

ThesectionoftheUserManualcalledTutorial#1:RunningModelsgoesintomoredetailabouthowtousetheothermodelsintheModelsLibrary.

Ifyouwanttolearnhowtoexplorethemodelsatadeeperlevel,Tutorial#2:CommandswillintroduceyoutotheNetLogomodelinglanguage.

Eventually,you'llbereadyforTutorial#3:Procedures.Thereyoucanlearnhowtoalterandextendexistingmodelstogivethemnewbehaviors,andyoucanstarttobuildyourownmodels.

http://ccl.northwestern.edu/papers/MEE/

Tutorial#1:Models

IfyoureadtheSampleModel:Partysection,yougotabriefintroductiontowhatit'sliketoexploreaNetLogomodel.Thissectionwillgointomoredepthaboutthefeaturesthatareavailablewhileyou'reexploringthemodelsintheModelsLibrary.

Throughoutallofthetutorials,we'llbeaskingyoutomakepredictionsaboutwhattheeffectsofmakingchangestothemodelswillbe.Keepinmindthattheeffectsareoftensurprising.Wethinkthesesurprisesareexcitingandprovideexcellentopportunitiesforlearning.

Youmaywanttoprintoutthetutorialstomakethemeasiertorefertowhileyou'reusingNetLogo.

SampleModel:WolfSheepPredation

We'llopenoneoftheSampleModelsandexploreitindetail.Let'stryabiologymodel:WolfSheepPredation,apredator-preypopulationmodel.

OpentheModelsLibraryfromtheFilemenu.

Choose"WolfSheepPredation"fromtheBiologysectionandpress"Open".

TheInterfacetabwillfillupwithlotsofbuttons,switches,slidersandmonitors.Theseinterfaceelementsallowyoutointeractwiththemodel.Buttonsareblue;theysetup,start,andstopthemodel.Slidersandswitchesaregreen;theyaltermodelsettings.Monitorsandplotsarebeige;theydisplaydata.

Ifyou'dliketomakethewindowlargersothateverythingiseasiertosee,youcanusetheZoommenu.

Whenyoufirstopenthemodel,youwillnoticethatthe"view"(thegraphicaldisplayoftheagentsinthemodel)isempty(allblack).Tobeginthemodel,youwillfirstneedtosetitup.

Pressthe"setup"button.

Whatdoyouseeappearintheview?

Pressthe"go"buttontostartthesimulation.

Asthemodelisrunning,whatishappeningtothewolfandsheeppopulations?

Pressthe"go"buttontostopthemodel.

ControllingtheModel:Buttons

Whenabuttonispressed,themodelrespondswithanaction.Abuttoncanbea"once"button,ora"forever"button.Youcantellthedifferencebetweenthesetwotypesofbuttonsbyasymbolonthefaceofthebutton.Foreverbuttonshavetwoarrowsinthebottomrightcorners,likethis:

Oncebuttonsdon'thavethearrows,likethis:

Oncebuttonsdooneactionandthenstop.Whentheactionisfinished,thebuttonpopsbackup.

Foreverbuttonsdoanactionoverandoveragain.Whenyouwanttheactiontostop,pressthebuttonagain.Itwillfinishthecurrentaction,thenpopbackup.

Mostmodels,includingWolfSheepPredation,haveaoncebuttoncalled"setup"andaforeverbuttoncalled"go".Manymodelsalsohaveaoncebuttoncalled"goonce"or"steponce"whichislike"go"exceptthatitadvancesthemodelbyonetick(timestep)insteadofoverandover.Usingaoncebuttonlikethisletsyouwatchtheprogressofthemodelmoreclosely.

Stoppingaforeverbuttonisthenormalwaytopauseorstopamodel.Afterpausingyoucanmakeitresumebypressingthebuttonagain.(Youcanalsostopamodelwiththe"Halt"itemontheToolsmenu,butyoushouldonlydothisifthemodelisstuckforsomereason.Using"Halt"mayinterruptthemodelinthemiddleofanaction,andastheresultthemodelcouldgetconfused.)

Ifyoulike,experimentwiththe"setup"and"go"buttonsintheWolfSheepPredationmodel.

Doyouevergetdifferentresultsifyourunthemodelseveraltimeswiththesamesettings?

Controllingspeed:SpeedSlider

Thespeedsliderallowsyoutocontrolthespeedofamodel,thatis,thespeedatwhichturtlesmove,patcheschangecolor,andsoon.

Whenyoumovetheslidertotheleftthemodelslowsdownsotherearelongerpausesbetweeneachtick(timestep).Thatmakesiteasiertoseewhatishappening.Youmightevenslowthemodeldownsofarastoseeexactlywhatasingleturtleisdoing.

Whenyoumovethespeedslidertotherightthemodelspeedsup.NetLogowillstartskippingframes,thatis,itwon'tupdatetheviewattheendofeverytick,onlysometicks.Updatingtakestime,sofewerviewupdatesmeansthemodelprogressesfaster.

Notethatifyoupushthespeedsliderwelltotheright,theviewmayupdatesoinfrequentlythatthemodelappearstohavesloweddown.Ithasn't,asyoucanseebywatchingthetickcounterraceahead.Onlythefrequencyofviewupdateshaslessened.

AdjustingSettings:SlidersandSwitches

Amodel'ssettingsletyouexploredifferentscenariosorhypotheses.Alteringthesettingsandthenrunningthemodeltoseehowitreactscangiveyouadeeperunderstandingofthephenomenabeingmodeled.

Switchesandslidersgiveyouaccesstoamodel'ssettings.HerearetheswitchesandslidersinWolfSheepPredation:

Let'sexperimentwiththeireffectonthebehaviorofthemodel.

OpenWolfSheepPredationifit'snotopenalready.Press"setup"and"go"andletthemodelrunforabout100ticks.(Thetickcountisshownabovetheview.)Stopthemodelbypressingthe"go"button.

Whathappenedtothesheepovertime?

Let'stakealookandseewhatwouldhappentothesheepifwechangeasetting.

Turnthe"grass?"switchon.Press"setup"and"go"andletthemodelrunforasimilaramountoftimeasbefore.

Whatdidtheswitchdo?Wastheoutcomethesameasyourpreviousrun?

Turningthe"grass?"switchonaffectedtheoutcomeofthemodel.Withtheswitchoff,theamountofgrassavailablealwaysstayedthesame.Thisisnotarealisticlookatthepredator-preyrelationship;sobysettingandturningonagrassregrowthrate,wewereabletomodelallthreefactors:sheep,wolfandgrasspopulations.

Anothertypeofsettingiscalledaslider.

Besidesswitches,amodelmayalsohavesliders.Whileaswitchhasonlytwovalues,onandoff,asliderhasawholerangeofnumericvalues.Forexample,the"initial-number-sheep"sliderhasaminimumvalueof0andamaximumvalueof250.Themodelcouldrunwith0sheeporitcouldrunwith250sheep,oranywhereinbetween.Trythisoutandseewhathappens.Asyoumovethemarkerfromtheminimumtothemaximumvalue,thenumberontherightsideofthesliderchanges;thisisthenumbertheslideriscurrentlysetto.

Let'sinvestigateWolfSheepPredation'ssliders.

ChangefromtheInterfacetotheInfotabtolearnwhateachofthismodels'slidersrepresents.

TheInfotaboffersguidanceandinsightintothemodel.Withinthistabyouwillfindanexplanationofthemodel,suggestionsonthingstotry,andotherinformation.YoumaywanttoreadtheInfotabbeforerunningamodel,oryoumightwanttojuststartexperimenting,thenlookattheInfotablater.

Whatwouldhappentothesheeppopulationifthereweremoresheepandlesswolvesinitially?

Turnthe"grass?"switchoff.Setthe"initial-number-sheep"sliderto100.Setthe"initial-number-wolves"sliderto20.Press"setup"andthen"go".Letthemodelrunforabout100ticks.

Tryrunningthemodelseveraltimeswiththesesettings.

Whathappenedtothesheeppopulation?

Didthisoutcomesurpriseyou?Whatotherslidersorswitchescanbeadjustedtohelpoutthesheeppopulation?

Set"initial-number-sheep"to80and"initial-number-wolves"to50.(Thisisclosetohowtheywerewhenyoufirstopenedthemodel.)Set"sheep-reproduce"to10.0%.Press"setup"andthen"go".Letthemodelrunforabout100timeticks.

Whathappenedtothewolvesinthisrun?

Whenyouopenamodel,alltheslidersandswitchesareonadefaultsetting.Ifyouopenanewmodelorexittheprogram,yourchangedsettingswillnotbesaved,unlessyouchoosetosavethem.

(Note:inadditiontoslidersandswitches,somemodelshavechoosersandinputboxes.TheWolfSheepPredationdoesn'thaveanyofthese,though.)

GatheringInformation:PlotsandMonitors

Theviewletsyouseewhat'sgoingoninamodel.NetLogoalsoprovideshasotherwaysofgivingyouinformationaboutmodelrun,suchasplotsandmonitors.

Plots

TheplotinWolfSheepPredationcontainsthreelines:sheep,wolves,andgrass/4.(Thegrasscountisdividedbyfoursoitdoesn'tmaketheplottootall.)Thelinesshowwhat'shappeninginthemodelovertime.Theplotlegendshowswhateachlineindicates.Inthiscase,it'sthepopulationcounts.

Whenaplotgetsclosetobecomingfilledup,thehorizontalaxisiscompressedandallofthedatafrombeforegetssqueezedintoasmallerspace.Inthisway,moreroomismadefortheplottogrow.

Ifyouwanttosavethedatafromaplottovieworanalyzeitinanotherapplication,usethe"ExportPlot"itemontheFilemenu.ItsavestheplotdatainaformatthatcanbyreadbackbyspreadsheetanddatabaseprogramssuchasExcel.Youcanalsoexportaplotbyright-clickingitandchoosing"Export..."fromthepopupmenu.

Monitors

Monitorsareanothermeansofdisplayinginformationfromamodel.HerearethemonitorsinWolfSheepPredation:

Themonitorsshowusthepopulationofsheepandwolves,andtheamountofgrass.(Remember,theamountofgrassisdividedbyfourtokeeptheplotfromgettingtootall.)

Thenumbersdisplayedinthemonitorschangeasthemodelruns,whereastheplotsshowyoudatafromthewholecourseofthemodelrun.

ControllingtheView

IntheInterfacetab,you'llseeatoolbarofcontrols.Someofthesecontrolaspectsoftheview.

Let'sexperimentwiththeeffectofthesecontrols.

Press"setup"andthen"go"tostartthemodelrunning.Asthemodelruns,movethespeedslidertotheleft.

Whathappens?

Thissliderishelpfulifamodelisrunningtoofastforyoutoseewhat'sgoingonindetail.

Movethespeedslidertothemiddle.Trymovingthespeedslidertotheright.Nowtrycheckinganduncheckingthe"viewupdates"checkbox.

Whathappens?

Fastforwardingthemodelandturningoffviewupdatesareusefulifyou'reimpatientandwantamodeltorunfaster.Fastforwarding(movingthespeedslidertotheright)dropsviewupdatessothemodelcanrunfast,sinceupdatingtheviewtakestimethatcouldbeusedforrunningthemodelitself.

Whenviewupdatesareoffcompletely,themodelcontinuestoruninthebackground,andplotsandmonitorsstillupdate.Butifyouwanttoseewhat'shappening,youneedtoturnviewupdatesbackonbyrecheckingthebox.Manymodelsrunmuchfasterwhenviewupdatesareoff.Forothers,itmakeslittledifference.

Thesizeoftheviewisdeterminedbyfiveseparatesettings:min-pxcor,max-pxcor,min-pycor,max-pycor,andpatchsize.Let'stakealookatwhathappenswhenwechangethesizeoftheviewinthe"WolfSheepPredation"model.

Therearemoremodelsettingsthanthere'sroomforinthetoolbar.The"Settings..."buttonletsyougettotherestofthesettings.

Pressthe"Settings..."buttoninthetoolbar.

Adialogwillopencontainingallthesettingsfortheview:

Whatarethecurrentsettingsformin-pxcor,max-pxcor,min-pycor,max-pycor,andpatchsize?

Press"cancel"tomakethiswindowgoawaywithoutchangingthesettings.Placeyourmousepointernextto,butstilloutsideof,theview.

Youwillnoticethatthepointerturnsintoacrosshair.

Holddownthemousebuttonanddragthecrosshairovertheview.

Theviewisnowselected,whichyouknowbecauseitisnowsurroundedbyagrayborder.

Dragoneofthesquareblack"handles".Thehandlesarefoundontheedgesandatthecornersoftheview.UnselecttheviewbyclickinganywhereinthewhitebackgroundoftheInterfacetab.Pressthe"Settings..."buttonagainandlookatthesettings.

Whatnumberschanged?

Whatnumbersdidn'tchange?

TheNetLogoworldisatwodimensionalgridof"patches".Patchesaretheindividualsquaresinthegrid.InWolfSheepPredation,whenthe"grass?"switchisontheindividualpatchesareeasilyseen,becausesomearegreen,othersbrown.

Thinkofthepatchesasbeinglikesquaretilesinaroomwithatilefloor.Bydefault,exactlyinthemiddleoftheroomisatilelabeled(0,0);meaningthatiftheroomwasdividedinhalfonewayandthentheotherway,thesetwodividinglineswouldintersectonthistile.Wenowhaveacoordinatesystemthatwillhelpuslocateobjectswithintheroom:

Howmanytilesawayisthe(0,0)tilefromtherightsideoftheroom?

Howmanytilesawayisthe(0,0)tilefromtheleftsideoftheroom?

InNetLogo,thenumberoftilesfromrighttoleftiscalledworld-width.Andthenumberoftilesfromtoptobottomisworld-height.Thesenumbersaredefinedbytop,bottom,leftandrightboundaries.

Inthesediagrams,max-pxcoris3,min-pxcoris-3,max-pycoris2andmin-pycoris-2.

Whenyouchangethepatchsize,thenumberofpatches(tiles)doesn'tchange,thepatchesonlygetlargerorsmallerintheview.

Let'slookattheeffectofchangingtheminimumandmaximumcoordinatesintheworld.

UsingtheSettingsdialogthatisstillopen,changemax-pxcorto30andmax-pycorvalueto10.Noticethatmin-pxcorandmin-pycorchangetoo.That'sbecausebydefaulttheorigin(0,0)isinthecenteroftheworld.

Whathappenedtotheshapeoftheview?

Pressthe"setup"button.

Nowyoucanseethenewpatchesyouhavecreated.

Edittheviewbypressingthe"Settings..."buttonagain.Changethepatchsizeto20andpress"OK".

Whathappenedtothesizeoftheview?Diditsshapechange?

Editingtheviewalsoletsyouchangeothersettings.Feelfreetoexperimentwiththese.

OnceyouaredoneexploringtheWolfSheepPredationmodel,youmaywanttotakesometimejusttoexploresomeoftheothermodelsavailableintheModelsLibrary.

ModelsLibrary

Thelibrarycontainsfoursections:SampleModels,CurricularModels,CodeExamples,andHubNetActivities.

SampleModels

TheSampleModelssectionisorganizedbysubjectareaandcurrentlycontainsmorethan200models.Wearecontinuouslyworkingonaddingnewmodelstoit,socomevisitthissectionatalaterdatetoviewthenewadditionstothelibrary.

SomeofthefoldersinSampleModelshavefoldersinsidethemlabeled"(unverified)".Thesemodelsarecompleteandfunctional,butarestillintheprocessofbeingreviewedforcontent,accuracy,andqualityofcode.

CurricularModels

ThesearemodelsdesignedtobeusedinschoolsinthecontextofcurriculadevelopedbytheCCLatNorthwesternUniversity.SomeofthesearemodelsarealsolistedunderSampleModels;othersareuniquetothissection.SeetheInfotabsofthemodelsformoreinformationonthecurriculatheygowith.

CodeExamples

ThesearesimpledemonstrationsofparticularfeaturesofNetLogo.They'llbeusefultoyoulaterwhenyou'reextendingexistingmodelsorbuildingnewones.Forexample,ifyouwantedtoaddahistogramtoyourmodel,you'dlookat"HistogramExample"tofindouthow.

HubNetActivities

Thissectioncontainsparticipatorysimulationsforusewithgroups.FormoreinformationaboutHubNet,seetheHubNetGuide.

What'sNext?

Ifyouwanttolearnhowtoexploremodelsatadeeperlevel,Tutorial#2:CommandswillintroduceyoutotheNetLogomodelinglanguage.

InTutorial#3:Proceduresyoucanlearnhowtoalterandextendexistingmodelsandbuildnewones.

Tutorial#2:Commands

Sofaryou'vesuccessfullynavigatedyourwaythroughopeningandrunningmodels,pressingbuttons,changingslidersandswitches,andgatheringinformationfromamodelusingplotsandmonitors.

Inthissection,thefocuswillstarttoshiftfromobservingmodelstomanipulatingmodels.Youwillstarttoseetheinnerworkingsofthemodelsandbeabletochangehowtheylook.

SampleModel:TrafficBasic

OpentheModelsLibrary(fromtheFilemenu).OpenTrafficBasic,foundinthe"SocialScience"section.Runthemodelforawhiletogetafeelforit.ConsulttheInfotabforanyquestionsyoumayhave.

Inthismodel,youwillnoticeoneredcarinastreamofbluecars.Thestreamofcarsareallmovinginthesamedirection.Everysooftenthey"pileup"andstopmoving.Thisismodelinghowtrafficjamscanformwithoutaspecificcauselikeanaccident.

Youmayalterthesettingsandobserveafewrunstogetafullerunderstandingofthemodel.

AsyouareusingtheTrafficBasicmodel,haveyounoticedanyadditionsyouwouldliketomaketothemodel?

LookingattheTrafficBasicmodel,youmaynoticetheenvironmentisfairlysimple;ablackbackgroundwithawhitestreetandnumberofbluecarsandoneredcar.Changesthatcouldbemadetothemodelinclude:changingthecolorandshapeofthecars,addingahouseorstreetlight,creatingastoplight,orevencreatinganotherlaneoftraffic.Someofthesesuggestedchangesarevisual,toenhancethelookofthemodel,whileothersaremorebehavioral.Wewillbefocusingmoreonthesimplerorcosmeticchangesthroughoutmostofthistutorial.(Tutorial#3willgointogreaterdetailaboutbehavioralchanges,whichrequirechangingtheCodetab.)

TomakethesesimplechangeswewillbeusingtheCommandCenter.

CommandCenter

TheCommandCenterisfoundintheInterfacetab.Itallowsyoutoentercommandsordirectionstoamodel.CommandsareinstructionsyoucangivetoNetLogo'sagents:turtles,patches,links,andtheobserver.

InTrafficBasic:

Pressthe"setup"button.LocatetheCommandCenter.

ClickthemouseinthewhiteboxatthebottomoftheCommandCenter.Typethetextshownhere:

Pressthereturnkey.

WhathappenedtotheView?

YoumayhavenoticedthebackgroundoftheViewhasturnedallyellowandthestreethasdisappeared.

Whydidn'tthecarsturnyellowtoo?

Lookingbackatthecommandthatwaswritten,weaskedonlythepatchestochangetheircolor.Inthismodel,thecarsarerepresentedbyadifferentkindofagent,called"turtles".Therefore,thecarsdidnotreceivetheseinstructionsandthusdidnotchange.

WhathappenedintheCommandCenter?

YoumayhavenoticedthatthecommandyoujusttypedisnowdisplayedintheCommandCenterasshownbelow:

TypeinthebottomoftheCommandCenterthetextshownbelow:

Wastheresultwhatyouexpected?

Theviewshouldhaveayellowbackgroundwithalineofbrowncarsinthemiddle:

TheNetLogoworldisatwodimensionalworldthatismadeupofturtles,patches,links,andanobserver.Thepatchesarethegroundoverwhichtheturtlesmove.Linksareconnectionsbetweenturtles.Andtheobserverisabeingthatoverseeseverythingthatisgoingon.(Formorespecifics,refertotheNetLogoProgrammingGuide.)

IntheCommandCenteryoucangivecommandstoanyofthesetypesofagents.Youchoosewhichtypetotalktobyusingthepopupmenulocatedinthebottomleftcorner.Youcanalsousethetabkeyonyourkeyboardtocyclethroughthedifferenttypes.

IntheCommandCenter,clickonthe"observer>"inthebottomleftcorner:

Choose"turtles"fromthepopupmenu.Typeset color pinkandpressreturn.Pressthetabkeyuntilyousee"patches>"inthebottomleftcorner.Typeset pcolor whiteandpressreturn.

WhatdoestheViewlooklikenow?

Doyounoticeanydifferencesbetweenthesetwocommandsandtheobservercommandsfromearlier?

Theobserveroverseestheworldandthereforecangiveacommandtothepatchesorturtlesusingask.Likeinthefirstexample(observer>ask patches [set pcolor yellow]),theobserverhastoaskthepatchestosettheirpcolortoyellow.Butwhenacommandisdirectlygiventoagroupofagentslikeinthesecondexample(patches>set pcolor white),youonlyhavetogivethecommanditself.

Press"setup".

Whathappened?

WhydidtheViewrevertbacktotheoldversion,withtheblackbackgroundandwhiteroad?Uponpressingthe"setup"button,themodelwillreconfigureitselfbacktothesettingsoutlinedintheCodetab.TheCommandCenterdoesn'tpermanentlychangethemodel.ItallowsyoutomanipulatetheNetLogoworlddirectlytofurtheranswerthose"Whatif"questionsthatpop

upasyouareinvestigatingthemodels.(TheCodetabisexplainedinthenexttutorial,andintheProgrammingGuide.)

NowthatwehavefamiliarizedourselveswiththeCommandCenter,let'slookatsomemoredetailsabouthowcolorsworkinNetLogo.

Workingwithcolors

Youmayhavenoticedintheprevioussectionthatweusedtwodifferentwordsforchangingcolor:colorandpcolor.

Whatisthedifferencebetweencolorandpcolor?

Choose"turtles"fromthepopupmenuintheCommandCenter(orusethetabkey).Typeset color blueandpressreturn.

Whathappenedtothecars?

Thinkaboutwhatyoudidtomakethecarsturnblue,andtrytomakethepatchesturnred.

Ifyoutrytoaskthepatchestoset color red,anerrormessageoccurs:

Typeset pcolor redinsteadandpressreturn.

Wecallcolorandpcolor"variables".Somecommandsandvariablesarespecifictoturtlesandsomearespecifictopatches.Forexample,thecolorvariableisaturtlevariable,whilethepcolorvariableisapatchvariable.

Goaheadandpracticealteringthecolorsoftheturtlesandpatchesusingthesetcommandandthesetwovariables.

Tobeabletomakemorechangestothecolorsofturtlesandpatches,orshallwesaycarsandbackgrounds,weneedtogainalittleinsightintohowNetLogodealswithcolors.

InNetLogo,colorshaveanumericvalue.Inalloftheexerciseswehavebeenusingthenameofthecolor.ThisisbecauseNetLogorecognizes16differentcolornames.ThisdoesnotmeanthatNetLogoonlyrecognizes16colors.Therearemanyshadesinbetweenthesecolorsthatcanbeusedtoo.Here'sachartthatshowsthewholeNetLogocolorspace:

Togetanintermediateshade,yourefertoitbyanumberinstead,orbyaddingorsubtractinganumberfromaname.Forexample,whenyoutypeset color red,thisdoesthesamethingasifyouhadtypedset color 15.Andyoucangetalighterordarkerversionofthesamecolorbyusinganumberthatisalittlelargeroralittlesmaller,asfollows.

Choose"patches"fromthepopupmenuintheCommandCenter(orusethetabkey).Typeset pcolor red - 2(Thespacingaroundthe"-"isimportant.)

Bysubtractingfromred,youmakeitdarker.

Typeset pcolor red + 2

Byaddingtored,youmakeitlighter.

Youcanusethistechniqueonanyofthecolorslistedinthechart.

AgentMonitorsandAgentCommanders

Inthepreviousactivity,weusedthesetcommandtochangethecolorsofallthecars.Butifyourecall,theoriginalmodelcontainedoneredcaramongstagroupofbluecars.Let'slookathowtochangeonlyonecar'scolor.

Press"setup"togettheredcartoreappear.Right-clickontheredcar.

Ifthereisanotherturtleclosetotheredturtleyou'llseemorethanoneturtlelistedatthebottomofthemenu.Moveyourmouseovertheturtleselections,noticewhenyourmousehighlightsaturtlemenuitemthatturtleishighlightedintheview.Select"inspectturtle"fromthesub-menufortheredturtle.

Aturtlemonitorforthatcarwillappear:

Themini-viewatthetopoftheagentmonitorwillalwaysstaycenteredonthisagent.Youcanzoomtheviewinandoutusingthesliderbelowtheviewandyoucanwatchthisturtleinthemainviewbypressingthe"watch-me"button.

Takingacloserlookatthisturtlemonitor,wecanseeallofthevariablesthatbelongtotheredcar.Avariableisalocationthatholdsavalue.

Let'stakeacloserlookattheturtlemonitor:

Whatisthisturtle'swhonumber?

Whatcoloristhisturtle?

Whatshapeisthisturtle?

Thisturtlemonitorisshowingaturtlewhothathasawhonumberof0,acolorof15(red--seechartabove),andtheshapeofacar.

Therearetwootherwaystoopenaturtlemonitorbesidesright-clicking.Onewayistochoose"TurtleMonitor"fromtheToolsmenu,thentypethewhonumberoftheturtleyouwanttoinspectintothe"who"fieldandpressreturn.Theotherwayistotypeinspect turtle0(orotherwhonumber)intotheCommandCenter.

Youcloseaturtlemonitorbyclickingthecloseboxintheupperlefthandcorner(Mac)orupperrighthandcorner(otheroperatingsystems).

NowthatweknowmoreaboutAgentMonitors,wehavethreewaystochangeanindividualturtle'scolor.

OnewayistousetheboxcalledanAgentCommanderfoundatthebottomofanAgentMonitor.Youtypecommandshere,justlikeintheCommandCenter,butthecommandsyoutypehereareonlydonebythisparticularturtle.

IntheAgentCommanderoftheTurtleMonitorforturtle0,typeset colorpink.

WhathappensintheView?

DidanythingchangeintheTurtleMonitor?

Asecondwaytochangeoneturtle'scoloristogodirectlytothecolorvariableintheTurtleMonitorandchangethevalue.

Selectthetexttotherightof"color"intheTurtleMonitor.Typeinanewcolorsuchasgreen + 2.

Whathappened?

Thethirdwaytochangeanindividualturtle'sorpatch'scoloristousetheobserver.Since,theobserveroverseestheNetLogoworld,itcangivecommandsthataffectindividualturtles,aswellasgroupsofturtles.

IntheCommandCenter,select"observer"fromthepopupmenu(orusethetabkey).Typeask turtle 0 [set color blue]andpressreturn.

Whathappens?

JustasthereareTurtleMonitors,therearealsoPatchMonitors.PatchmonitorsworkverysimilarlytoTurtleMonitors.

Canyoumakeapatchmonitoranduseittochangethecolorofasinglepatch?

Ifyoutrytohavetheobserverask patch 0 [set pcolor blue],you'llgetanerrormessage:

Toaskanindividualturtletodosomething,weuseitswhonumber.Butpatchesdon'thavewhonumbers,thereforeweneedtorefertothemsomeotherway.

Remember,patchesarearrangedonacoordinatesystem.Twonumbersareneededtoplotapointonagraph:anx-axisvalueanday-axisvalue.Patchlocationsaredesignatedinthesamewayasplottingapoint.

Openapatchmonitorforanypatch.

Themonitorshowsthatforthepatchinthepicture,itspxcorvariableis-19anditspycorvariableis0.Ifwegobacktotheanalogyofthecoordinateplaneandwantedtoplotthispoint,thepointwouldbefoundonthexaxisleftoftheorigin,wherex=-19andy=0.

Totellthisparticularpatchtochangecolor:

Inthebottomofthepatchmonitor,enterset pcolor blueandpressreturn.

Typingacommandinaturtleorpatchmonitoraddressesonlythatturtleorpatch.

YoucanalsotalktoasinglepatchfromtheCommandCenter:

IntheCommandCenter,enterask patch -19 0 [set pcolor green]andpressreturn.

What'sNext?

Atthispoint,youmaywanttotakesometimetotryoutthetechniquesyou'velearnedonsomeoftheothermodelsintheModelsLibrary.

InTutorial#3:Proceduresyoucanlearnhowtoalterandextendexistingmodelsandbuildyourownmodels.

Tutorial#3:Procedures

Thistutorialleadsyouthroughtheprocessofbuildingacompletemodel,builtupinstages,witheverystepexplainedalongtheway.

Agentsandprocedures

InTutorial#2,youlearnedhowtousethecommandcenterandagentmonitorstoinspectandmodifyagentsandmakethemdothings.Nowyou'rereadytolearnabouttherealheartofaNetLogomodel:theCodetab.

You'veseenthatagentsinNetLogoaredividedintopatches,turtles,links,andtheobserver.Patchesarestationaryandarrangedinagrid.Turtlesmoveoverthatgrid.Linksconnecttwoturtles.Theobserveroverseeseverythingthat'sgoingonanddoeswhatevertheturtles,patchesandlinkscan'tdoforthemselves.

AllfourtypesofagentscanrunNetLogocommands.Allfourcanalsorun"procedures".AprocedurecombinesaseriesofNetLogocommandsintoasinglenewcommandthatyoudefine.

Youwillnowlearntowriteproceduresthatmaketurtlesmove,eat,reproduce,anddie.Youwillalsolearnhowtomakemonitors,sliders,andplots.Themodelwe'llbuildisasimpleecosystemmodelnotunlikeWolfSheepPredationfromTutorial#1.

Makingthesetupbutton

Tostartanewmodel,select"New"fromtheFilemenu.Thenbeginbycreatingasetupbutton:

Clickthe"Add"iconinthetoolbaratthetopoftheInterfacetab.OnthemenunexttoAdd,selectButton(ifitisn'talreadyselected).ClickwhereveryouwantthebuttontoappearintheemptywhiteareaoftheInterfacetab.Adialogboxforeditingthebuttonopens.Typesetupintheboxlabeled"Commands".PresstheOKbuttonwhenyou'redone;thedialogboxcloses.

Nowyouhaveasetupbutton.Pressingthebuttonrunsaprocedurecalled"setup".AprocedureisasequenceofNetLogocommandsthatweassignanewname.We'lldefinethatproceduresoon,butwehaven'tyet.Thebuttonreferstoaprocedurethatdoesn'texist,sothebuttonturnsred:

Ifyouwanttoseetheactualerrormessage,clickthebutton.

Nowwe'llcreatethe"setup"procedure,sotheerrormessagewillgoaway:

SwitchtotheCodetab.Typethefollowing:

to setup clear-all create-turtles 100 [ setxy random-xcor random-ycor ] reset-ticksend

Whenyou'redone,theCodetablookslikethis:

Notethatsomelinesareindented.Mostpeoplefindithelpfultoindenttheircode.Itisn'tmandatory,butitmakesthecodeeasiertoreadandchange.

Yourprocedurebeginswithtoandendswithend.Everyprocedurebeginsandendswiththesewords.

Let'slookatwhatyoutypedinandseewhateachlineofyourproceduredoes:

to setupbeginsdefiningaprocedurenamed"setup".clear-allresetstheworldtoaninitial,emptystate.Allthepatchesturnblackandanyturtlesyoumighthavecreateddisappear.Basically,itwipestheslatecleanforanewmodelrun.create-turtles 100creates100turtles.Theystartoutstandingattheorigin,thatis,thecenterofpatch0,0.Aftercreate-turtleswecanputcommandsforthenewturtlestorun,enclosedbysquarebrackets.setxy random-xcor random-ycorisacommandusing"reporters".Areporter,asopposedtoacommand,reportsaresult.Firsteachturtlerunsthereporterrandom-xcorwhichwillreportarandomnumberfromtheallowablerangeofturtlecoordinatesalongtheXaxis.Theneachturtlerunsthereporterrandom-ycor,samefortheYaxis.Finallyeachturtlerunsthesetxycommandwiththosetwonumbersasinputs.Thatmakestheturtlemovetothepointwiththosecoordinates.reset-ticksstartsthetickcounter,nowthatsetupisotherwisecomplete.endcompletesthedefinitionofthe"setup"procedure.

Whenyou'redonetyping,switchtotheInterfacetabandpressthesetupbuttonyoumadebefore.Youwillseetheturtlesscatteredaroundtheworld:

Presssetupacouplemoretimes,andseehowthearrangementofturtlesisdifferenteachtime.Notethatsometurtlesmayberightontopofeachother.

Thinkabitaboutwhatyouneededtodotomakethishappen.Youneededtomakeabuttonintheinterfaceandmakeaprocedurethatthebuttonuses.Thebuttononlyworkedonceyoucompletedbothoftheseseparatesteps.Intheremainderofthistutorial,youwilloftenhavetocompletetwoormoresimilarstepstoaddanotherfeaturetothemodel.Ifsomethingdoesn'tappeartoworkafteryoucompletedwhatyouthoughtisthefinalstepforthatnewfeature,continuetoreadaheadtoseeifthereisstillmoretodo.Afterreadingaheadforacoupleofparagraphs,youshouldthengobackoverthedirectionstoseeifthereisanystepyoumighthavemissed.

Switchingtotick-basedviewupdates

Nowthatwe'reusingthetickcounter(withreset-ticks),weshouldtellNetLogothatitonlyneedstoupdatetheviewoncepertick,insteadofcontinuouslyupdatingit.

Findtheviewupdatesmenu.It'sabovetheviewandbydefaultsays"continuous".Choose"onticks"instead.

Thismakesyourmodelrunfasterandensuresaconsistentappearance(sincetheupdateswillhappenatconsistenttimes).SeetheProgrammingGuideforafullerdiscussionofviewupdates.

Makingthegobutton

Nowmakeabuttoncalled"go".Followthesamestepsyouusedtomakethesetupbutton,except:

ForCommandsentergoinsteadofsetup.Checkthe"Forever"checkboxintheeditdialog.Checkthe"Disableuntilticksstart"checkboxtoo.

The"Forever"checkboxmakesthebuttonstaydownoncepressed,soitscommandsrunoverandoveragain,notjustonce.

The"Disableuntilticksstart"preventsyoufrompressinggobeforesetup.

ThenaddagoproceduretotheCodetab:

to go move-turtles tickend

tickisaprimitivethatadvancesthetickcounterbyonetick.

Butwhatismove-turtles?Isitaprimitive(inotherwords,built-intoNetLogo)?No,it'sanotherprocedurethatyou'reabouttoadd.Sofar,youhaveintroducedtwoproceduresthatyouaddedyourself:setupandgo.

Addthemove-turtlesprocedureafterthegoprocedure:

to go

move-turtles tickend

to move-turtles ask turtles [ right random 360 forward 1 ]end

Notetherearenospacesaroundthehypheninmove-turtles.InTutorial#2weusedred - 2,withspaces,inordertosubtracttwonumbers,butherewewantmove-turtles,withoutspaces.The"-"combines"move"and"turtles"intoasinglename.

Hereiswhateachcommandinthemove-turtlesproceduredoes:

ask turtles [ ... ]saysthateachturtleshouldrunthecommandsinthebrackets.right random 360isanothercommandthatusesareporter.First,eachturtlepicksarandomwholenumberbetween0and359.(randomdoesn'tincludethenumberyougiveitasapossibleresult.)Thentheturtleturnsrightthisnumberofdegrees.forward 1makestheturtlemoveforwardonestep.

Whycouldn'twehavejustwrittenallofthesecommandsingoinsteadofinaseparateprocedure?Wecouldhave,butduringthecourseofbuildingyourproject,it'slikelythatyou'lladdmanyotherparts.We'dliketokeepgoassimpleaspossible,sothatitiseasytounderstand.Eventually,itwillincludemanyotherthingsyouwanttohavehappenasthemodelruns,suchascalculatingsomethingorplottingtheresults.Eachofthesethingstodowillhaveitsownprocedureandeachprocedurewillhaveitsownuniquename.

The'go'buttonyoumadeintheInterfacetabisaforeverbutton,meaningthatitwillcontinuallyrunitscommandsuntilyoushutitoff(byclickingonitagain).Afteryouhavepressed'setup'once,tocreatetheturtles,pressthe'go'button.Watchwhathappens.Turnitoff,andyou'llseethatalltheturtlesstopintheirtracks.

Notethatifaturtlemovesofftheedgeoftheworld,it"wraps",thatis,itappearsontheotherside.(Thisisthedefaultbehavior.Itcanbechanged;seetheTopologysectionoftheProgrammingGuideformoreinformation.)

Experimentingwithcommands

Wesuggestyoustartexperimentingwithotherturtlecommands.

TypecommandsintotheCommandCenter(liketurtles> set color red),oraddcommandstosetup,go,ormove-turtles.

NotethatwhenyouentercommandsintheCommandCenter,youmustchooseturtles>,patches>,links>,orobserver>inthepopupmenuontheleft,dependingonwhichagentsaregoingtorunthecommands.It'sjustlikeusingask turtlesorask patches,butsavestyping.Youcanalsousethetabkeytoswitchagenttypes,whichyoumightfindmoreconvenientthanusingthemenu.

Youmighttrytypingturtles>pen-downintotheCommandCenterandthenpressingthegobutton.

Also,insidethemove-turtlesprocedureyoucantrychangingright random 360toright random 45.

Playaround.It'seasyandtheresultsareimmediateandvisible--oneofNetLogo'smanystrengths.

Whenyoufeelyou'vedoneenoughexperimentingfornow,you'rereadytocontinueimprovingthemodelyouarebuilding.

Patchesandvariables

Nowwe'vegot100turtlesaimlesslymovingaround,completelyunawareofanythingelsearoundthem.Let'smakethingsalittlemoreinterestingbygivingtheseturtlesanicebackgroundagainstwhichtomove.

Gobacktothesetupprocedure.Wecanrewriteitasfollows:

to setup clear-all setup-patches setup-turtles reset-ticksend

Thenewdefinitionofsetupreferstotwonewprocedures.Todefinesetup-patches,addthis:

to setup-patches ask patches [ set pcolor green ]end

Thesetup-patchesproceduresetsthecolorofeverypatchtogreentostartwith.(Aturtle'scolorvariableiscolor;apatch'sispcolor.)

Theonlypartremaininginournew'setup'thatisstillundefinedissetup-turtles.

Addthisproceduretoo:

to setup-turtles create-turtles 100 ask turtles [ setxy random-xcor random-ycor ]

end

Didyounoticethatthenewsetup-turtlesprocedurehasmostofthesamecommandsastheoldsetupprocedure?

SwitchbacktotheInterfacetab.Pressthesetupbutton.

Voila!AlushNetLogolandscapecompletewithturtlesandgreenpatchesappears:

Afterseeingthenewsetupprocedureworkafewtimes,youmayfindithelpfultoreadthroughtheproceduredefinitionsagain.

Turtlevariables

Sowehavesometurtlesrunningaroundonalandscape,buttheyaren'tdoinganythingwithit.Let'saddsomeinteractionbetweentheturtlesandthepatches.

We'llmaketheturtleseat"grass"(thegreenpatches),reproduce,anddie.Thegrasswillgraduallygrowbackafteritiseaten.

We'llneedawayofcontrollingwhenaturtlereproducesanddies.We'lldeterminethatbykeepingtrackofhowmuch"energy"eachturtlehas.Todothatweneedtoaddanewturtlevariable.

You'vealreadyseenbuilt-inturtlevariableslikecolor.Tomakeanewturtlevariable,weaddaturtles-owndeclarationatthetopoftheCodetab,beforealltheprocedures.Callitenergy:

turtles-own [energy]

to go move-turtles eat-grass tickend

Let'susethisnewlydefinedvariable(energy)toallowtheturtlestoeat.

SwitchtotheCodetab.Rewritethegoprocedureasfollows:

to go move-turtles eat-grass tickend

Addaneweat-grassprocedure:

to eat-grass ask turtles [ if pcolor = green [ set pcolor black set energy energy + 10 ] ]end

Weareusingtheifcommandforthefirsttime.Lookatthecodecarefully.Eachturtle,whenitrunsthesecommands,comparesthevalueofthepatchcoloritison(pcolor)tothevalueforgreen.(Aturtlehasdirectaccesstothevariablesofthepatchitisstandingon.)Ifthepatchcolorisgreen,thecomparisonreportstrue,andonlythenwilltheturtlerunthecommandsinsidethebrackets(otherwiseitskipsthem).Thecommandsmaketheturtlechangethepatchcolortoblackandincreaseitsownenergyby10.Thepatchturnsblacktosignifythatthegrassatthatspothasbeeneaten.Andtheturtleisgivenmoreenergy,fromhavingjusteaten.

Next,let'smakethemovementofturtlesuseupsomeoftheturtle'senergy.

Rewritemove-turtlesasfollows:

to move-turtles ask turtles [ right random 360 forward 1 set energy energy - 1 ]end

Aseachturtlewanders,itwillloseoneunitofenergyateachstep.

SwitchtotheInterfacetabnowandpressthesetupbuttonandthegobutton.

You'llseethepatchesturnblackasturtlestraveloverthem.

Monitors

NextyouwillcreatetwomonitorsintheInterfacetabwiththetoolbar.(Youmakethemjustlikebuttonsandsliders,usingtheAddicononthetoolbar.)Let'smakethefirstmonitornow.

CreateamonitorbyclickingtheAddicononthetoolbar,selectingMonitornexttoit,andclickingonanopenspotintheInterface.

Adialogboxwillappear.

Inthedialogtype:count turtles(seeimagebelow).PresstheOKbuttontoclosethedialog.

turtlesisan"agentset",thesetofallturtles.counttellsushowmanyagentsareinthatset.

Let'smakethesecondmonitornow:

CreateamonitorbyclickingtheAddicononthetoolbar,selectingMonitornexttoit,andclickingonanopenspotintheInterface.

Adialogboxwillappear.

IntheReportersectionofthedialogboxtype:count patches with [pcolor = green](seeimagebelow).IntheDisplaynamesectionofthedialogboxtype:green patchesPresstheOKbuttontoclosethedialogbox.

Herewe'reusingcountagaintoseehowmanyagentsareinanagentset.patchesisthesetofallthepatches,butwedon'tjustwanttoknowhowmanypatchestherearetotal,wewanttoknowhowmanyofthemaregreen.That'swhatwithdoes;itmakesasmalleragentsetofjustthoseagentsforwhomtheconditioninthebracketsistrue.Theconditionispcolor = green,sothatgivesusjustthegreenpatches.

Nowwehavetwomonitorsthatwillreporthowmanyturtlesandgreenpatcheswehave,tohelpustrackwhat'sgoingoninourmodel.Asthemodelruns,thenumbersinthemonitorswillautomaticallychange.

Usethesetupandgobuttonsandwatchthenumbersinthemonitorschange.

Switchesandlabels

Theturtlesaren'tjustturningthepatchesblack.They'realsogainingandlosingenergy.Asthemodelruns,tryusingaturtlemonitortowatchoneturtle'senergygoupanddown.

Itwouldbenicerifwecouldseeeveryturtle'senergyallthetime.Wewillnowdoexactlythat,andaddaswitchsowecanturntheextravisualinformationonandoff.

ClickontheAddicononthetoolbar(intheInterfacetab).SelectSwitchfromthemenunexttoAdd.Clickonanopenspotintheinterface.

Adialogwillappear.

IntotheGlobalvariablefield,typeshow-energy?Don'tforgettoincludethequestionmarkinthename.(Seeimagebelow.)

Nowgobacktothe'go'procedureusingtheCodetabwiththeToolbar.Rewritetheeat-grassprocedureasfollows:

to eat-grass ask turtles [ if pcolor = green [ set pcolor black set energy energy + 10 ] ifelse show-energy? [ set label energy ] [ set label "" ] ]end

Theeat-grassprocedureintroducestheifelsecommand.Lookatthecodecarefully.Eachturtle,whenitrunsthesenewcommands,checksthevalueofshow-energy?(determinedbytheswitch).Iftheswitchison,comparisonistrueandtheturtlewillrunthecommandsinsidethefirstsetofbrackets.Inthiscase,itassignsthevaluefortheenergytothelabeloftheturtle.Ifthecomparisonisfalse(theswitchisoff)thentheturtlerunsthecommandsinsidethesecondsetofbrackets.Inthiscase,itremovesthetextlabels(bysettingthelabeloftheturtletobenothing).

(InNetLogo,apieceoftextiscalleda"string",shortforstringofcharacters.Astringisasequenceoflettersorothercharacters,writtenbetweendoublequotes.Herewehavetwodoublequotesrightnexttoeachother,withnothinginbetweenthem.That'sanemptystring.Ifaturtle'slabelisanemptystring,notextisattachedtotheturtle.)

TestthisintheInterfacetab,byrunningthemodel(usingthesetupandgobuttons)switchingtheshow-energy?switchbackandforth.

Whentheswitchison,you'llseetheenergyofeachturtlegoupeachtimeiteatsgrass.You'llalsoseeitsenergygoingdownwheneveritmoves.

Moreprocedures

Nowourturtlesareeating.Let'smakethemreproduceanddie,too.Andlet'smakethegrassgrowback.We'lladdallthreeoftheseofthesebehaviorsnow,bymakingthreeseparateprocedures,oneforeachbehavior.

GototheCodetab.Rewritethegoprocedureasfollows:

to go move-turtles eat-grass reproduce check-death regrow-grass tickend

Addtheproceduresforreproduce,check-death,andregrow-grassasshownbelow:

to reproduce ask turtles [ if energy > 50 [ set energy energy - 50 hatch 1 [ set energy 50 ] ] ]end

to check-death ask turtles [ if energy <= 0 [ die ] ]end

to regrow-grass ask patches [ if random 100 < 3 [ set pcolor green ] ]end

Eachoftheseproceduresusestheifcommand.Eachturtle,whenitrunscheck-deathitwillchecktoseeifitsenergyislessorequalto0.Ifthisistrue,thentheturtleistoldtodie(dieisaNetLogoprimitive).

Wheneachturtlerunsreproduce,itchecksthevalueoftheturtle'senergyvariable.Ifitisgreaterthan50,thentheturtlerunsthecommandsinsidethefirstsetofbrackets.Inthiscase,itdecreasestheturtle'senergyby50,then'hatches'anewturtlewithanenergyof50.ThehatchcommandisaNetLogoprimitivewhichlookslikethis:hatchnumber[commands].Thisturtlecreatesnumbernewturtles,eachidenticaltoitsparent,andasksthenewturtle(s)thathavebeenhatchedtoruncommands.Youcanusethecommandstogivethenewturtlesdifferentcolors,headings,orwhatever.Inourcasewerunonecommand.Wesettheenergyforthenewlyhatchedturtletobe50.

Wheneachpatchrunsregrow-grassitwillchecktoseeifarandomintegerfrom0to99islessthan3.Ifso,thepatchcolorissettogreen.Thiswillhappen3%ofthetime(onaverage)foreachpatch,sincetherearethreenumbers(0,1,and2)outof100possiblethatarelessthan3.

SwitchtotheInterfacetabnowandpressthesetupandgobuttons.

Youshouldseesomeinterestingbehaviorinyourmodelnow.Someturtlesdieoff,somenewturtlesarecreated(hatched),andsomegrassgrowsback.Thisisexactlywhatwesetouttodo.

Ifyoucontinuetowatchyourmonitorsinyourmodel,youwillseethatthecountturtlesandgreenpatchesmonitorsbothfluctuate.Isthispatternoffluctuationpredictable?Istherearelationshipbetweenthevariables?

It'dbeniceifwehadaeasierwaytotrackthechangesinthemodelbehaviorovertime.NetLogoallowsustoplotdataaswegoalong.Thatwillbeournextstep.

Plotting

Tomakeplottingwork,we'llneedtocreateaplotintheInterfacetabandputsomecommandsinsideit.

Thecommandsweputintheplotswillrunautomaticallywhenoursetupprocedurecallsreset-ticksandwhenourgoprocedurecallstick.

CreateaplotbyclickingtheAddicononthetoolbar,selectingPlotnexttoit,andclickingonanopenspotintheInterface.SetitsNameto"Totals"(seeimagebelow)SettheXaxislabelto"time"SettheYaxislabelto"totals"Changethenameofthe"default"pento"turtles".Enterplot count turtlesunderPenUpdateCommands.Pressthe"AddPen"button.Changethenameofthenewpento"grass".Enterplot count patches with [pcolor = green] underPenUpdateCommands.

Whenyou'redone,thedialogshouldlooklikethis:

PressOKinthePlotdialogtofinishediting.

NotethatwhenyoucreatetheplotyoucanalsosettheminimumandmaximumvaluesontheXandYaxes.You'llwanttoleavethe"AutoScale"checkboxchecked,sothatifanythingyouplotexceedstheminimumandmaximumvaluesfortheaxes,theaxeswillautomaticallygrowsoyoucanseeallthedata.

Notethatweusedtheplotcommandtoaddthenextpointtoaplot.ThiscommandmovesthecurrentplotpentothepointthathasanXcoordinateequalto1greaterthanthepreviouslyplottedXcoordinateandaYcoordinateequaltothevaluegivenintheplotcommand(inthefirstcase,thenumberofturtles,andinthesecondcase,thenumberofgreenpatches).Asthepensmovetheyeachdrawaline.

Setupandrunthemodelagain.

Youcannowwatchtheplotbeingdrawnasthemodelisrunning.Yourplotshouldhavethegeneralshapeoftheonebelow,thoughyourplotmightnotlookexactlythesame.

Rememberthatweleft"AutoScale?"on.Thisallowstheplottoreadjustitselfwhenitrunsoutofroom.

Ifyouforgetwhichpeniswhich,youcanedittheplotandcheckthe"Showlegend?"checkbox.

Youmighttryrunningthemodelseveraltimestoseewhataspectsoftheplotarethesameandwhicharedifferentfromruntorun.

Tickcounter

Tomakecomparisonsbetweenplotsfromonemodelrunandanother,itisoftenusefultodothecomparisonforthesamelengthofmodelrun.Learninghowtostoporstartanactionataspecifictimecanhelpmakethishappenbystoppingthemodelatthesamepointeachmodelrun.Keepingtrackofhowmanytimesthegoprocedureisrunisausefulwaytocuetheseactions.That'swhatthetickcounterdoes.

You'realreadyusingthetickcounterinyourmodel,withthereset-ticksandtickcommands,whichalsotriggerplotting.

Youcanalsousethetickcounterforotherthings,suchastosetalimitonthetotallengthofarun.

Changethegoprocedure:

to go if ticks >= 500 [ stop ] move-turtles eat-grass check-death reproduce regrow-grass tickend

Nowsetupandrunthemodel.

Thegraphandmodelwon'tkeeprunningforever.TheyshouldstopautomaticallywhenthetickcounterintheInterfacetab'stoolbarreaches500.

Thetickcommandadvancesthetickcounterby1.ticksisareporterwhichreportsthecurrentvalueofthetickcounter.reset-ticks,inyoursetupprocedure,takescareofrestartingthetickcounterat0whenanewrunissetupandreadytobegin.

Somemoredetails

First,insteadofalwaysusing100turtles,youcanhaveavaryingnumberofturtles.

Createaslidernamed"number":clicktheAddicononthetoolbar,selectSlidernexttoit,andclickonanopenspotintheinterface.Trychangingtheminimumandmaximumvaluesintheslider.Theninsideofsetup-turtles,insteadofcreate-turtles 100youcantype:

to setup-turtles create-turtles number [ setxy random-xcor random-ycor ]end

Testthischangeandcomparehowhavingmoreorfewerturtlesinitiallyaffecttheplotsovertime.

Second,wouldn'titbenicetoadjusttheenergytheturtlesgainandloseastheyeatgrassandreproduce?

Makeaslidercalledenergy-from-grass.Makeanotherslidercalledbirth-energy.Then,insideofeat-grass,makethischange:

to eat-grass ask turtles [ if pcolor = green [ set pcolor black set energy (energy + energy-from-grass) ] ifelse show-energy? [ set label energy ] [ set label "" ] ]end

And,insideofreproduce,makethischange:

to reproduce ask turtles [ if energy > birth-energy [ set energy energy - birth-energy hatch 1 [ set energy birth-energy ] ] ]end

Finally,whatotherslidercouldyouaddtovaryhowoftengrassgrowsback?Arethererulesyoucanaddtothemovementoftheturtlesortothenewlyhatchedturtlesthathappenonlyatcertaintimes?Trywritingthem.

What'snext?

Sonowyouhaveasimplemodelofanecosystem.Patchesgrowgrass.Turtleswander,eatthegrass,reproduce,anddie.

Youhavecreatedaninterfacecontainingbuttons,sliders,switches,monitors,andaplot.You'veevenwrittenaseriesofprocedurestogivetheturtlessomethingtodo.

That'swherethistutorialleavesoff.

Ifyou'dliketolookatsomemoredocumentationaboutNetLogo,theInterfaceGuidesectionofthemanualwalksyouthrougheveryelementoftheNetLogointerfaceinorderandexplainsitsfunction.Foradetaileddescriptionandspecificsaboutwritingprocedures,

refertotheProgrammingGuide.AlloftheprimitivesarelistedanddescribedintheNetLogoDictionary.

Also,youcancontinueexperimentingwithandexpandingthismodelifyou'dlike,experimentingwithdifferentvariablesandbehaviorsfortheagents.

Alternatively,youmaywanttorevisitthefirstmodelinthetutorial,WolfSheepPredation.ThisisthemodelyouusedinTutorial #1.IntheWolfSheepPredationmodel,yousawsheepmovearound,consumeresourcesthatarereplenishedoccasionally(grass),reproduceundercertainconditions,anddieiftheyranoutofresources.Butthatmodelhadanothertypeofcreaturemovingaround--wolves.Theadditionofwolvesrequiressomeadditionalproceduresandsomenewprimitives.Wolvesandsheeparetwodifferent"breeds"ofturtle.Toseehowtousebreeds,studyWolfSheepPredation.

Alternatively,youcanlookatothermodels(includingthemanymodelsintheCodeExamplessectionoftheModelsLibrary)orevengoaheadandbuildyourownmodel.Youdon'tevenhavetomodelanything.Itcanbeinterestingjusttowatchpatchesandturtlesformingpatterns,totrytocreateagametoplay,orwhatever.

Hopefullyyouhavelearnedsomethings,bothintermsoftheNetLogolanguageandabouthowtogoaboutbuildingamodel.Theentiresetofproceduresthatwascreatedaboveisshownbelow.

Appendix:Completecode

ThecompletemodelisalsoavailableinNetLogo'sModelsLibrary,intheCodeExamplessection.It'scalled"Tutorial3".

Noticethatthislistingisfullof"comments",whichbeginwithsemicolons.Commentsletyoumixanexplanationthecoderightinwiththecodeitself.Youmightusecommentstohelpothersunderstandyourmodel,oryoumightusethemasnotestoyourself.

IntheCodetab,commentsaregray,soyoureyescanpickthemouteasily.

turtles-own [energy] ;; for keeping track of when the turtle is ready ;; to reproduce and when it will die

to setup clear-all setup-patches setup-turtles reset-ticksend

to setup-patches ask patches [ set pcolor green ]end

to setup-turtles create-turtles number ;; uses the value of the number slider to create turtles ask turtles [ setxy random-xcor random-ycor ]end

to go if ticks >= 500 [ stop ] ;; stop after 500 ticks move-turtles eat-grass check-death reproduce regrow-grass tick ;; increase the tick counter by 1 each time throughend

to move-turtles ask turtles [ right random 360 forward 1 set energy energy - 1 ;; when the turtle moves it looses one unit of energy ]end

to eat-grass ask turtles [ if pcolor = green [ set pcolor black ;; the value of energy-from-grass slider is added to energy set energy energy + energy-from-grass ] ifelse show-energy? [ set label energy ] ;; the label is set to be the value of the energy [ set label "" ] ;; the label is set to an empty text value ]end

to reproduce ask turtles [ if energy > birth-energy [ set energy energy - birth-energy ;; take away birth-energy to give birth hatch 1 [ set energy birth-energy ] ;; give this birth-energy to the offspring ] ]end

to check-death ask turtles [ if energy <= 0 [ die ] ;; removes the turtle if it has no energy left ]end

to regrow-grass ask patches [ ;; 3 out of 100 times, the patch color is set to green if random 100 < 3 [ set pcolor green ] ]end

InterfaceGuide

ThissectionofthemanualexplainsthefunctionofeachelementinNetLogo'suserinterface.

InNetLogo,youhavethechoiceofviewingmodelsfoundintheModelsLibrary,addingtoexistingmodels,orcreatingyourownmodels.TheNetLogointerfacewasdesignedtomeetalltheseneeds.

Theinterfacecanbedividedintotwomainparts:NetLogomenus,andthemainNetLogowindow.Themainwindowisdividedintotabs.

MenusTabsInternationalusage

Menus

OnaMac,ifyouarerunningtheNetLogoapplication,themenubarislocatedatthetopofthescreen.Onotherplatforms,themenubarisfoundatthetopoftheNetLogowindow.

Thefunctionsavailablefromthemenusinthemenubararelistedinthefollowingchart.

Chart:NetLogomenus

File

New Startsanewmodel.

Open… OpensanyNetLogomodelonyourcomputer.

ModelsLibrary Acollectionofdemonstrationmodels.

RecentFiles Re-opensanypreviouslymodelopenedwith"File->Open"

Save Savethecurrentmodel,orthecurrentlyselectedsourcefile.

SaveAs… Savethecurrentmodel,orthecurrentlyselectedsourcefile,usingadifferentname.

SaveAll Savethecurrentmodelandallopensourcefiles.Thisoptionisonlyavailablewhenoneormoresourcefilesareopen.

UploadtoModelingCommons

UploadsthemodeltoModelingCommons.SeeModelingCommons

SaveAsNetLogo

Savesawebpage,inHTMLformat,containingNetLogowebrunning

NetLogoWeb… yourmodel.

ExportWorld…Savesallvariables,thecurrentstateofallturtlesandpatches,thedrawing,theplots,theoutputareaandtherandomstateinformationtoafile.

ExportPlot… Savesthedatainaplottoafile.

ExportAllPlots… Savesthedatainalltheplotstoafile.

ExportView… Saveapictureofthecurrentview(2Dor3D)toafile(inPNGformat).

ExportInterface… SaveapictureofthecurrentInterfacetab.(inPNGformat)

ExportOutput…

Savethecontentsoftheoutputareaortheoutputsectionofthecommandcentertoafile.

ExportCode… Savethemodel'scodetoanHTMLfile,preservingcolors.

ImportWorld…LoadafilethatwassavedbyExportWorld.

ImportPatchColors… Loadanimageintothepatches;seetheimport-pcolorscommand.

ImportPatchColorsRGB…

LoadanimageintothepatchesusingRGBcolors;seetheimport-pcolors-rgbcommand.

ImportDrawing… Loadanimageintothedrawing,seetheimport-drawingcommand.

ImportHubNetClientInterface…

LoadtheinterfacefromanothermodelintotheHubNetClientEditor.

Print… Sendsthecontentsofthecurrentlyshowingtabtoyourprinter.

Quit ExitsNetLogo.OnaMac,thisitemisontheNetLogomenuinstead.

Edit

Undo Undolasttexteditingactionyouperformed.

Redo Redolastundoactionyouperformed.

Cut Cutsoutorremovestheselectedtextandtemporarilysavesittotheclipboard.

Copy Copiestheselectedtext.

dictionary#import-pcolors

dictionary#import-pcolors-rgb

dictionary#import-drawing

Paste Placestheclipboardtextwherecursoriscurrentlylocated.

Delete Deletesselectedtext.

SelectAll Selectallthetextintheactivewindow.

Find… FindsawordorsequenceofcharacterswithintheInfoorCodetabs.

FindNext FindthenextoccurrenceofthewordorsequenceyoulastusedFindwith.

Comment/Uncomment

UsedintheCodetabtoaddorremovesemicolonsfromcode(semicolonsareusedinNetLogocodetoindicatecomments).

ShiftLeft/ShiftRight UsedintheCodetabtochangetheindentationlevelofcode.

Format UsedintheCodetabtocorrecttheindentationofthecurrentlyselectedcode.

SnaptoGridAvailableonlyintheInterfaceTab.Whenenablednewwidgetsstayona5pixelgridsoitiseasiertolinethemup.(Note:thisfeatureisdisabledwhenzoomedinorout.)

Convertfrom5.3.1to6.0

Availableonlyinan".nls"codetab.Treatsthecodeinthistabasthoughitwerewrittenin5.3.1andconvertsittoruninNetLogo6.Notethatthiswillnottakeintoaccountcodedefinedinthemaincodetab."Undo"doesn'ttakethisoperationintoaccount,soyouwon'twanttosaveunlessyou'resatisfiedwiththechanges.

Tools

Preferences… Opensthepreferencesdialog,whereyoucancustomizevariousNetLogosettings.OnaMac,thisitemisontheNetLogomenuinstead.

Halt

Stopsallrunningcode,includingbuttonsandthecommandcenter.(Warning:sincethecodeisinterruptedinthemiddleofwhateveritwasdoing,youmaygetunexpectedresultsifyoutrytocontinuerunningthemodelwithoutfirstpressing"setup"tostartthemodelrunover.)

GlobalsMonitor Displaysthevaluesofallglobalvariables.

TurtleMonitor

Displaysthevaluesofallofthevariablesinaparticularturtle.Youcancanalsoeditthevaluesoftheturtle'svariablesandissuecommandstotheturtle.(YoucanalsoopenaturtlemonitorviatheView;seetheViewsectionbelow.)

PatchMonitor

Displaysthevaluesofallofthevariablesinaparticularpatch.Youcancanalsoeditthevaluesofthepatch'svariablesandissuecommandstothepatch.(YoucanalsoopenapatchmonitorviatheView;seetheViewsectionbelow.)

LinkMonitor

Displaysthevaluesofallofthevariablesinaparticularlink.Youcancanalsoeditthevaluesofthelink'svariablesandissuecommandstothelink.(YoucanalsoopenalinkmonitorviatheView;seetheViewsectionbelow.)

CloseAllAgentMonitorsClosesallopenagentmonitorwindows.

CloseMonitorsforDeadAgents

Closesallopenagentmonitorwindowstargetingdeadagents.

Hide/ShowCommandCenter

Makesthecommandcentervisibleorinvisible.(Notethatthecommandcentercanalsobeshownorhidden,orresized,withthemouse.)ThisoptionisonlyavailablewhentheInterfaceTabisactive

3DView Opensthe3Dview.SeetheViewssectionformoreinformation.

ColorSwatches

OpenstheColorSwatches.SeetheColorSectionoftheProgrammingGuidefordetails.

TurtleShapesEditor Drawturtleshapes.SeetheShapesEditorGuideformoreinformation.

LinkShapesEditor Drawlinkshapes.SeetheShapesEditorGuideformoreinformation.

BehaviorSpaceRunsthemodeloverandoverwithdifferentsettings.SeetheBehaviorSpaceGuideformoreinformation.

SystemDynamicsModeler

OpenstheSystemDynamicsModeler.SeetheSystemDynamicsModelerGuideformoredetails.

PreviewCommandsEditor

Allowsforeasyeditingofthecommandssequenceusedtocreatepreviewimagesformodels.Givesawaytospecifywhatcodewillbeused(orspecifythattheimageismanuallymade)andpreviewtheresultingimage.

HubNetClientEditor

OpenstheHubNetClientEditor.SeetheHubNetAuthoringGuideformoredetails.

HubNetControlCenter

DisabledifnoHubNetactivityisopen.SeetheHubNetGuideformoreinformation.

Zoom

Larger Increasetheoverallscreensizeofthemodel.Usefulonlargemonitorsorwhenusingaprojectorinfrontofagroup.

NormalSize Resetthescreensizeofthemodeltothenormalsize.

Smaller Decreasetheoverallscreensizeofthemodel.

TabsThismenuofferskeyboardshortcutsforeachofthetabs.OnaMac,it'sCommand1throughCommand3.OnWindows,it'sControl1throughControl3.Additionalnumbersareusedfortabscontaining".nls"files.

Help

LookUpInDictionary

Opensabrowserwiththedictionaryentryfortheselectedcommandorreporter.(YoumayalsousetheF1keyforthis.)

NetLogoUserManual Opensthismanualinawebbrowser.

NetLogoDictionary OpenstheNetLogoDictionaryinawebbrowser.

NetLogoUsersGroup OpenstheNetLogoUsersGroupsiteinawebbrowser.

IntroductiontoAgent-BasedModeling

OpenstheMITPresspagefor"IntroductiontoAgent-BasedModeling"(byUriWilenskyandWilliamRand)inawebbrowser.

Donate OpenstheNetLogodonationpageinawebbrowser.

AboutNetLogo6.0.2…

InformationonthecurrentNetLogoversionyouarerunning.OnaMac,thismenuitemisontheNetLogomenuinstead.

Tabs

AtthetopofNetLogo'smainwindowarethreetabslabeled"Interface","Info"and"Code".Onlyonetabatatimecanbevisible,butyoucanswitchbetweenthembyclickingonthetabsatthetopofthewindow.

Rightbelowtherowoftabsisatoolbarcontainingarowofcontrols.Thecontrolsavailablevaryfromtabtotab.

InternationalUsage

Charactersets

NetLogoalwayssavesandloadsmodelsintheUTF-8characterencoding,whichincludesawiderangeofinternationalcharacters.

IfyouareinalocaleotherthanU.S.English,letusknowifyouhaveanytroubleusingyourlocal

characterset.

TheTransitionGuidehasadviceonconvertingmodelscontaininginternationalcharactersfromearlierNetLogoversions.

Languages

MostofNetLogo'sGUI,andsomeofitserrormessages,arenow"internationalized".ThismeansthatitisnowpossibletodisplayNetLogoindifferentlanguages.

Wesay"possible"herebecausethecurrentreleaseofNetLogoonlysupportsEnglish,Spanish,Chinese,Russian,andJapanese.

Theworkoninternationalizationisnotcomplete.Weareaskingforhelpfromtheusercommunityinhelpinguslocalizeitemssuchasthemenusanderrormessages.

Defaultlanguage

Bydefault,NetLogousesthesamelanguageyouroperatingsystemissetto,ifavailable.(Ifunavailable,yougetEnglish.)

Youcanrecordapreferenceforadifferentlanguagebychangingthe"UserInterfaceLanguage"optioninthepreferencesdialog.OnceanewlanguageischosenyouwillhavetorestartNetLogo.

Supportfortranslators

WehopeNetLogowillbecomeavailableinmanydifferentlanguages.IfyouwouldliketotranslateNetLogotoyourlanguage,seethiswikipageforinstructions.

https://github.com/NetLogo/NetLogo/wiki/Localization

InterfaceTabGuide

TheInterfacetabiswhereyouwatchyourmodelrun.Italsohastoolsyoucanusetoinspectandalterwhat'sgoingoninsidethemodel.

WhenyoufirstopenNetLogo,theInterfacetabisemptyexceptfortheview,wheretheturtlesandpatchesappear,andtheCommandCenter,whichallowsyoutoissueNetLogocommands.

WorkingwithinterfaceelementsThe2Dand3DviewsCommandCenterPlotsSlidersAgentmonitors

Workingwithinterfaceelements

ThetoolbarontheInterfacetabcontainsbuttonsthatletyouedit,delete,andcreateitemsintheInterfacetabandamenuthatletsyouselectdifferentinterfaceitems(suchasbuttonsandsliders).

Thebuttonsinthetoolbararedescribedbelow.

Adding:Toaddaninterfaceelement,selecttheelementfromthedropdownmenu.NotethattheAddbuttonstaysdown.Thenclickonthewhiteareabelowthetoolbar.(Ifthemenuisalreadyshowingtherighttype,youcanjustpresstheAddbuttoninsteadofusingthemenuagain.)

Selecting:Toselectaninterfaceelement,dragarectanglearounditwithyourmouse.Agrayborderwithblackhandleswillappeararoundtheelementtoshowitisselected.

Selectingmultipleitems:Youcanselectmultipleinterfaceelementsatthesametimebyincludingthemintherectangleyoudrag.Ifmultipleelementsareselected,oneofthemisthe"key"item,whichmeansthatifyouusethe"Edit"or"Delete"buttonsontheInterfaceToolbar,onlythekeyitemisaffected.Thekeyitem'sborderisdarkergray.

Unselecting:Tounselectallinterfaceelements,clickthemouseonthewhitebackgroundoftheInterfacetab.Tounselectanindividualelement,right-clicktheelementandchoose"Unselect"fromthepopupmenu.

Editing:Tochangethecharacteristicsofaninterfaceelement,selecttheelement,thenpressthe"Edit"buttonontheInterfacetoolbar.Youmayalsodoubleclicktheelementonceitisselected.Athirdwaytoeditanelementistoright-clickitandchoose"Edit"fromthepopupmenu.Ifyouusethislastmethod,itisnotnecessarytoselecttheelementfirst.

Moving:Selecttheinterfaceelement,thendragitwithyourmousetoitsnewlocation.Ifyouholddowntheshiftkeywhiledragging,theelementwillmoveonlystraightupanddownorstraightleftandright.

Resizing:Selecttheinterfaceelement,thendragtheblack"handles"intheselectionborder.

Deleting:Selecttheelementorelementsyouwanttodelete,thenpressthe"Delete"buttononthe

Interfacetoolbar.Youmayalsodeleteanelementbyright-clickingitandchoosing"Delete"fromthepopupmenu.Ifyouusethislattermethod,itisnotnecessarytoselecttheelementfirst.

Tolearnmoreaboutthedifferentkindsofinterfaceelements,refertothechartbelow.

Chart:InterfaceToolbar

Icon&Name DescriptionAbuttoniseitheronceorforever.Whenyouclickonaoncebutton,itexecutesitsinstructionsonce.Theforeverbuttonexecutestheinstructionsoverandover,untilyouclickonthebuttonagaintostoptheaction.Ifyouhaveassignedanactionkeytothebutton,pressingthecorrespondingkeyboardkeywillactjustlikeabuttonpresswhenthebuttonisinfocus.Buttonswithactionkeyshavealetterintheupperrightcornerofthebuttontoshowwhattheactionkeyis.IfthekeyboardfocusisinanotherinterfaceelementsuchastheCommandCenter,pressingtheactionkeywon'ttriggerthebutton.Theletterintheupperrighthandcornerofthebuttonwillbedimmedinthissituation.Toenableactionkeys,clickinthewhitebackgroundoftheInterfacetab.

Slidersareglobalvariables,whichareaccessiblebyallagents.Theyareusedinmodelsasaquickwaytochangeavariablewithouthavingtorecodetheprocedureeverytime.Instead,theusermovestheslidertoavalueandobserveswhathappensinthemodel.

Switchesareavisualrepresentationforatrue/falseglobalvariable.Youmaysetthevariabletoeitheron(true)oroff(false)byflippingtheswitch.

Choosersletyouchooseavalueforaglobalvariablefromalistofchoices,presentedinadropdownmenu.Thechoicesmaybestrings,numbers,booleans,orlists.

InputBoxesareglobalvariablesthatcontainstringsornumbers.Themodelauthorchooseswhattypesofvaluesyoucanenter.Inputboxescanbesettocheckthesyntaxofastringforcommandsorreporters.Numberinputboxesreadanytypeofconstantnumberreporterwhichallowsamoreopenwaytoexpressnumbersthanaslider.ColorinputboxesofferaNetLogocolorchooser.

Monitorsdisplaythevalueofanyreporter.Thereportercouldbeavariable,acomplexreporter,oracalltoareporterprocedure.Monitorsautomaticallyupdateseveraltimespersecond.

Plotsshowdatathemodelisgenerating.

Theoutputareaisascrollingareaoftextwhichcanbeusedtocreatealogofactivityinthemodel.Amodelmayonlyhaveoneoutputarea.

NotesletsyouaddinformativetextlabelstotheInterfacetab.Thecontentsofnotesdonotchangeasthemodelruns.

TheothercontrolsintheInterfacetoolbarallowyoutocontroltheviewupdatesandvariousothermodelproperties.

Thesliderletsyoucontrolhowfastthemodelruns.Slowercanbevaluablesincesomemodelsrunsofastthey'rehardtofollow.Youcanalsofast-forwardthemodelbymovingtheslidertotheright,reducingthefrequencyofviewupdates.Theviewupdatescheckboxcontrolswhetherviewupdateshappenatall.Theupdatemodemenuallowsyoutoswitchbetweencontinuousandtick-basedupdates.The"Settings..."buttonallowsyoutochangemodelsettings.

"Continuous"updatesmeansthatNetLogoupdates(thatis,redraws)theviewmanytimesasecond,

regardlessofwhatisgoingoninthemodel."Tick-based"updatesmeansthattheviewonlyupdateswhenthetickcounteradvances.(Forafullerdiscussionofviewupdates,seetheProgrammingGuide.)

The2Dand3Dviews

ThelargeblacksquareintheInterfacetabisthe2Dview.It'savisualrepresentationoftheNetLogoworldofturtlesandpatches.Initiallyit'sallblackbecausethepatchesareblackandtherearenoturtlesyet.Youcanopenthe3DView,analternatevisualrepresentationoftheworld,byrightclicking(ctrl-clickingonMac)ontheViewandchoosing"Switchto3DView"(thisoptionisalsoavailableinthe"Tools"menu).

ThereareanumberofsettingsfortheView(accessiblebyeditingtheView,orbypressingthe"Settings..."buttonintheInterfaceToolbar):

Noticethatthesettingsarebrokenupintothreegroups.Thereareworld,view,andtickscountersettings.Worldsettingsaffectthepropertiesoftheworldthattheturtleslivein(changingthemmayrequireresettingtheworld).Viewandtickcountersettingsonlyaffecttheappearance,changingthemwillnotaffecttheoutcomeofthemodel.

Theworldsettingsallowyoutodefinetheboundariesandtopologyoftheworld.Atthetopoftheleftsideoftheworldpanelyoucanchoosealocationfortheoriginoftheworldeither"Center","Corner","Edge",or"Custom".Bydefaulttheworldhasacenterconfigurationwhere(0,0)isatthecenteroftheworldandyoudefinethenumberofpatchesfromthecentertotherightandleftboundariesandthenumberofpatchesfromthecentertothetopandbottomboundaries.Forexample:ifyousetMax-Pxcor=10,thenMin-Pxcorwillautomaticallybesetto-10,thusthereare10patchestotheleftoftheoriginand10patchestotherightofpatch00,foratotalof21patchesineachrow.

ACornerconfigurationallowsyoutodefinethelocationoftheoriginasoneofthecornersoftheworld,upperleft,upperright,lowerleft,orlowerright.Thenyoudefinethefarboundaryinthexandydirections.Forexampleifyouchoosetoputtheorigininthelowerleftcorneroftheworldyoudefinetherightandtop(positive)boundaries.

Edgemodeallowsyoutoplacetheoriginalongoneoftheedges(xory)thendefinethefarboundaryinthatdirectionandbothboundariesintheother.Forexampleifyouselectedgemodealongthebottomoftheworld,youmustalsodefinethetopboundary,aswellastheleftandtheright.

Finally,Custommodeallowsyoutoplacetheoriginatanylocationintheworld,thoughpatch00muststillexistintheworld.

Asyouchangethesettingsyouwillnoticethatthechangesyoumakearereflectedinthepreviewontherightsideofthepanelwhichshowstheoriginandtheboundaries.Thewidthandheightoftheworldaredisplayedbelowthepreview.

Alsobelowthepreviewtherearetwocheckboxes,theworldwrapsettings.Theseallowyoutocontrolthetopologyoftheworld.Noticewhenyouclickthecheckboxesthepreviewindicateswhichdirectionsallowwrapping,andthenameofthetopologyisdisplayednexttotheworlddimensions.SeetheTopologysectionoftheProgrammingGuideformoreinformation.

Theviewsettingsallowyoutocustomizethelookoftheviewwithoutchangingtheworld.Changingviewsettingswillneverforceaworldreset.Tochangethesizeofthe2DViewadjustthe"PatchSize"setting,measuredinpixels.Thisdoesnotchangethenumberofpatches,onlyhowlargethepatchesappearinthe2DView.(Notethatthepatchsizedoesnotaffectthe3DView,asyoucansimplymakethe3DViewlargerbymakingthewindowlarger.)

Thefontsizesettingletsyoucontrolthesizeofturtle,patch,andlinklabels.

Theframeratecontrolshowoftentheviewgetsupdated.Thiscanhaveadramaticeffectonthedefaultspeedatwhichamodelruns.Formoredetails,seetheviewupdatessectionoftheProgrammingGuide.

The"Smoothedges"checkboxcontrolstheuseofanti-aliasinginthe3Dviewonlyandonlyappearswheneditingfromthe3Dview.Uncheckingitmakeslinesappearmorejaggedbutmayspeeduprendering.

Tickcountersettingscontroltheappearanceofthetickcounterwhichisvisible(ornot)intheviewcontrolstrip.

Turtle,patchandlinkmonitorsareeasilyavailablethroughtheView,justright-clickontheturtleorpatchyouwanttoinspect,andchoose"inspectturtle..."or"inspectpatch..."fromthepopupmenu.Youcanalsowatch,followorrideaturtlebyselectingtheappropriateitemintheturtlesub-menu.(Turtle,patchandlinkmonitorscanalsobeopenedfromtheToolsmenuorbyusingtheinspectcommand.)

SomeNetLogomodelsletyouinteractwiththeturtlesandpatcheswithyourmousebyclickinganddraggingintheView.

Manipulatingthe3DView

Atthebottomofthewindowtherearebuttonstomovetheobserver,orchangetheperspectivefromwhichyouarelookingattheworld.

Abluecrossappearsatthecurrentfocuspointasyouadjustthesesettings.Thelittlebluetrianglewillalwayspointalongthey-axisinthepositivedirection,soyoucanorientyourselfincaseyougetlost.

Tolookattheworldfromadifferentangle,pressthe"rotate"button,thenclickanddragthemouse.Theobserverwillcontinuetofacethesamepointasbefore(wherethebluecrossis)butitspositionintherelationtothexy-planewillchange.

Tomovecloserorfartherawayfromtheworldortheagentyouarewatching,followingorriding,pressthe"zoom"buttonanddragupanddown.Notewhenyouareinfolloworridemodezoomingwillswitchyoubetweenrideandfollow,sincerideisjustaspecialcaseoffollowwherethedistanceatwhichyouarefollowingis0.

Tochangethepositionoftheobserverwithoutchangingthedirectionitisfacingselectthe"move"buttonanddragthemouseinsidethe3DViewwhileholdingdownthemousebutton.

Toallowthemousepositionandstatetobepassedtothemodelselectthe"interact"buttonanditwillfunctionjustasthemousedoesinthe2Dview.

Toreturntheobserverandfocuspointtotheirdefaultpositionspressthe"ResetPerspective"button(orusethereset-perspectivecommand).

FullscreenMode

Toenterfullscreenmode,pressthe"FullScreen"button,toexitfullscreenmode,presstheEsckey.

Note:Fullscreenmodedoesn'tworkoneverycomputer.Itdependsonyourgraphicscard.SeetheSystemRequirementsfordetails.

3DShapes

Someshapesareautomaticallymappedtotrue3Dcounterpartsinthe3Dview.Forexample,the2Dcircleshapebecomesasphereinthe3Dview.Shapename 3Dshapedefault 3Dturtleshapecircle spheredot smallspheresquare cubetriangle coneline 3Dlinecylinder 3Dcylinderline-half 3Dline-halfcar 3Dcar

Allothershapesarebasedontheir2Dforms.Ifashapeisarotatableshape,itisassumedtobeatopviewanditisextrudedasifthroughacookiecutterandorientedparalleltothexy-plane,asinAnts.

Or,ifashapeisnon-rotatable,itisassumedtobeasideview,anditisdrawnalwaysfacingtheobserver,asinWolfSheepPredation.

CommandCenter

TheCommandCenterallowsyoutoissuecommandsdirectly,withoutaddingthemtothemodel'sprocedures.Thisisusefulforinspectingandmanipulatingagentsonthefly.

(Tutorial#2:CommandsisanintroductiontousingcommandsintheCommandCenter.)

Let'stakealookatthedesignoftheCommandCenter.

Thesmallerbox,belowthelargebox,iswhereyoutypeacommand.AftertypingitpresstheReturnorEnterkeytorunit.

Totheleftofwhereyoutypeisapopupmenuthatinitiallysays"observer>".Youcanchooseeitherobserver,turtles,orpatches,tospecifywhichagentsrunthecommandyoutype.

Tip:aquickerwaytochangeagenttypesistousetheTabkey.

Reporters

IfyouenterareporterintotheCommandCenter,theshowcommandwillbeinsertedbeforeitautomatically.

Accessingpreviouscommands

Afteryoutypeacommand,itappearsinthelargescrollingboxabovethecommandline.YoucanuseCopyontheEditmenuinthisareatocopycommandsandthenpastethemelsewhere,suchastheCodetab.

Youcanalsoaccesspreviouscommandsusingthehistorypopup,whichisthesmalldownwardpointingtriangletotherightofwhereyoutypecommands.Clickonthetriangleandamenuofpreviouslytypedcommandsappears,soyoucanpickonetouseagain.

Tip:aquickerwaytoaccesspreviouscommandsiswiththeupanddownarrowkeysonyourkeyboard.

Clearing

Toclearthelargescrollingareacontainingpreviouscommandsandoutput,click"clear"inthetoprightcorner.

Toclearthehistorypopupmenu,choose"ClearHistory"onthatmenu.

Arranging

YoucanhideandshowthecommandcenterusingtheHideCommandCenterandShowCommandCenteritemsontheToolsmenu.

Toresizethecommandcenter,dragthebarthatseparatesitfromthemodelinterface.Or,clickoneofthelittlearrowsontherightendofthebartomakethecommandcentereitherverybigorhiddenaltogether.

Toswitchbetweenaverticalcommandcenterandahorizontalone,clickthebuttonwiththedouble-headedarrow,justtotheleftof"Clear".

Plots

Whenthemousepointerisoverthewhiteareaofaplot,thexandycoordinatesofthemouselocationappear.(Notethatthemouselocationmightnotcorrespondexactlytoanyactualdatapointsintheplot.Ifyouneedtoknowtheexactcoordinatesofplottedpoints,usetheExportPlotmenuitemandinspecttheresultingfileinanotherprogram.)

Whenyoucreateaplot,aswithallwidgets,theeditdialogautomaticallyappears.

Manyofthefieldsarefairlyself-explanatory,suchasthenameoftheplot,labelsforthexandyaxes,rangesfortheaxes,andthe"Showlegend?"checkbox.

IfAutoScale?ischeckedthexandychangeswillautomaticallyreadjustaspointsareaddedtotheplotiftheyareoutsidethecurrentrange.

Under"Plotsetupcommands"and"Plotupdatecommands"youcanentercommandsthatwillautomaticallyberunatappropriatetimes.Clickthelittletriangletoopenthetextboxforthecommands.PlotcommandsareexplainedinmoredetailinthePlottingsectionoftheProgrammingGuide.

PlotPens

Intheplotpenssectionofthedialog,youcancreateandcustomizeyourplot'spens.Eachtablerowrepresentsapen.Bydefaultthereisonepennamed"default".(Youmaywishtochangeittoanamethathasmeaninginyourmodel.)

Toeditthecolorofapenclickthecoloredrectangletotheleftofthepen'sname.ThiswillbringupadialogthatallowsyoutosetthecolortooneoftheNetLogobasehuesoracustomcolorusingthecolorswatches.

Toeditthepen'sname,doubleclickthename.

Inthe"PenUpdateCommands"columnyoucanentercommandsthatwillberunwhenreset-ticks,tick,orupdate-plotscommandsarerun.ThisisexplainedinmoredetailinthePlottingsectionoftheProgrammingGuide.

Thelastcolumnhastwobuttons.Clickingthepenciliconwillbringupaneditdialogwithadditionalpensettings.Thetrashcanbuttondeletesthepen.

PlotPenAdvancedSettings

Clickingapen'seditbuttonwillopenthisdialog:

Modeallowsyoutochangetheappearanceoftheplotpen:line,bar(forabarchart),orpoint(ascatterplotofindividualpoints).Intervalistheamountbywhichxadvanceseverytimeyouusetheplotcommand.Ifthe"Showinlegend"checkboxischeckedtheselectedpenwillbeapartofthelegendintheupperrighthandcorneroftheplot.Inthe"Setupcommands"fieldyoucanentercommandsthatwillberunwhenreset-ticksorsetup-plotsruns.Inthe"Updatecommands"fieldyoucanentercommandsthatwillberunwhentickorupdate-plotsruns.Thisfieldreappearsintheadvanceddialogtoprovidespaceforeditinglengthiersetsofcommands.

FormoredetailedinformationonhoweachofthesefeaturesworksyoucanseethePlottingSectionoftheProgrammingGuide.

Sliders

Asliderhasanassociatedglobalvariable.Movingthesliderchangesthevariable'svalue.

WhenyouplaceasliderintheInterfacetabtheeditdialogautomaticallyopens,aswithallwidgets.Mostofthefieldswillbefamiliar.However,itisimportanttonoticetheminimum,maximumandincrementfieldswilltakeanyreporter,notjustconstants.So,forexample,youcouldmaketheminimummin-pxcorandthemaximummax-pxcorandthesliderboundswillautomaticallyadjustwhenyouchangethesizeoftheworld.

AgentMonitors

Agentmonitorsdisplayboththevaluesofallthevariablesforaparticularagentandamini-viewthat

showstheagentandasmallareaaroundit.

YoucanopenagentmonitorsthroughtheToolsmenuortheinspectcommand.

Youcanzoominoroutusingthesliderbeneaththeviewandyoucanwatchtheagentinthemainviewusingthewatch-mebutton.

Belowthesliderthecurrentvalueofeachagentvariableisdisplayed.Youcanenteranewvalue.Itwillbeasif,forexample,thecodeset pcolor ...hadrun.

Belowtheagentvariableareathereisamini-commandcenter.Ratherthanrunningcodeastheobserver,ortalkingtoalloftheturtles,patches,orlinks,thecodeenteredinthiscommandcenterisrunonlybythisagent.

Youcancloseanagentmonitorbyclickingtheboxintheupperleftcorner,orbypressingtheEsckey.Ifyouholddownshiftwhileyouclicktheboxallopenagentmonitorswillcloseoryoucanclosealltheagentmonitorsusingthe"CloseAllMonitors"optionintheToolsMenu.

InfoTab

TheInfotabprovidesanintroductiontoamodel.Itexplainswhatsystemisbeingmodeled,howthemodelwascreated,andandhowtouseit.Itmayalsosuggestthingstoexploreandwaystoextendthemodel,orcallyourattentiontoparticularNetLogofeaturesthemodeluses.

YoumaywishtoreadtheInfotabbeforestartingamodel.

Editing

Thenormal,formattedviewoftheInfotabisnoteditable.Tomakeedits,clickthe"Edit"button.Whendoneediting,clickthe"Edit"buttonagain.

YouedittheInfotabasunformattedplaintext.Whenyou'redoneediting,theplaintextyouenteredisdisplayedinamoreattractiveformat.

Tocontrolhowtheformatteddisplaylooks,youusea"markuplanguage"calledMarkdown.YoumayhaveencounteredMarkdownelsewhere;itisusedonanumberofwebsites.(Thereareothermarkuplanguagesinuseontheweb;forexample,WikipediausedamarkuplanguagecalledMediaWiki.Markuplanguagesdifferindetails.)

TheremainderofthisguideisatourofMarkdown.

HeadingsParagraphsItalicizedandboldtextOrderedlistsUnorderedlistsLinksImagesBlockquotationsCodeCodeblocksSuperscriptsandsubscriptsNotesonusageOtherfeatures

Headings

Aheadingbeginswithoneormorehashmarks(#).Firstlevelheadingsgetonehash,secondlevelheadingsgettwo,andsoonuptofourlevels.

Input

# First-level heading

## Second-level heading

### Third-level heading

#### Fourth-level heading

Paragraphs

Example

This is a paragraph. There are no spaces before the word 'This'.

This is another paragraph. The first line has two sentences.The entire paragraph has two lines and three sentences.

Line breaks in the input,Make line breaks in the output,Like this.

Formatted

Thisisaparagraph.Therearenospacesbeforetheword'This'.

Thisisanotherparagraph.Thefirstlinehastwosentences.Theentireparagraphhastwolinesandthreesentences.

Linebreaksintheinput,Makelinebreaksintheoutput,Likethis.

Italicizedandboldtext

Example

For italics, surround text with underscores:_hello, world_.

For bold, surround text with two asterisks:**hello, world**.

You can also combine them:_**hello**_ and **_goodbye_**

Formatted

Foritalics,surroundtextwithunderscores:hello,world.

Forbold,surroundtextwithtwoasterisks:hello,world.

Youcanalsocombinethem:helloandgoodbye

Orderedlists

Example

We are about to start an ordered list.

1. Ordered lists are indented 2 spaces. 1. Subitems are indented 2 more spaces (4 in all). 2. The next item in the list starts with the next number. 3. And so on...

Formatted

Weareabouttostartanorderedlist.

1. Orderedlistsareindented2spaces.1. Subitemsareindented2morespaces(4inallforasecondlevelitem).

2. Thenextitemintheliststartswiththenextnumber.3. Andsoon…

Unorderedlists

Example

We are about to start an unordered list.

* Like ordered lists, unordered lists are also indented 2 spaces. * Unlike ordered lists, unordered lists use stars instead of numbers. * Sub items are indented 2 more spaces. * Here's another sub item.

Formatted

Weareabouttostartanunorderedlist.

Likeorderedlists,unorderedlistsarealsoindented2spaces.Unlikeorderedlists,unorderedlistsusestarsinsteadofnumbers.

Subitemsareindented2morespaces.Here'sanothersubitem.

Links

Automaticlinks

Thesimplestwaytocreatealinkistojusttypeitin:

Example


Formatted


Linkswithtext

Ifyouwanttouseyourowntextforthelink,here'show:

[link text here](link.address.here)

Example

[NetLogo](http://ccl.northwestern.edu/netlogo/)


Formatted

NetLogo

Locallinks

Itisalsopossibletolinktoapageonyourcomputer,insteadofapagesomewhereontheInternet.

Locallinkshavethisform:

[alt text](file:path)

Anyspacesinthepathmustbeconvertedto%20.Forexample,this:

file:my page.html

mustbewrittenas:

file:my%20page.html

Thepathisrelativetothedirectorythatthemodelfileisin.

Example

Theeasiestwaytolinktofilesonyourcomputeristoputthemintothesamedirectoryasyourmodel.Assumingyouhaveafilenamedindex.htmlinthesamedirectoryasyourmodel,thelinkwouldlooklikethis:

[Home](file:index.html)

Example

Hereisanotherexamplewherethefilelivesinadirectorycalleddocs,anddocsisinthesamedirectoryasyourmodel:

[Home](file:docs/index.html)

Images

Imagesareverysimilartolinks,buthaveanexclamationpointinfront:

![alt text](http://location/of/image)

(Thealternatetextisthetextthatgetsdisplayediftheimageisnotfound.)

Example

![NetLogo](http://ccl.northwestern.edu/netlogo/images/netlogo-title-new.jpg)


Formatted

Localimages

Alsoverysimilartolinks,itispossibletodisplayanimageonyourcomputerinsteadofanimagesomewhereontheInternet.Assumingyouhaveanimagenamedimage.jpg,localimageslooklikethis:

![alt text](file:path)

Thepathisrelativetothedirectorythatthemodelfileisin.

Aswithlocallinks,anyspacesinthenameofthefileorthepathmustbeconvertedto%20.

Example

Likelocallinks,theeasiestwaytodisplayimagesonyourcomputeristoputthemintothesamedirectoryasyourmodel.Thisexampledisplaystheimage"PerspectiveExample.png",whichresidesinthesamedirectoryasthismodel(InfoTabExample).

![Example](file:Perspective%20Example.png)

Formatted

Blockquotations

Consecutivelinesstartingwith>willbecomeblockquotations.Youcanputwhatevertextyoulikeinsideofitandyoucanalsostyleit.

Example

> Let me see: four times five is twelve, and four times six is thirteen,> and four times seven is --- _oh dear!_> I shall never get to twenty at that rate!

Formatted

Letmesee:fourtimesfiveistwelve,andfourtimessixisthirteen,andfourtimessevenis--ohdear!Ishallnevergettotwentyatthatrate!

Code

Toincludeashortpieceofcodeinasentence,surrounditwithbackticks(`).

Example

You can create a single turtle with the `crt 1` command.

Formatted

Youcancreateasingleturtlewiththecrt 1command.

Codeblocks

Itisalsopossibletohaveblocksofcode.Tocreateacodeblock,indenteverylineoftheblockby4spaces.Anotherwayistosurrounditwithathreebacktickslinebeforeandaftertheblock.(Ifyoudon'twantyourcodetobecoloredasNetLogocode,addtextafterthefirstthreebackticks.)

Example

About to start the code block.Leave a blank line after this one, and then put the code block:

; a typical go procedure to go ask turtles [ fd 1 ] tick end

or:

About to start the code block.Leave a blank line after this one, and then put the code block:

```; a typical go procedureto go ask turtles [ fd 1 ] tickend```

Formatted

Abouttostartthecodeblock.Leaveablanklineafterthisone,andthenputthecodeblock:

; a typical go procedureto go ask turtles [ fd 1 ] tickend

Superscriptsandsubscripts

Superscriptsandsubscriptsareusefulforwritingformulas,equations,footnotesandmore.Subscriptsappearhalfacharacterbelowthebaseline,andarewrittenusingtheHTMLtag.Superscriptsappearhalfacharacterabovethebaseline,andarewrittenusingtheHTMLtag.

Example

H2O

2x4 + x2

WWW[1]

Formatted

H2O

2x4+x2+42

WWW[1]

Notesonusage

Paragraphs,lists,codeblocksandotherfeaturesshouldbeseparatedfromeachotherwithablankline.Ifyoufindthatsomethingisn'tformattedthewayyouexpected,itmightbebecauseyouneedtoaddablanklinebeforeit.

Topreventaspecialcharacterfrombeingtreatedasmarkup,putabackslash(\)beforeit.

WeuseGitHubflavorednewlines(https://github.github.com/github-flavored-markdown/)insteadoftraditionalMarkdownhandlingofnewlines.Thismeansthatnewlinesaretreatedasreallinebreaks,insteadofbeingcombinedwiththepreviouslineintoasingleparagraph.

Otherfeatures

Markdownhasadditionalfeaturesthatwehavenotshownhere.

Wehavetestedthefeaturesshownaboveonavarietyofsystems.IfyouuseotherMarkdownfeatures,youmayfindthattheyworkonyourcomputer,ornot.Evenafeaturethatworksonyourcomputermightworkdifferently,ornotworkatall,forsomeonewithadifferentoperatingsystemorJavavirtualmachine.

IfyouwantallNetLogouserstobeabletoreadyourInfotab,useonlythefeaturesshownabove.

MoreinformationaboutMarkdownisathttp://daringfireball.net/projects/markdown/.ForrenderingMarkdown,NetLogousestheFlexmark-javalibrary.

https://github.github.com/github-flavored-markdown/

http://daringfireball.net/projects/markdown/

https://github.com/vsch/flexmark-java

CodeTabGuide

TheCodetabiswherethecodeforthemodelisstored.CommandsyouonlywanttouseimmediatelygointheCommandCenter;commandsyouwanttosaveanduselater,overandoveragain,arefoundintheCodetab.

Todetermineifthecodehasanyerrors,youmaypressthe"Check"button.Ifthereareanysyntaxerrors,theCodetabwillturnred,thecodethatcontainstheerrorwillbehighlighted,andanerrormessagewillappear.

Switchingtabsalsocausesthecodetobechecked,soifyoujustswitchtabs,pressingtheCheckbuttonfirstisn'tnecessary.

Tofindafragmentofcodeintheprocedures,clickonthe"Find"buttonintheCodetoolbarandtheFinddialogwillappear.

Youmayenterawordorphrasetofind,andoptionallyalsoanewwordorphrasetoreplaceitwith.The"Ignorecase"checkboxcontrolswhetherthecapitalizationmustbethesametoindicateamatch.

Ifthe"Wraparound"checkboxischecked,theentireCodetabwillbecheckedforthephrase,startingatthecursorposition.Whenitreachestheenditwillreturntothetop,otherwiseonlytheareafromthecursorpositiontotheendoftheCodetabwillbesearched.The"Next"and"Previous"buttonswillmovedownanduptofindanotheroccurrenceofthesearchphrase.

"Replace"changesthecurrentlyselectedphrasewiththereplacephraseand"Replace&Find"changestheselectedphraseandmovestothenextoccurrence."ReplaceAll"willchangeallinstancesofthefindphraseinthesearchareawiththereplacephrase.

Tofindaparticularproceduredefinitioninyourcode,usethe"Procedures"popupmenuintheCodetab.Themenulistsallproceduresinalphabeticalorder.

The"ShiftLeft","ShiftRight","Comment",and"Uncomment"itemsontheEditmenuareusedintheCodetabtochangetheindentationlevelofyourcodeoraddandremovesemicolons,whichmarkcomments,fromsectionsofcode.

Formoreinformationaboutwritingprocedures,readTutorial#3:ProceduresandtheProgrammingGuide.

IncludedFilesMenu

Caution:Theincludesfacilityisnewandexperimental.

Whenyouaddthe__includeskeywordtoamodelamenutotherightoftheproceduresmenuappears.Thisisthe"IncludedFiles"menuwhichlistsalltheNetLogosourcefiles(.nls)includedinthisfile.YoucanmakethismenualwaysvisibleusingthePreferencesdialog.

Youcanchooseafilenamefromthemenutoopenatabforthatfile,oryoucanopenaneworexistingfileusingNewSourceFileandOpenSourceFile,respectively.

Onceyou'veopenednewtabstheybecomeaccessiblefromtheTabsmenu,andyoucanusethekeyboardtomovefromtabtotab(Command+numberonMac,Control+numberonotheroperatingsystems).

Automaticindentation

WhentheIndentAutomaticallycheckboxisselected,NetLogowillautomaticallyattempttoalignyourcodeinalogicallystructuredformat.Forexample,whenyouopenasetofsquarebrackets"["(perhapsafteranifstatement),NetLogowillautomaticallyaddspacessothatthefollowinglinesofcodearetwospacesfurtherindentedthanthebracket.Whenyouclosethesquarebracketstheclosingbracketwillbelinedupwiththematchingopenbracket.

NetLogowilltrytoindentthecodeasyoutype,butyoucanalsopressthetabkeyanywhereonanylinetoaskNetLogotoindentthelineimmediately.Or,youcanselectawholeregionofcodeandpressthetabkeytore-indentallofit.

ProgrammingGuide

ThissectiondescribestheNetLogoprogramminglanguageindetail.

TheCodeExamplemodelsmentionedthroughoutcanbefoundintheCodeExamplessectionoftheModelsLibrary.

AgentsProceduresVariablesTickcounterColorsAskAgentsetsBreedsButtonsListsMathRandomnumbersTurtleshapesLinkshapesViewupdatesPlottingStringsOutputFileI/OMoviesPerspectiveDrawingTopologyLinksAnonymousproceduresAsk-ConcurrentUserInteractionPrimitivesTieMultiplesourcefilesSyntax

Agents

TheNetLogoworldismadeupofagents.Agentsarebeingsthatcanfollowinstructions.

InNetLogo,therearefourtypesofagents:turtles,patches,links,andtheobserver.

Turtlesareagentsthatmovearoundintheworld.Theworldistwodimensionalandisdividedupintoagridofpatches.Eachpatchisasquarepieceof"ground"overwhichturtlescanmove.Linksareagentsthatconnecttwoturtles.Theobserverdoesn'thavealocation--youcanimagineitaslookingoutovertheworldofturtlesandpatches.

Theobserverdoesn'tobservepassively--itgivesinstructionstotheotheragents.

WhenNetLogostartsup,therearenoturtles.Theobservercanmakenewturtles.Patchescanmakenewturtlestoo.(Patchescan'tmove,butotherwisethey'rejustas"alive"asturtles.)

Patcheshavecoordinates.Thepatchatcoordinates(0,0)iscalledtheoriginandthecoordinatesoftheotherpatchesarethehorizontalandverticaldistancesfromthisone.Wecallthepatch'scoordinatespxcorandpycor.Justlikeinthestandardmathematicalcoordinateplane,pxcorincreasesasyoumovetotherightandpycorincreasesasyoumoveup.

Thetotalnumberofpatchesisdeterminedbythesettingsmin-pxcor,max-pxcor,min-pycor,andmax-pycorWhenNetLogostartsup,min-pxcor,max-pxcor,min-pycor,andmax-pycorare-16,16,-16,and16respectively.Thismeansthatpxcorandpycorbothrangefrom-16to16,sothereare33times33,or

1089patchestotal.(YoucanchangethenumberofpatcheswiththeSettingsbutton.)

Turtleshavecoordinatestoo:xcorandycor.Apatch'scoordinatesarealwaysintegers,butaturtle'scoordinatescanhavedecimals.Thismeansthataturtlecanbepositionedatanypointwithinitspatch;itdoesn'thavetobeinthecenterofthepatch.

Linksdonothavecoordinates.Everylinkhastwoends,andeachendisaturtle.Ifeitherturtledies,thelinkdiestoo.Alinkisrepresentedvisuallyasalineconnectingthetwoturtles.

Procedures

InNetLogo,commandsandreporterstellagentswhattodo.Acommandisanactionforanagenttocarryout,resultinginsomeeffect.Areporterisinstructionsforcomputingavalue,whichtheagentthen"reports"towhoeveraskedit.

Typically,acommandnamebeginswithaverb,suchas"create","die","jump","inspect",or"clear".Mostreporternamesarenounsornounphrases.

CommandsandreportersbuiltintoNetLogoarecalledprimitives.TheNetLogoDictionaryhasacompletelistofbuilt-incommandsandreporters.

Commandsandreportersyoudefineyourselfarecalledprocedures.Eachprocedurehasaname,precededbythekeywordtoorto-report,dependingonwhetheritisacommandprocedureorareporterprocedure.Thekeywordendmarkstheendofthecommandsintheprocedure.Onceyoudefineaprocedure,youcanuseitelsewhereinyourprogram.

Manycommandsandreporterstakeinputs--valuesthatthecommandorreporterusesincarryingoutitsactionsorcomputingitsresult.

Herearetwocommandprocedures:

to setup clear-all create-turtles 10 reset-ticksend

to go ask turtles [ fd 1 ;; forward 1 step rt random 10 ;; turn right lt random 10 ;; turn left ] tickend

Notetheuseofsemicolonstoadd"comments"totheprogram.Commentscanmakeyourcodeeasiertoreadandunderstand,buttheydon'taffectitsbehavior.

Inthisprogram,

setupandgoareuser-definedcommands.clear-all,create-turtles,reset-ticks,ask,lt("leftturn"),rt("rightturn")andtick,areallprimitivecommands.randomandturtlesareprimitivereporters.randomtakesasinglenumberasaninputandreportsarandomintegerthatislessthantheinput(inthiscase,between0and9).turtlesreportstheagentsetconsistingofalltheturtles.(We'llexplainaboutagentsetslater.)

setupandgocanbecalledbyotherprocedures,orbybuttons,orfromtheCommandCenter.

ManyNetLogomodelshaveaoncebuttonthatcallsaprocedurecalledsetupandaforeverbuttonthatcallsaprocedurecalledgo.

InNetLogo,youmayspecifywhichagents--turtles,patches,orlinks--aretoruneachcommand.Ifyoudon'tspecify,thecodeisrunbytheobserver.Inthecodeabove,theobserverusesasktomakethesetofallturtlesrunthecommandsbetweenthesquarebrackets.

clear-allandcreate-turtlescanonlyberunbytheobserver.fd,ontheotherhand,canonlyberunbyturtles.Someothercommandsandreporters,suchassetandticks,canberunbydifferentagenttypes.

Herearesomemoreadvancedfeaturesyoucantakeadvantageofwhendefiningyourownprocedures.

Procedureswithinputs

Procedurescantakeinputs,justlikemanyprimitivesdo.Tocreateaprocedurethatacceptsinputs,puttheirnamesinsquarebracketsaftertheprocedurename.Forexample:

to draw-polygon [num-sides len] ;; turtle procedure pen-down repeat num-sides [ fd len rt 360 / num-sides ]end

Elsewhereintheprogram,youmightusetheprocedurebyaskingtheturtlestoeachdrawanoctagonwithasidelengthequaltoitswhonumber:

ask turtles [ draw-polygon 8 who ]

Reporterprocedures

Justlikeyoucandefineyourowncommands,youcandefineyourownreporters.Youmustdotwospecialthings.First,useto-reportinsteadoftotobeginyourprocedure.Then,inthebodyoftheprocedure,usereporttoreportthevalueyouwanttoreport.

to-report absolute-value [number] ifelse number >= 0 [ report number ] [ report (- number) ]end

Variables

Agentvariables

Agentvariablesareplacestostorevalues(suchasnumbers)inanagent.Anagentvariablecanbeaglobalvariable,aturtlevariable,apatchvariable,oralinkvariable.

Ifavariableisaglobalvariable,thereisonlyonevalueforthevariable,andeveryagentcanaccessit.Youcanthinkofglobalvariablesasbelongingtotheobserver.

Turtle,patch,andlinkvariablesaredifferent.Eachturtlehasitsownvalueforeveryturtlevariable.Thesamegoesforpatchesandlinks.

SomevariablesarebuiltintoNetLogo.Forexample,allturtlesandlinkshaveacolorvariable,andallpatcheshaveapcolorvariable.(Thepatchvariablebeginswith"p"soitdoesn'tgetconfusedwiththeturtlevariable,sinceturtleshavedirectaccesstopatchvariables.)Ifyousetthevariable,theturtleorpatchchangescolor.(Seenextsectionfordetails.)

Otherbuilt-inturtlevariablesincludingxcor,ycor,andheading.Otherbuilt-inpatchvariablesincludepxcorandpycor.(Thereisacompletelisthere.)

Youcanalsodefineyourownvariables.Youcanmakeaglobalvariablebyaddingaswitch,slider,chooser,orinputboxtoyourmodel,orbyusingtheglobalskeywordatthebeginningofyourcode,likethis:

globals [score]

Youcanalsodefinenewturtle,patchandlinkvariablesusingtheturtles-own,patches-ownandlinks-ownkeywords,likethis:

turtles-own [energy speed]patches-own [friction]links-own [strength]

Thesevariablescanthenbeusedfreelyinyourmodel.Usethesetcommandtosetthem.(Anyvariableyoudon'tsethasastartingvalueofzero.)

Globalvariablescanbereadandsetatanytimebyanyagent.Aswell,aturtlecanreadandsetpatchvariablesofthepatchitisstandingon.Forexample,thiscode:

ask turtles [ set pcolor red ]

causeseveryturtletomakethepatchitisstandingonred.(Becausepatchvariablesaresharedbyturtlesinthisway,youcan'thaveaturtlevariableandapatchvariablewiththesamename.)

Inothersituationswhereyouwantanagenttoreadadifferentagent'svariable,youcanuseof.Example:

show [color] of turtle 5;; prints current color of turtle with who number 5

Youcanalsouseofwithamorecomplicatedexpressionthanjustavariablename,forexample:

show [xcor + ycor] of turtle 5;; prints the sum of the x and y coordinates of;; turtle with who number 5

Localvariables

Alocalvariableisdefinedandusedonlyinthecontextofaparticularprocedureorpartofaprocedure.Tocreatealocalvariable,usetheletcommand.Ifyouuseletatthetopofaprocedure,thevariablewillexistthroughouttheprocedure.Ifyouuseitinsideasetofsquarebrackets,forexampleinsidean"ask",thenitwillexistonlyinsidethosebrackets.

to swap-colors [turtle1 turtle2] let temp [color] of turtle1 ask turtle1 [ set color [color] of turtle2 ] ask turtle2 [ set color temp ]end

Tickcounter

InmanyNetLogomodels,timepassesindiscretesteps,called"ticks".NetLogoincludesabuilt-intickcountersoyoucankeeptrackofhowmanytickshavepassed.

Thecurrentvalueofthetickcounterisshownabovetheview.(YoucanusetheSettingsbuttontohidethetickcounter,orchangetheword"ticks"tosomethingelse.)

Incode,toretrievethecurrentvalueofthetickcounter,usetheticksreporter.Thetickcommandadvancesthetickcounterby1.Theclear-allcommandclearsthetickcounteralongwitheverythingelse.

Whenthetickcounterisclear,it'sanerrortotrytoreadormodifyit.Usethereset-tickscommandwhenyourmodelisdonesettingup,tostartthetickcounter.

Ifyourmodelissettousetick-basedupdates,thenthetickcommandwillusuallyalsoupdatetheview.Seethelatersection,ViewUpdates.

Whentotick

Usereset-ticksattheendofyoursetupprocedure.

Usetickattheendofyourgoprocedure.

to setup clear-all create-turtles 10 reset-ticksend

to go ask turtles [ fd 1 ] tickend

Fractionalticks

Inmostmodels,thetickcounterstartsat0andgoesup1atatime,fromintegertointeger.Butit'salsopossibleforthetickcountertotakeonin-betweenfloatingpointvalues.

Toadvancethetickcounterbyafractionalamount,usethetick-advancecommand.Thiscommandtakesanumericinputspecifyinghowfartoadvancethetickcounter.

Atypicaluseoffractionalticksistoapproximatecontinuousorcurvedmotion.See,forexample,theGasLabmodelsintheModelsLibrary(underChemistry&Physics).Thesemodelscalculatetheexacttimeatwhichafutureeventistooccur,thenadvancethetickcountertoexactlythattime.

Colors

NetLogorepresentscolorsindifferentways.Acolorcanbenumberintherange0to140,withtheexceptionof140itself.BelowisachartshowingtherangeofsuchcolorsyoucanuseinNetLogo.

Thechartshowsthat:

Someofthecolorshavenames.(Youcanusethesenamesinyourcode.)Everynamedcolorexceptblackandwhitehasanumberendingin5.Oneithersideofeachnamedcoloraredarkerandlightershadesofthecolor.0ispureblack.9.9ispurewhite.10,20,andsoonareallsodarktheyareverynearlyblack.19.9,29.9andsoonareallsolighttheyareverynearlywhite.

CodeExample:ThecolorchartwasmadeinNetLogowiththeColorChartExamplemodel.

Ifyouuseanumberoutsidethe0to140range,NetLogowillrepeatedlyaddorsubtract140fromthenumberuntilitisinthe0to140range.Forexample,25isorange,so165,305,445,andsoonareorangetoo,andsoare-115,-255,-395,etc.Thiscalculationisdoneautomaticallywheneveryousettheturtlevariablecolororthepatchvariablepcolor.Shouldyouneedtoperformthiscalculationinsomeothercontext,usethewrap-colorprimitive.

Ifyouwantacolorthat'snotonthechart,moreexistbetweentheintegers.Forexample,26.5isashadeoforangehalfwaybetween26and27.Thisdoesn'tmeanyoucanmakeanycolorinNetLogo;theNetLogocolorspaceisonlyasubsetofallpossiblecolors.Itcontainsonlyafixedsetofdiscretehues(onehueperrowofthechart).Startingfromoneofthosehues,youcaneitherdecreaseitsbrightness(darkenit)ordecreaseitssaturation(lightenit),butyoucannotdecreasebothbrightnessandsaturation.Also,onlythefirstdigitafterthedecimalpointissignificant.Thus,colorvaluesareroundeddowntothenext0.1,soforexample,there'snovisibledifferencebetween26.5and26.52or26.58.

Colorprimitives

Thereareafewprimitivesthatarehelpfulforworkingwithcolors.

Wehavealreadymentionedthewrap-colorprimitive.

Thescale-colorprimitiveisusefulforconvertingnumericdataintocolors.

shade-of?willtellyouiftwocolorsareboth"shades"ofthesamebasichue.Forexample,shade-of?orange 27istrue,because27isalightershadeoforange.

CodeExample:Scale-colorExampledemonstratesthescale-colorreporter.

RGBandRGBAColors

NetLogoalsorepresentscolorsasRGB(red/green/blue)listsandRGBA(red/green/blue/alpha)lists.WhenusingRGBcolorsthefullrangeofcolorsisavailabletoyou.RGBAcolorsallowallthecolorsthatRGBallowsandyoucanalsovarythetransparencyofacolor.RGBandRGBAlistsaremadeupofthreeorfourintegers,respectively,between0and255ifanumberisoutsidethatrange255isrepeatedlysubtracteduntilitisintherange.YoucansetanycolorvariablesinNetLogo(colorforturtlesandlinksandpcolorforpatches)toanRGBlistandthatagentwillberenderedappropriately.Soyoucansetthecolorofpatch00topureredusingthefollowingcode:

set pcolor [255 0 0]

Turtles,links,andlabelscanallcontainRGBAlistsastheircolorvariables,however,patchescannothaveRGBApcolorsYoucansetthecolorofaturtletobeapproximatelyhalftransparentpureredwiththefollowingcode:

set color [255 0 0 125]

YoucanconvertfromaNetLogocolortoRGBorHSB(hue/saturation/brightness)usingextract-hsbandextract-rgb.YoucanusergbtogeneratergblistsandhsbtoconvertfromanHSBcolortoRGB.

SincemanycolorsaremissingfromtheNetLogocolorspace,approximate-hsbandapproximate-rgb

oftencan'tgiveyoutheexactcoloryouaskfor,buttheytrytocomeascloseaspossible.

Example:youcanchangeanyturtlefromit'sexistingNetLogocolortoahalftransparentversionofthatcolorusing:

set color lput 125 extract-rgb color

CodeExamples:HSBandRGBExample(letsyouexperimentwiththeHSBandRGBcolorsystems),TransparencyExample

ColorSwatchesdialog

TheColorSwatchesdialoghelpsyouexperimentwithandchoosecolors.OpenitbychoosingColorSwatchesontheToolsMenu.

Whenyouclickonacolorswatch(oracolorbutton),thatcolorwillbeshownagainstothercolors.Inthebottomleft,thecodeforthecurrentlyselectedcolorisdisplayed(forexample,red + 2)soyoucancopyandpasteitintoyourcode.Onthebottomrighttherearethreeincrementoptions,1,0.5,and0.1.Thesenumbersindicatethedifferencebetweentwoadjacentswatches.Whentheincrementis1thereare10differentshadesineachrow;whentheincrementis0.1thereare100differentshadesineachrow.0.5isanintermediatesetting.

Ask

NetLogousestheaskcommandtogivecommandstoturtles,patches,andlinks.Allcodetoberunbyturtlesmustbelocatedinaturtle"context".Youcanestablishaturtlecontextinanyofthreeways:

Inabutton,bychoosing"Turtles"fromthepopupmenu.Anycodeyouputinthebuttonwillberunbyallturtles.IntheCommandCenter,bychoosing"Turtles"fromthepopupmenu.Anycommandsyouenterwillberunbyalltheturtles.Byusingask turtles,hatch,orothercommandswhichestablishaturtlecontext.

Thesamegoesforpatches,links,andtheobserver,exceptthatyoucannotasktheobserver.Anycodethatisnotinsideanyaskisbydefaultobservercode.

Here'sanexampleoftheuseofaskinaNetLogoprocedure:

to setup clear-all create-turtles 100 ;; create 100 turtles with random headings ask turtles [ set color red ;; turn them red fd 50 ] ;; spread them around ask patches [ if pxcor > 0 ;; patches on the right side [ set pcolor green ] ] ;; of the view turn green reset-ticksend

ThemodelsintheModelsLibraryarefullofotherexamples.AgoodplacetostartlookingisintheCodeExamplessection.

Usually,theobserverusesasktoaskallturtles,allpatchesoralllinkstoruncommands.Youcanalsouseasktohaveanindividualturtle,patchorlinkruncommands.Thereportersturtle,patch,linkandpatch-atareusefulforthistechnique.Forexample:

to setup clear-all crt 3 ;; make 3 turtles ask turtle 0 ;; tell the first one... [ fd 1 ] ;; ...to go forward ask turtle 1 ;; tell the second one... [ set color green ] ;; ...to become green ask turtle 2 ;; tell the third one... [ rt 90 ] ;; ...to turn right ask patch 2 -2 ;; ask the patch at (2,-2) [ set pcolor blue ] ;; ...to become blue ask turtle 0 ;; ask the first turtle [ ask patch-at 1 0 ;; ...to ask patch to the east [ set pcolor red ] ] ;; ...to become red ask turtle 0 ;; tell the first turtle... [ create-link-with turtle 1 ] ;; ...make a link with the second ask link 0 1 ;; tell the link between turtle 0 and 1 [ set color blue ] ;; ...to become blue reset-ticksend

Everyturtlecreatedhasawhonumber.Thefirstturtlecreatedisnumber0,thesecondturtlenumber1,andsoforth.

Theturtleprimitivereportertakesawhonumberasaninput,andreportstheturtlewiththatwhonumber.Thepatchprimitivereportertakesvaluesforpxcorandpycorandreportsthepatchwiththosecoordinates.Thelinkprimitivetakestwoinputs,thewhonumbersofthetwoturtlesitconnects.Andthepatch-atprimitivereportertakesoffsets:distances,inthexandydirections,fromthefirstagent.Intheexampleabove,theturtlewithwhonumber0isaskedtogetthepatcheast(andnopatchesnorth)ofitself.

Youcanalsoselectasubsetofturtles,orasubsetofpatches,orasubsetoflinksandaskthemtodosomething.Thisinvolvesusingagentsets.Thenextsectionexplainsthemindetail.

Whenyouaskasetofagentstorunmorethanonecommand,eachagentmustfinishbeforethenextagentstarts.Oneagentrunsallofthecommands,thenthenextagentrunsallofthem,andsoon.Forexample,ifyouwrite:

ask turtles [ fd 1 set color red ]

firstoneturtlemovesandturnsred,thenanotherturtlemovesandturnsred,andsoon.

Butifyouwriteitthisway:

ask turtles [ fd 1 ]ask turtles [ set color red ]

firstalltheturtlesmove,thentheyallturnred.

Agentsets

Anagentsetisexactlywhatitsnameimplies,asetofagents.Anagentsetcancontaineitherturtles,patchesorlinks,butnotmorethanonetypeatonce.

Anagentsetisnotinanyparticularorder.Infact,it'salwaysinarandomorder.Andeverytimeyouuseit,theagentsetisinadifferentrandomorder.Thishelpsyoukeepyourmodelfromtreatinganyparticularturtles,patchesorlinksdifferentlyfromanyothers(unlessyouwantthemtobe).Sincetheorderisrandomeverytime,nooneagentalwaysgetstogofirst.

You'veseentheturtlesprimitive,whichreportstheagentsetofallturtles,thepatchesprimitive,whichreportstheagentsetofallpatchesandthelinksprimitivewhichreportstheagentsetofalllinks.

Butwhat'spowerfulabouttheagentsetconceptisthatyoucanconstructagentsetsthatcontainonlysometurtles,somepatchesorsomelinks.Forexample,alltheredturtles,orthepatcheswithpxcorevenlydivisiblebyfive,ortheturtlesinthefirstquadrantthatareonagreenpatchorthelinksconnectedtoturtle0.Theseagentsetscanthenbeusedbyaskorbyvariousreportersthattakeagentsetsasinputs.

Onewayistouseturtles-hereorturtles-at,tomakeanagentsetcontainingonlytheturtlesonmypatch,oronlytheturtlesonsomeotherpatchatsomexandyoffsets.There'salsoturtles-onsoyoucangetthesetofturtlesstandingonagivenpatchorsetofpatches,orthesetofturtlesstandingonthesamepatchasagiventurtleorsetofturtles.

Herearesomemoreexamplesofhowtomakeagentsets:

;; all other turtles:other turtles;; all other turtles on this patch:other turtles-here;; all red turtles:turtles with [color = red];; all red turtles on my patchturtles-here with [color = red];; patches on right side of viewpatches with [pxcor > 0];; all turtles less than 3 patches awayturtles in-radius 3;; the four patches to the east, north, west, and southpatches at-points [[1 0] [0 1] [-1 0] [0 -1]];; shorthand for those four patchesneighbors4;; turtles in the first quadrant that are on a green patchturtles with [(xcor > 0) and (ycor > 0) and (pcolor = green)];; turtles standing on my neighboring four patchesturtles-on neighbors4;; all the links connected to turtle 0[my-links] of turtle 0

Notetheuseofothertoexcludethisagent.Thisiscommon.

Onceyouhavecreatedanagentset,herearesomesimplethingsyoucando:

UseasktomaketheagentsintheagentsetdosomethingUseany?toseeiftheagentsetisemptyUseall?toseeifeveryagentinanagentsetsatisfiesacondition.Usecounttofindoutexactlyhowmanyagentsareintheset

Andherearesomemorecomplexthingsyoucando:

Pickarandomagentfromthesetusingone-of.Forexample,wecanmakearandomlychosenturtleturngreen:

ask one-of turtles [ set color green ]

Ortellarandomlychosenpatchtosproutanewturtle:

ask one-of patches [ sprout 1 ]

Usethemax-one-oformin-one-ofreporterstofindoutwhichagentisthemostorleastalongsomescale.Forexample,toremovetherichestturtle,youcouldsay

ask max-one-of turtles [sum assets] [ die ]

Makeahistogramoftheagentsetusingthehistogramcommand(incombinationwithof).Useoftomakealistofvalues,oneforeachagentintheagentset.ThenuseoneofNetLogo'slistprimitivestodosomethingwiththelist.(Seethe"Lists"sectionbelow.)Forexample,tofindouthowrichturtlesareontheaverage,youcouldsay

show mean [sum assets] of turtles

Useturtle-set,patch-setandlink-setreporterstomakenewagentsetsbygatheringtogetheragentsfromavarietyofpossiblesources.Useno-turtles,no-patchesandno-linksreporterstomakeemptyagentsets.Checkwhethertwoagentsetsareequalusing=or!=.Usemember?toseewhetheraparticularagentisamemberofanagentset.

Thisonlyscratchesthesurface.SeetheModelsLibraryformanymoreexamples,andconsulttheNetLogoDictionaryformoreinformationaboutalloftheagentsetprimitives.

MoreexamplesofusingagentsetsareprovidedintheindividualentriesfortheseprimitivesintheNetLogoDictionary.

Specialagentsets

Theagentsetsturtlesandlinkshavespecialbehaviorbecausetheyalwaysholdthesetsofallturtlesandalllinks.Therefore,theseagentsetscangrow.

Thefollowinginteractionshowsthespecialbehavior.AssumetheCodetabhasglobals [g].Then:

observer> clear-allobserver> create-turtles 5observer> set g turtlesobserver> print count g5observer> create-turtles 5observer> print count g10observer> set g turtle-set turtlesobserver> print count g10observer> create-turtles 5observer> print count g10observer> print count turtles15

Theturtlesagentsetgrowswhennewturtlesareborn,butotheragentsetsdon'tgrow.IfIwriteturtle-set turtles,Igetanew,normalagentsetcontainingjusttheturtlesthatcurrentlyexist.Newturtlesdon'tjoinwhenthey'reborn.

Breedagentsetsarespecialinthesamewayasturtlesandlinks.Breedsareintroducedandexplainedbelow.

Agentsetsandlists

Earlier,wesaidthatagentsetsarealwaysinrandomorder,adifferentrandomordereverytime.Ifyouneedyouragentstodosomethinginafixedorder,youneedtomakealistoftheagentsinstead.SeetheListssectionbelow.

CodeExample:AskOrderingExample

Breeds

NetLogoallowsyoutodefinedifferent"breeds"ofturtlesandbreedsoflinks.Onceyouhavedefinedbreeds,youcangoonandmakethedifferentbreedsbehavedifferently.Forexample,youcouldhavebreedscalledsheepandwolves,andhavethewolvestrytoeatthesheeporyoucouldhavelinkbreedscalledstreetsandsidewalkswherefoottrafficisroutedonsidewalksandcartrafficisroutedonstreets.

Youdefineturtlebreedsusingthebreedkeyword,atthetopoftheCodetab,beforeanyprocedures:

breed [wolves wolf]breed [sheep a-sheep]

Youcanrefertoamemberofthebreedusingthesingularform,justliketheturtlereporter.Whenprinted,membersofthebreedwillbelabeledwiththesingularname.

Somecommandsandreportershavethepluralnameofthebreedinthem,suchascreate-<breeds>.Othershavethesingularnameofthebreedinthem,suchas<breed>

Theorderinwhichbreedsaredeclaredisalsotheorderinwhichtheyarelayeredintheview.Sobreedsdefinedlaterwillappearontopofbreedsdefinedearlier;inthisexample,sheepwillbedrawnoverwolves.

Whenyoudefineabreedsuchassheep,anagentsetforthatbreedisautomaticallycreated,sothatalloftheagentsetcapabilitiesdescribedaboveareimmediatelyavailablewiththesheepagentset.

Thefollowingnewprimitivesarealsoautomaticallyavailableonceyoudefineabreed:create-sheep,hatch-sheep,sprout-sheep,sheep-here,sheep-at,sheep-on,andis-a-sheep?.

Also,youcanusesheep-owntodefinenewturtlevariablesthatonlyturtlesofthegivenbreedhave.(It'sallowedformorethanonebreedtoownthesamevariable.)

Aturtle'sbreedagentsetisstoredinthebreedturtlevariable.Soyoucantestaturtle'sbreed,likethis:

if breed = wolves [ ... ]

Notealsothatturtlescanchangebreeds.Awolfdoesn'thavetoremainawolfitswholelife.Let'schangearandomwolfintoasheep:

ask one-of wolves [ set breed sheep ]

Theset-default-shapeprimitiveisusefulforassociatingcertainturtleshapeswithcertainbreeds.Seethesectiononshapesbelow.

Whonumbersareassignedirrespectiveofbreeds.Ifyoualreadyhaveafrog 0,thenthefirstmousewillbemouse 1,notmouse 0,sincethewhonumber0isalreadytaken.

Hereisaquickexampleofusingbreeds:

breed [mice mouse]breed [frogs frog]mice-own [cheese]to setup clear-all create-mice 50

[ set color white set cheese random 10 ] create-frogs 50 [ set color green ] reset-ticksend

CodeExample:BreedsandShapesExample

Linkbreeds

Linkbreedsareverysimilartoturtlebreeds,however,thereareafewdifferences.

Whenyoudeclarealinkbreedyoumustdeclarewhetheritisabreedofdirectedorundirectedlinksbyusingthedirected-link-breedandundirected-link-breedkeywords.

directed-link-breed [streets street]undirected-link-breed [friendships friendship]

Onceyouhavecreatedabreededlinkyoucannotcreateunbreededlinksandviceversa.(Youcan,however,havedirectedandundirectedlinksinthesameworld,justnotinthesamebreed)

Unlikewithturtlebreedsthesingularbreednameisrequiredforlinkbreeds,asmanyofthelinkcommandsandreportsusethesingularname,suchas<link-breed>-neighbor?.

Thefollowingprimitivesarealsoautomaticallyavailableonceyoudefineadirectedlinkbreed:create-street-fromcreate-streets-fromcreate-street-tocreate-streets-toin-street-neighbor?in-street-neighborsin-street-frommy-in-streetsmy-out-streetsout-street-neighbor?out-street-neighborsout-street-to

Andthefollowingareautomaticallyavailablewhenyoudefineanundirectedlinkbreed:create-friendship-withcreate-friendships-withfriendship-neighbor?friendship-neighborsfriendship-withmy-friendships

Multiplelinkbreedsmaydeclarethesame-ownvariable,butavariablemaynotbesharedbetweenaturtlebreedandalinkbreed.

Justaswithturtlebreedstheorderinwhichlinkbreedsaredeclareddefinestheorderinwhichthelinksaredrawn,sothefriendshipswillalwaysbeontopofstreets(ifforsomereasonthesebreedswereinthesamemodel).Youcanalsouse<link-breeds>-owntodeclarevariablesofeachlinkbreedseparately.

Youcanchangethebreedofalinkwithset breed.(However,youcannotchangeabreededlinktoanunbreededone,topreventhavingbreededandunbreededlinksinthesameworld.)

ask one-of friendships [ set breed streets ]ask one-of friendships [ set breed links ] ;; produces a runtime error

set-default-shapemayalsobeusedwithlinkbreedstoassociateitwithaparticularlinkshape.

CodeExample:LinkBreedsExample

Buttons

Buttonsintheinterfacetabprovideaneasywaytocontrolthemodel.Typicallyamodelwillhaveatleasta"setup"button,tosetuptheinitialstateoftheworld,anda"go"buttontomakethemodelruncontinuously.Somemodelswillhaveadditionalbuttonsthatperformotheractions.

AbuttoncontainssomeNetLogocode.Thatcodeisrunwhenyoupressthebutton.

Abuttonmaybeeithera"oncebutton",ora"foreverbutton".Youcancontrolthisbyeditingthebuttonandcheckingoruncheckingthe"Forever"checkbox.Oncebuttonsruntheircodeonce,thenstopandpopbackup.Foreverbuttonskeeprunningtheircodeoverandoveragain.

Aforeverbuttonstopsiftheuserpressesthebuttonagaintostopit.Thebuttonwaitsuntilthecurrentiterationhasfinished,thenpopsup.

Aforeverbuttoncanalsobestoppedfromcode.Iftheforeverbuttondirectlycallsaprocedure,thenwhenthatprocedurestops,thebuttonstops.(Inaturtleorpatchforeverbutton,thebuttonwon'tstopuntileveryturtleorpatchstops--asingleturtleorpatchdoesn'thavethepowertostopthewholebutton.)

Normally,abuttonislabeledwiththecodethatitruns.Forexample,abuttonthatsays"go"onitusuallycontainsthecode"go",whichmeans"runthegoprocedure".(ProceduresaredefinedintheCodetab;seebelow.)Butyoucanalsoeditabuttonandentera"displayname"forthebutton,whichisatextthatappearsonthebuttoninsteadofthecode.Youmightusethisfeatureifyouthinktheactualcodewouldbeconfusingtoyourusers.

Whenyouputcodeinabutton,youmustalsospecifywhichagentsyouwanttorunthatcode.Youcanchoosetohavetheobserverrunthecode,orallturtles,orallpatches,oralllinks.(Ifyouwantthecodetoberunbyonlysometurtlesorsomepatches,youcouldmakeanobserverbutton,andthenhavetheobserverusetheaskcommandtoaskonlysomeoftheturtlesorpatchestodosomething.)

Whenyoueditabutton,youhavetheoptiontoassignan"actionkey".Thismakesthatkeyonthekeyboardbehavejustlikeabuttonpress.Ifthebuttonisaforeverbutton,itwillstaydownuntilthekeyispressedagain(orthebuttonisclicked).Actionkeysareparticularlyusefulforgamesoranymodelwhererapidtriggeringofbuttonsisneeded.

Buttonstaketurns

Morethanonebuttoncanbepressedatatime.Ifthishappens,thebuttons"taketurns",whichmeansthatonlyonebuttonrunsatatime.Eachbuttonrunsitscodeallthewaythroughoncewhiletheotherbuttonswait,thenthenextbuttongetsitsturn.

Inthefollowingexamples,"setup"isaoncebuttonand"go"isaforeverbutton.

Example#1:Theuserpresses"setup",thenpresses"go"immediately,beforethe"setup"haspoppedbackup.Result:"setup"finishesbefore"go"starts.

Example#2:Whilethe"go"buttonisdown,theuserpresses"setup".Result:the"go"buttonfinishesitscurrentiteration.Thenthe"setup"buttonruns.Then"go"startsrunningagain.

Example#3:Theuserhastwoforeverbuttonsdownatthesametime.Result:firstonebuttonrunsitscodeallthewaythrough,thentheotherrunsitscodeallthewaythrough,andsoon,alternating.

Notethatifonebuttongetsstuckinaninfiniteloop,thennootherbuttonswillrun.

Turtle,patch,andlinkforeverbuttons

Thereisasubtledifferencebetweenputtingcommandsinaturtle,patchorlinkforeverbutton,andputtingthesamecommandsinanobserverbuttonthatdoesask turtles,ask patchesorask links.An"ask"doesn'tcompleteuntilalloftheagentshavefinishedrunningallofthecommandsinthe"ask".Sotheagents,astheyallrunthecommandsconcurrently,canbeoutofsyncwitheachother,buttheyallsyncupagainattheendoftheask.Thesameisn'ttrueofturtle,patchandlinkforeverbuttons.Sinceaskwasnotused,eachturtleorpatchrunsthegivencodeoverandoveragain,sotheycanbecome(andremain)outofsyncwitheachother.

Atpresent,thiscapabilityisveryrarelyusedinthemodelsinourModelsLibrary.AmodelthatdoesusethecapabilityistheTermitesmodel,intheBiologysectionofSampleModels.The"go"buttonisaturtleforeverbutton,soeachtermiteproceedsindependentlyofeveryothertermite,andtheobserverisnotinvolvedatall.Thismeansthatif,forexample,youwantedtoaddticksand/oraplottothemodel,youwouldneedtoaddasecondforeverbutton(anobserverforeverbutton),andrunbothforeverbuttonsat

thesametime.NotealsothatamodellikethiscannotbeusedwithBehaviorSpace.

CodeExample:StateMachineExampleshowshowTermitescanberecodedinatick-basedway,withoutusingaturtleforeverbutton.

Atpresent,NetLogohasnowayforoneforeverbuttontostartanother.Buttonsareonlystartedwhenyoupressthem.

Lists

Inthesimplestmodels,eachvariableholdsonlyonepieceofinformation,usuallyanumberorastring.Listsletyoustoremultiplepiecesofinformationinasinglevaluebycollectingthatinformationinalist.Eachvalueinthelistcanbeanytypeofvalue:anumber,orastring,anagentoragentset,orevenanotherlist.

ListsallowfortheconvenientpackagingofinformationinNetLogo.Ifyouragentscarryoutarepetitivecalculationonmultiplevariables,itmightbeeasiertohavealistvariable,insteadofmultiplenumbervariables.Severalprimitivessimplifytheprocessofperformingthesamecomputationoneachvalueinalist.

TheNetLogoDictionaryhasasectionthatlistsallofthelist-relatedprimitives.

Constantlists

Youcanmakealistbysimplyputtingthevaluesyouwantinthelistbetweenbrackets,likethis:setmylist [2 4 6 8].Notethattheindividualvaluesareseparatedbyspaces.Youcanmakeliststhatcontainnumbersandstringsthisway,aswellaslistswithinlists,forexample[[2 4] [3 5]].

Theemptylistiswrittenbyputtingnothingbetweenthebrackets,likethis:[].

Buildinglistsonthefly

Ifyouwanttomakealistinwhichthevaluesaredeterminedbyreporters,asopposedtobeingaseriesofconstants,usethelistreporter.Thelistreporteracceptstwootherreporters,runsthem,andreportstheresultsasalist.

IfIwantedalisttocontaintworandomvalues,Imightusethefollowingcode:

set random-list list (random 10) (random 20)

Thiswillsetrandom-listtoanewlistoftworandomintegerseachtimeitruns.

Tomakelongerorshorterlists,youcanusethelistreporterwithfewerormorethantwoinputs,butinordertodoso,youmustenclosetheentirecallinparentheses,e.g.:

(list random 10)(list random 10 random 20 random 30)

Formoreinformation,seeVaryingnumberofinputs.

Somekindsoflistsaremosteasilybuiltusingthen-valuesreporter,whichallowsyoutoconstructalistofaspecificlengthbyrepeatedlyrunningagivenreporter.Youcanmakealistofthesamevaluerepeated,orallthenumbersinarange,oralotofrandomnumbers,ormanyotherpossibilities.Seedictionaryentryfordetailsandexamples.

Theofprimitiveletsyouconstructalistfromanagentset.Itreportsalistcontainingeachagent'svalueforthegivenreporter.(Thereportercouldbeasimplevariablename,oramorecomplexexpression--evenacalltoaproceduredefinedusingto-report.)Acommonidiomis

max [...] of turtlessum [...] of turtles

andsoon.

Youcancombinetwoormorelistsusingthesentencereporter,whichconcatenateslistsbycombiningtheircontentsintoasingle,largerlist.Likelist,sentencenormallytakestwoinputs,butcanacceptanynumberofinputsifthecallissurroundedbyparentheses.

Changinglistitems

Technically,listscan'tbemodified,butyoucanconstructnewlistsbasedonoldlists.Ifyouwantthenewlisttoreplacetheoldlist,useset.Forexample:

set mylist [2 7 5 Bob [3 0 -2]]; mylist is now [2 7 5 Bob [3 0 -2]]set mylist replace-item 2 mylist 10; mylist is now [2 7 10 Bob [3 0 -2]]

Thereplace-itemreportertakesthreeinputs.Thefirstinputspecifieswhichiteminthelististobechanged.0meansthefirstitem,1meanstheseconditem,andsoforth.

Toaddanitem,say42,totheendofalist,usethelputreporter.(fputaddsanitemtothebeginningofalist.)

set mylist lput 42 mylist; mylist is now [2 7 10 Bob [3 0 -2] 42]

Butwhatifyouchangedyourmind?Thebut-last(blforshort)reporterreportsallthelistitemsbutthelast.

set mylist but-last mylist; mylist is now [2 7 10 Bob [3 0 -2]]

Supposeyouwanttogetridofitem0,the2atthebeginningofthelist.

set mylist but-first mylist; mylist is now [7 10 Bob [3 0 -2]]

Supposeyouwantedtochangethethirditemthat'snestedinsideitem3from-2to9?Thekeyistorealizethatthenamethatcanbeusedtocallthenestedlist[30-2]isitem 3 mylist.Thenthereplace-itemreportercanbenestedtochangethelist-within-a-list.Theparenthesesareaddedforclarity.

set mylist (replace-item 3 mylist (replace-item 2 (item 3 mylist) 9)); mylist is now [7 10 Bob [3 0 9]]

Iteratingoverlists

Ifyouwanttodosomeoperationoneachiteminalistinturn,theforeachcommandandthemapreportermaybehelpful.

foreachisusedtorunacommandorcommandsoneachiteminalist.Ittakesaninputlistandacommandnameorblockofcommands,likethis:

foreach [1 2 3] show=> 1=> 2=> 3foreach [2 4 6] [ n -> crt n

show (word "created " n " turtles") ]=> created 2 turtles=> created 4 turtles=> created 6 turtles

Intheblock,thevariablenholdsthecurrentvaluefromtheinputlist.

Herearesomemoreexamplesofforeach:

foreach [1 2 3] [ steps -> ask turtles [ fd steps ] ];; turtles move forward 6 patchesforeach [true false true true] [ should-move? -> ask turtles [ if should-move? [ fd 1 ] ] ];; turtles move forward 3 patches

mapissimilartoforeach,butitisareporter.Ittakesaninputlistandareporternameorreporterblock.Notethatunlikeforeach,thereportercomesfirst,likethis:

show map round [1.2 2.2 2.7];; prints [1 2 3]

mapreportsalistcontainingtheresultsofapplyingthereportertoeachitemintheinputlist.Again,usethevariablenamedintheanonymousprocedure(xintheexamplesbelow)torefertothecurrentiteminthelist.

Hereareacouplemoreexamplesofmap:

show map [ x -> x < 0 ] [1 -1 3 4 -2 -10];; prints [false true false false true true]show map [ x -> x * x ] [1 2 3];; prints [1 4 9]

Besidesmapandforeach,otherprimitivesforprocessingwholelistsinaconfigurablewayincludefilter,reduce,andsort-by.

Theseprimitivesaren'talwaysthesolutionforeverysituationinwhichyouwanttooperateonanentirelist.Insomesituations,youmayneedtousesomeothertechniquesuchasaloopusingrepeatorwhile,orarecursiveprocedure.

Theblocksofcodewe'regivingtomapandforeachintheseexamplesareactuallyanonymousprocedures.AnonymousproceduresareexplainedinmoredetailinAnonymousprocedures,below.

Varyingnumberofinputs

Somecommandsandreportersinvolvinglistsandstringsmaytakeavaryingnumberofinputs.Inthesecases,inordertopassthemanumberofinputsotherthantheirdefault,theprimitiveanditsinputsmustbesurroundedbyparentheses.Herearesomeexamples:

show list 1 2=> [1 2]show (list 1 2 3 4)=> [1 2 3 4]show (list)=> []

Notethateachofthesespecialprimitiveshasadefaultnumberofinputsforwhichnoparenthesesarerequired.Theprimitiveswhichhavethiscapabilityarelist,word,sentence,map,foreach,run,andrunresult.

Listsofagents

Earlier,wesaidthatagentsetsarealwaysinrandomorder,adifferentrandomordereverytime.Ifyouneedyouragentstodosomethinginafixedorder,youneedtomakealistoftheagentsinstead.

Therearetwoprimitivesthathelpyoudothis,sortandsort-by.

Bothsortandsort-bycantakeanagentsetasinput.Theresultisalwaysanewlist,containingthesameagentsastheagentsetdid,butinaparticularorder.

Ifyouusesortonanagentsetofturtles,theresultisalistofturtlessortedinascendingorderbywhonumber.

Ifyouusesortonanagentsetofpatches,theresultisalistofpatchessortedleft-to-right,top-to-bottom.

Ifyouusesortonanagentsetoflinks,theresultisalistoflinks,sortedinascendingorderfirstbyend1thenbyend2anyremainingtiesareresolvedbybreedintheordertheyaredeclaredintheCodetab.

Ifyouneeddescendingorderinstead,youcancombinereversewithsort,forexamplereverse sortturtles.

Ifyouwantyouragentstobeorderedbysomeothercriterionthanthestandardonessortuses,you'llneedtousesort-byinstead.

Here'sanexample:

sort-by [ [a b] -> [size] of a < [size] of b ] turtles

Thisreturnsalistofturtlessortedinascendingorderbytheirturtlevariablesize.

There'sacommonpatterntogetalistofagentsinarandomorder,usingacombinationofofandself,intherarecasethatyoucannotjustuseask:

[self] of my-agentset

Askingalistofagents

Onceyouhavealistofagents,youmightwanttoaskthemeachtodosomething.Todothis,usetheforeachandaskcommandsincombination,likethis:

foreach sort turtles [ the-turtle -> ask the-turtle [ ... ]]

Thiswillaskeachturtleinascendingorderbywhonumber.Substitute"patches"for"turtles"toaskpatchesinleft-to-right,top-to-bottomorder.

Notethatyoucan'tuseaskdirectlyonalistofturtles.askonlyworkswithagentsetsandsingleagents.

Performanceoflists

ThedatastructureunderlyingNetLogo'slistsisasophisticatedtree-baseddatastructureonwhichmostoperationsruninnear-constanttime.Thatincludesfput,lput,butfirst,butlast,length,item,andreplace-item.

Oneexceptiontothefast-performanceruleisthatconcatenatingtwolistswithsentencerequirestraversingandcopyingthewholesecondlist.(Thismaybefixedinafutureversion.)

Technically,"near-constanttime"isactuallylogarithmictime,proportionaltothedepthoftheunderlyingtree,butthesetreeshavelargenodesandahighbranchingfactor,sotheyarenevermorethanafewlevelsdeep.Thismeansthatchangescanbemadeinatmostafewsteps.Thetreesareimmutable,buttheysharestructurewitheachother,sothewholetreedoesn'tneedtobecopiedtomakeachangedversion.

TheactualdatastructureusedistheimmutableVectorclassfromtheScalacollectionslibrary.Theseare32-widehasharraymappedtries,asimplementedbyTiarkRompf,basedinpartonworkbyPhilBagwellandRichHickey.

http://en.wikipedia.org/wiki/Hash_array_mapped_trie

Math

AllnumbersinNetLogoarestoredinternallyasdoubleprecisionfloatingpointnumbers,asdefinedintheIEEE754standard.Theyare64bitnumbersconsistingofonesignbit,an11-bitexponent,anda52-bitmantissa.SeetheIEEE754standardfordetails.

An"integer"inNetLogoissimplyanumberthathappenstohavenofractionalpart.Nodistinctionismadebetween3and3.0;theyarethesamenumber.(Thisisthesameashowmostpeopleusenumbersineverydaycontexts,butdifferentfromsomeprogramminglanguages.Somelanguagestreatintegersandfloatingpointnumbersasdistincttypes.)

IntegersarealwaysprintedbyNetLogowithoutthetrailing".0":

show 1.5 + 1.5observer: 3

Ifanumberwithafractionalpartissuppliedinacontextwhereanintegerisexpected,thefractionalpartissimplydiscarded.Soforexample,crt 3.5createsthreeturtles;theextra0.5isignored.

Therangeofintegersis+/-9007199254740992(2^53,about9quadrillion).Calculationsthatexceedthisrangewillnotcauseruntimeerrors,butprecisionwillbelostwhentheleastsignificant(binary)digitsareroundedoffinorderfitthenumberinto64bits.Withverylargenumbers,thisroundingcanresultinimpreciseanswerswhichmaybesurprising:

show 2 ^ 60 + 1 = 2 ^ 60=> true

Calculationswithsmallernumberscanalsoproducesurprisingresultsiftheyinvolvefractionalquantities,sincenotallfractionscanbepreciselyrepresentedandroundoffmayoccur.Forexample:

show 1 / 6 + 1 / 6 + 1 / 6 + 1 / 6 + 1 / 6 + 1 / 6=> 0.9999999999999999show 1 / 9 + 1 / 9 + 1 / 9 + 1 / 9 + 1 / 9 + 1 / 9 + 1 / 9 + 1 / 9 + 1 / 9=> 1.0000000000000002

Anyoperationwhichproducesthespecialquantities"infinity"or"notanumber"willcausearuntimeerror.

Scientificnotation

VerylargeorverysmallfloatingpointnumbersaredisplayedbyNetLogousing"scientificnotation".Examples:

show 0.000000000001=> 1.0E-12show 50000000000000000000=> 5.0E19

NumbersinscientificnotationaredistinguishedbythepresenceoftheletterE(for"exponent").Itmeans"timestentothepowerof",soforexample,1.0E-12means1.0times10tothe-12power:

show 1.0 * 10 ^ -12=> 1.0E-12

YoucanalsousescientificnotationyourselfinNetLogocode:

show 3.0E6=> 3000000show 8.123456789E6=> 8123456.789show 8.123456789E7

=> 8.123456789E7show 3.0E16=> 3.0E16show 8.0E-3=> 0.0080show 8.0E-4=> 8.0E-4

Theseexamplesshowthatnumberswithfractionalpartsaredisplayedusingscientificnotationiftheexponentislessthan-3orgreaterthan6.NumbersoutsideofNetLogo'sintegerrangeof-9007199254740992to9007199254740992(+/-2^53)arealsoalwaysshowninscientificnotation:

show 2 ^ 60=> 1.15292150460684698E18

Whenenteringanumber,theletterEmaybeeitherupperorlowercase.Whenprintinganumber,NetLogoalwaysusesanuppercaseE:

show 4.5e20=> 4.5E20

Floatingpointaccuracy

BecausenumbersinNetLogoaresubjecttothelimitationsofhowfloatingpointnumbersarerepresentedinbinary,youmaygetanswersthatareslightlyinaccurate.Forexample:

show 0.1 + 0.1 + 0.1=> 0.30000000000000004show cos 90=> 6.123233995736766E-17

Thisisaninherentissuewithfloatingpointarithmetic;itoccursinallprogramminglanguagesthatusefloatingpointnumbers.

Ifyouaredealingwithfixedprecisionquantities,forexampledollarsandcents,acommontechniqueistouseonlyintegers(cents)internally,thendivideby100togetaresultindollarsfordisplay.

Ifyoumustusefloatingpointnumbers,theninsomesituationsyoumayneedtoreplaceastraightforwardequalitytestsuchasif x = 1 [ ... ]withatestthattoleratesslightimprecision,forexampleif abs (x - 1) < 0.0001 [ ... ] .

Also,theprecisionprimitiveishandyforroundingoffnumbersfordisplaypurposes.NetLogomonitorsroundthenumberstheydisplaytoaconfigurablenumberofdecimalplaces,too.

Randomnumbers

TherandomnumbersusedbyNetLogoarewhatiscalled"pseudo-random".(Thisistypicalincomputerprogramming.)Thatmeanstheyappearrandom,butareinfactgeneratedbyadeterministicprocess."Deterministic"meansthatyougetthesameresultseverytime,ifyoustartwiththesamerandom"seed".We'llexplaininaminutewhatwemeanby"seed".

Inthecontextofscientificmodeling,pseudo-randomnumbersareactuallydesirable.That'sbecauseit'simportantthatascientificexperimentbereproducible--soanyonecantryitthemselvesandgetthesameresultthatyougot.SinceNetLogousespseudo-randomnumbers,the"experiments"thatyoudowithitcanbereproducedbyothers.

Here'showitworks.NetLogo'srandomnumbergeneratorcanbestartedwithacertainseedvalue,whichmustbeanintegerintherange-2147483648to2147483647.Oncethegeneratorhasbeen"seeded"withtherandom-seedcommand,italwaysgeneratesthesamesequenceofrandomnumbersfromthenon.Forexample,ifyourunthesecommands:

random-seed 137

show random 100show random 100show random 100

Youwillalwaysgetthenumbers79,89,and61inthatorder.

Note,however,thatyou'reonlyguaranteedtogetthosesamenumbersifyou'reusingthesameversionofNetLogo.SometimeswhenwemakeanewversionofNetLogotherandomnumbergeneratorchanges.(Presently,weuseageneratorknownastheMersenneTwister.)

Tocreateanumbersuitableforseedingtherandomnumbergenerator,usethenew-seedreporter.new-seedcreatesaseed,evenlydistributedoverthespaceofpossibleseeds,basedonthecurrentdateandtime.Itneverreportsthesameseedtwiceinarow.

CodeExample:RandomSeedExample

Ifyoudon'tsettherandomseedyourself,NetLogosetsittoavaluebasedonthecurrentdateandtime.Thereisnowaytofindoutwhatrandomseeditchose,soifyouwantyourmodelruntobereproducible,youmustsettherandomseedyourselfaheadoftime.

TheNetLogoprimitiveswith"random"intheirnames(random,random-float,andsoon)aren'ttheonlyonesthatusepseudo-randomnumbers.Manyotheroperationsalsomakerandomchoices.Forexample,agentsetsarealwaysinrandomorder,one-ofandn-ofchooseagentsrandomly,thesproutcommandcreatesturtleswithrandomcolorsandheadings,andthedownhillreporterchoosesarandompatchwhenthere'satie.Alloftheserandomchoicesaregovernedbytherandomseedaswell,somodelrunscanbereproducible.

Inadditiontotheuniformlydistributedrandomintegersandfloatingpointnumbersgeneratedbyrandomandrandom-float,NetLogoalsooffersseveralotherrandomdistributions.Seethedictionaryentriesforrandom-normal,random-poisson,random-exponential,andrandom-gamma.

Auxiliarygenerator

Coderunbybuttonsorfromthecommandcenterusesthemainrandomnumbergenerator.

Codeinmonitorsusesanauxiliaryrandomgenerator,soevenifamonitordoesacalculationthatusesrandomnumbers,theoutcomeofthemodelisnotaffected.Thesameistrueofcodeinsliders.

Localrandomness

Youmaywanttoexplicitlyspecifythatasectionofcodedoesnotaffectthestateofthemainrandomgenerator,sotheoutcomeofthemodelisnotaffected.Thewith-local-randomnesscommandisprovidedforthispurpose.SeeitsentryintheNetLogoDictionaryformoreinformation.

Turtleshapes

InNetLogo,turtleshapesarevectorshapes.Theyarebuiltupfrombasicgeometricshapes;squares,circles,andlines,ratherthanagridofpixels.Vectorshapesarefullyscalableandrotatable.NetLogocachesbitmapimagesofvectorshapessize1,1.5,and2inordertospeedupexecution.

Aturtle'sshapeisstoredinitsshapevariableandcanbesetusingthesetcommand.

Newturtleshaveashapeof"default".Theset-default-shapeprimitiveisusefulforchangingthedefaultturtleshapetoadifferentshape,orhavingadifferentdefaultturtleshapeforeachbreedofturtle.

Theshapesprimitivereportsalistofcurrentlyavailableturtleshapesinthemodel.Thisisusefulif,forexample,youwanttoassignarandomshapetoaturtle:

ask turtles [ set shape one-of shapes ]

UsetheTurtleShapesEditortocreateyourownturtleshapes,ortoaddshapestoyourmodelfromourshapeslibrary,ortotransfershapesbetweenmodels.Formoreinformation,seetheShapesEditorsectionofthismanual.

Thethicknessofthelinesusedtodrawthevectorshapescanbecontrolledbythe__set-line-thicknessprimitive.

CodeExamples:BreedsandShapesExample,ShapeAnimationExample

Linkshapes

LinkShapesaresimilartoturtleshapes,onlyyouusetheLinkShapeEditortocreateandeditthem.Linkshapesconsistofbetween0and3lineswhichcanhavedifferentpatternsandadirectionindicatorthatiscomposedofthesameelementsasturtleshapes.Linksalsohaveashapevariablethatcanbesettoanylinkshapethatisinthemodel.Bydefaultlinkshavethe"default"shape,thoughyoucanchangethatusingset-default-shape.Thelink-shapesreporterreportsallthelinkshapesincludedinthecurrentmodel.

Thethicknessofthelinesinthelinkshapeiscontrolledbythethicknesslinkvariable.

Viewupdates

The"view"inNetLogoletsyouseetheagentsinyourmodelonyourcomputer'sscreen.Asyouragentsmoveandchange,youseethemmovingandchangingintheview.

Ofcourse,youcan'treallyseeyouragentsdirectly.TheviewisapicturethatNetLogopaints,showingyouhowyouragentslookataparticularinstant.Oncethatinstantpassesandyouragentsmoveandchangesomemore,thatpictureneedstoberepaintedtoreflectthenewstateoftheworld.Repaintingthepictureiscalled"updating"theview.

Whendoestheviewgetupdated?ThissectiondiscusseshowNetLogodecideswhentoupdatetheview,andhowyoucaninfluencewhenitgetsupdated.

NetLogoofferstwoupdatesmodes,"continuous"updatesand"tick-based"updates.YoucanswitchbetweenNetLogo'stwoviewupdatemodesusingapopupmenuatthetopoftheInterfacetab.

ContinuousupdatesarethedefaultwhenyoustartupNetLogoorstartanewmodel.NearlyeverymodelinourModelsLibrary,however,usestick-basedupdates.

Continuousupdatesaresimplest,buttick-basedupdatesgiveyoumorecontroloverwhenandhowoftenupdateshappen.

It'simportantexactlywhenanupdatehappens,becausewhenupdateshappendetermineswhatyouseeonthescreen.Ifanupdatecomesatanunexpectedtime,youmayseesomethingunexpected--perhapssomethingconfusingormisleading.

It'salsoimportanthowoftenupdateshappen,becauseupdatestaketime.ThemoretimeNetLogospendsupdatingtheview,thesloweryourmodelwillrun.Withfewerupdates,yourmodelrunsfaster.

Continuousupdates

Continuousupdatesareverysimple.Withcontinuousupdates,NetLogoupdatestheviewacertainnumberoftimespersecond--bydefault,30timesasecondwhenthespeedsliderisinthedefault,middlesetting.

Ifyoumovethespeedslidertoaslowersetting,NetLogowillupdatemorethan30timesasecond,effectivelyslowingdownthemodel.Onafastersetting,NetLogowillupdatelessthan30timesasecond.Onthefastestsetting,updateswillbeseparatedbyseveralseconds.

Atextremelyslowsettings,NetLogowillbeupdatingsooftenthatyouwillseeyouragentsmoving(orchangingcolor,etc.)oneatatime.

Ifyouneedtotemporarilyshutoffcontinuousupdates,usetheno-displaycommand.Thedisplaycommandturnsupdatesbackon,andalsoforcesanimmediateupdate(unlesstheuserisfast-forwardingthemodelusingthespeedslider).

Tick-basedupdates

AsdiscussedaboveintheTickCountersection,inmanyNetLogomodels,timepassesindiscretesteps,called"ticks".Typically,youwanttheviewtoupdateoncepertick,betweenticks.That'sthedefaultbehaviorwithtick-basedupdates.

Ifyouwantadditionalviewupdates,youcanforceanupdateusingthedisplaycommand.(Theupdatemaybeskippediftheuserisfast-forwardingthemodelusingthespeedslider.)

Youdon'thavetousethetickcountertousetick-basedupdates.Ifthetickcounterneveradvances,theviewwillupdateonlywhenyouusethedisplaycommand.

Ifyoumovethespeedslidertoafastenoughsetting,eventuallyNetLogowillskipsomeoftheupdatesthatwouldordinarilyhavehappened.Movingthespeedslidertoaslowersettingdoesn'tcauseadditionalupdates;rather,itmakesNetLogopauseaftereachupdate.Theslowerthesetting,thelongerthepause.

Evenundertick-basedupdates,theviewalsoupdateswheneverabuttonintheinterfacepopsup(bothonceandforeverbuttons)andwhenacommandenteredintheCommandCenterfinishes.Soit'snotnecessarytoaddthedisplaycommandtooncebuttonsthatdon'tadvancethetickcounter.Manyforeverbuttonsthatdon'tadvancethetickcounterdoneedtousethedisplaycommand.AnexampleintheModelsLibraryistheLifemodel(underComputerScience->CellularAutomata).Theforeverbuttonsthatlettheuserdrawintheviewusethedisplaycommandsotheusercanseewhattheyaredrawing,eventhoughthetickcounterisnotadvancing.

Choosingamode

Advantagesoftick-basedupdatesovercontinuousupdatesinclude:

1. Consistent,predictableviewupdatebehaviorwhichdoesnotvaryfromcomputertocomputerorfromruntorun.

2. Continuousupdatescanconfusetheuserofyourmodelbylettingthemseemodelstatestheyaren'tsupposedtosee,whichmaybemisleading.

3. Sincesetupbuttonsdon'tadvancethetickcounter,theyareunaffectedbythespeedslider;thisisnormallythedesiredbehavior.

NearlyeverymodelinourModelsLibraryusestick-basedupdates.

Continuousupdatesareoccasionallyusefulforthoseraremodelsinwhichexecutionisnotdividedintoshort,discretephases.AnexampleintheModelsLibraryisTermites.(Seealso,however,theStateMachineExamplemodel,whichshowshowtore-codeTermitesusingticks.)

Evenformodelsthatwouldnormallybesettotick-basedupdates,itmaybeusefultoswitchtocontinuousupdatestemporarilyfordebuggingpurposes.Seeingwhat'sgoingonwithinatick,insteadofonlyseeingtheendresultofatick,couldhelpwithtroubleshooting.Afterswitchingtocontinuousupdates,youmaywanttousethespeedslidertoslowthemodeldownuntilyouseeyouragentsmovingoneatatime.Don'tforgettochangebacktotick-basedupdateswhenyouaredone,asthechoiceofupdatemodeissavedwiththemodel.

Changingtheupdatemodealsoaffectsmodelspeed.Updatingtheviewtakestime;oftenenforcingasingleupdatepertick(byusingtick-basedupdates)willmakeyourmodelfaster.Ontheotherhand,continuousupdateswillbefasterwhenrunningasingletickisfasterthandrawingaframeofthemodel.Mostmodelsrunfasterundertick-basedupdates,butforanexampleofamodelwhichisfasterwithcontinuousupdatesseethe"HeroesandCowards"librarymodel.

Framerate

OneofthemodelsettingsinNetLogo's"Settings..."dialogis"Framerate"whichdefaultsto30framespersecond.

Theframeratesettingaffectsbothcontinuousupdatesandtick-basedupdates.

Withcontinuousupdates,thesettingdirectlydeterminesthefrequencyofupdates.

Withtick-basedupdates,thesettingisaceilingonhowmanyupdatespersecondyouget.Iftheframerateis30,thenNetLogowillensurethatthemodelneverrunsfasterthanthatwhenthespeedsliderisinthedefaultposition.Ifanyframetakeslessthan1/30ofasecondtocomputeanddisplay,NetLogowillpauseandwaituntilthefull1/30ofasecondhaspassedbeforecontinuing.

Theframeratesettingsletsyousetwhatyouconsidertobeanormalspeedforyourmodel.Thenyou,ortheuserofyourmodel,canusethespeedslidertotemporarilygetafasterorslowerspeed.

Plotting

NetLogo'splottingfeaturesletyoucreateplotstohelpyouunderstandwhat'sgoingoninyourmodel.

Beforeyoucanplot,youneedtocreateoneormoreplotsintheInterfacetab.FormoreinformationonusingandeditingplotsintheInterfacetab,seetheInterfaceGuide.

Plottingpoints

Thetwobasiccommandsforactuallyplottingthingsareplotandplotxy.

Withplotyouneedonlyspecifytheyvalueyouwantplotted.Thexvaluewillautomaticallybe0forthefirstpointyouplot,1forthesecond,andsoon.(That'siftheplotpen's"interval"isthedefaultvalueof1;youcanchangetheinterval.)

Theplotcommandisespeciallyhandywhenyouwantyourmodeltoplotanewpointateverytimestep.Example:

plot count turtles

Ifyouneedtospecifyboththexandyvaluesofthepointyouwantplotted,thenuseplotxyinstead.Thisexampleassumesthataglobalvariablecalledtimeexists:

plotxy time count-turtles

Plotcommands

Eachplotanditspenshavesetupandupdatecodefieldsthatmaycontaincommands(usuallycontainingplotorplotxy).ThesecommandsarerunautomaticallytriggeredbyothercommandsinNetLogo.

Plotsetupcommandsandpensetupcommandsarerunwhentheeitherreset-ticksorsetup-plotscommandsarerun.Ifthestopcommandisruninthebodyoftheplotsetupcommandsthenthepensetupcommandswillnotrun.

Plotupdatecommandsandpenupdatecommandsarerunwhentheeitherreset-ticks,tickorupdate-plotscommandsarerun.Ifthestopcommandisruninthebodyoftheplotupdatecommandsthenthepenupdatecommandswillnotrun.

Herearethefourcommandsthattriggerplottingexplainedinmoredetail.

setup-plotsexecutescommandsforoneplotatatime.Foreachplot,theplot'ssetupcommandsareexecuted.Ifthestopcommandisnotencounteredwhilerunningthosecommands,theneachoftheplot'spenswillhavetheirsetupcodeexecuted.update-plotsisverysimilartosetup-plots.Foreachplot,theplot'supdatecommandsareexecuted.Ifthestopcommandisnotencounteredwhilerunningthosecommands,theneachoftheplot'spenswillhavetheirupdatecodeexecuted.tickisexactlythesameasupdate-plotsexceptthatthetickcounterisincrementedbeforetheplotcommandsareexecuted.reset-ticksfirstresetsthetickcounterto0,andthendoestheequivalentofsetup-plotsfollowedbyupdate-plots.

Atypicalmodelwillusereset-ticksandticklikeso:

to setup clear-all ... reset-ticksend

to go ... tickend

Notethatinthisexampleweplotfromboththesetupandgoprocedures(becausereset-ticksrunsplotsetupandplotupdatecommands).Wedothisbecausewewantourplottoincludetheinitialstateofthesystemattheendofsetup.Weplotattheendofthegoprocedure,notthebeginning,becausewewanttheplotalwaystobeuptodateafterthegobuttonstops.

Modelsthatdon'tuseticksbutstillwanttodoplottingwillinsteadusesetup-plotsandupdate-plots.Inthepreviouscode,replacereset-tickswithsetup-plots update-plotsandreplacetickwithupdate-plots.

CodeExample:PlottingExample

Otherkindsofplots

Bydefault,NetLogoplotpensplotinlinemode,sothatthepointsyouplotareconnectedbyaline.

Ifyouwanttomovethepenwithoutplotting,youcanusetheplot-pen-upcommand.Afterthiscommandisissued,theplotandplotxycommandsmovethepenbutdonotactuallydrawanything.Oncethepeniswhereyouwantit,useplot-pen-downtoputthepenbackdown.

Ifyouwanttoplotindividualpointsinsteadoflines,oryouwanttodrawbarsinsteadoflinesorpoints,youneedtochangetheplotpen's"mode".Threemodesareavailable:line,bar,andpoint.Lineisthedefaultmode.

Normally,youchangeapen'smodebyeditingtheplot.Thischangesthepen'sdefaultmode.It'salsopossibletochangethepen'smodetemporarilyusingtheset-plot-pen-mode command.Thatcommandtakesanumberasinput:0forline,1forbar,2forpoint.

Histograms

Ahistogramisaspecialkindofplotthatmeasureshowfrequentlycertainvalues,orvaluesincertainranges,occurinacollectionofnumbersthatariseinyourmodel.

Forexample,supposetheturtlesinyourmodelhaveanagevariable.Youcouldcreateahistogramofthedistributionofagesamongyourturtleswiththehistogramcommand,likethis:

histogram [age] of turtles

Thenumbersyouwanttohistogramdon'thavetocomefromanagentset;theycouldbeanylistofnumbers.

Notethatusingthehistogramcommanddoesn'tautomaticallyswitchthecurrentplotpentobarmode.Ifyouwantbars,youhavetosettheplotpentobarmodeyourself.(Aswesaidbefore,youcanchangeapen'sdefaultmodebyeditingtheplotintheInterfacetab.)

Likeothertypesofplots,histogramscanbesettoautoscale.However,autoscaledhistogramsdonotautomaticallyresizethemselveshorizontallylikeotherplottypesdo.Tosettherangeprogrammatically,youcanusetheset-plot-x-rangeprimitive.

Thewidthofthebarsinahistogramiscontrolledbytheplotpen'sinterval.Youcansetaplotpen'sdefaultintervalbyeditingtheplotintheInterfacetab.Youcanalsochangetheintervaltemporarilywiththeset-plot-pen-intervalcommandortheset-histogram-num-bars.Ifyouusethelattercommand,NetLogowillsettheintervalappropriatelysoastofitthespecifiednumberofbarswithintheplot'scurrentxrange.

CodeExample:HistogramExample

Clearingandresetting

Youcanclearthecurrentplotwiththeclear-plotcommand,orcleareveryplotinyourmodelwithclear-all-plots.Theclear-all commandalsoclearsallplots,inadditiontoclearingeverythingelseinyourmodel.

Ifyouwanttoremoveonlythepointsthataparticularpenhasdrawn,useplot-pen-reset.

Whenawholeplotiscleared,orwhenapenisreset,thatdoesn'tjustremovethedatathathasbeenplotted.Italsorestorestheplotorpentoitsdefaultsettings,astheywerespecifiedintheInterfacetabwhentheplotwascreatedorlastedited.Therefore,theeffectsofsuchcommandsasset-plot-background-color,set-plot-x-range,andset-plot-pen-colorareonlytemporary.

Rangesandautoscaling

Thedefaultxandyrangesforaplotarefixednumbers,buttheycanbechangedatsetuptimeorasthemodelruns.

Tochangetherangesatanytime,useset-plot-x-rangeandset-plot-y-range.Or,youcanlettherangesgrowautomatically.Eitherway,whentheplotisclearedtherangeswillreturntotheirdefaultvalues.

Bydefault,allNetLogoplotshavetheautoscalingfeatureenabled.Thismeansthatifthemodeltriestoplotapointwhichisoutsidethecurrentdisplayedrange,therangeoftheplotwillgrowalongoneorbothaxessothatthenewpointisvisible.Histogramplots,however,donotautoscalehorizontally.

Inthehopethattherangeswon'thavetochangeeverytimeanewpointisadded,whentherangesgrowtheyleavesomeextraroom:25%ifgrowinghorizontally,10%ifgrowingvertically.

Ifyouwanttoturnoffthisfeature,edittheplotandunchecktheAutoScale?checkbox.Atpresent,itisnotpossibletoenableordisablethisfeatureonlyononeaxis;italwaysappliestobothaxes.

UsingaLegend

Youcanshowthelegendofaplotbycheckingthe"Showlegend"checkboxintheeditdialog.Ifyoudon'twantaparticularpentoshowupinthelegendyoucanuncheckthe"ShowinLegend"checkboxforthatpenalsointheadvancedplotpensettings(theadvancedplotpensettingscanbeopenedbyclickingthepencilbuttonforthatpenintheplotpenstableintheploteditdialog).

Temporaryplotpens

Mostplotscangetalongwithafixednumberofpens.Butsomeplotshavemorecomplexneeds;theymayneedtohavethenumberofpensvarydependingonconditions.Insuchcases,youcanmake"temporary"plotpensfromcodeandthenplotwiththem.Thesepensarecalled"temporary"becausetheyvanishwhentheplotiscleared(bytheclear-plot,clear-all-plots,orclear-allcommands).

Tocreateatemporaryplotpen,usethecreate-temporary-plot-pencommand.Typically,thiswouldbedoneintheCodetab,butitisalsopossibletousethiscommandfromplotsetuporplotupdatecode(intheeditdialog).Bydefault,thenewpenisdown,isblackincolor,hasanintervalof1,andplotsinlinemode.Commandsareavailabletochangeallofthesesettings;seethePlottingsectionoftheNetLogoDictionary.

Beforeyoucanusethepen,you'llhavetousetheusetheset-current-plotandset-current-plot-pencommands.Theseareexplainedinthenextsection.

set-current-plotandset-current-plot-pen

BeforeNetLogo5,itwasnotpossibletoputplotcommandsintheplotitself.AlloftheplotcodewaswrittenintheCodetabwiththerestofthecode.Forbackwardscompatibility,andfortemporaryplotpens,thisisstillsupported.ModelsinpreviousversionsofNetLogo(andthoseusingtemporaryplotpens)havetoexplicitlystatewhichplotisthecurrentplotwiththeset-current-plotcommandandwhichpenisthecurrentpenwiththeset-current-plot-pencommand.

Tosetthecurrentplotusetheset-current-plotcommandwiththenameoftheplotenclosedindoublequotes,likethis:

set-current-plot "Distance vs. Time"

Thenameoftheplotmustbeexactlyasyoutypeditwhenyoucreatedtheplot.Notethatlaterifyouchangethenameoftheplot,you'llalsohavetoupdatetheset-current-plotcallsinyourmodeltousethenewname.(Copyandpastecanbehelpfulhere.)

Foraplotwithmultiplepens,youcanmanuallyspecifywhichpenyouwanttoplotwith.Ifyoudon'tspecifyapen,plottingwilltakeplacewiththefirstpenintheplot.Toplotwithadifferentpen,theset-current-plot-pencommandwasusedwiththenameofthepenenclosedindoublequotes,likethis:

set-current-plot-pen "distance"

Oncethecurrentpenisset,thencommandslikeplot count turtlescanbeexecutedforthatpen.

Oldermodelswithplotsusuallyhadtheirowndo-plottingprocedurethatlookedsomethinglikethis:

to do-plotting set-current-plot "populations" set-current-plot-pen "sheep" plot count sheep set-current-plot-pen "wolves" plot count wolves

set-current-plot "next plot" ...end

Onceagain,thisisnolongernecessaryinNetLogo5,unlessyouareusingtemporaryplotpens.

Conclusion

NoteveryaspectofNetLogo'splottingsystemhasbeenexplainedhere.SeethePlottingsectionoftheNetLogoDictionaryforinformationonadditionalcommandsandreportersrelatedtoplotting.

ManyoftheSampleModelsintheModelsLibraryillustratevariousadvancedplottingtechniques.Alsocheckoutthefollowingcodeexamples:

CodeExamples:PlotAxisExample,PlotSmoothingExample,RollingPlotExample

Strings

StringsmaycontainanyUnicodecharacters.

ToinputaconstantstringinNetLogo,surrounditwithdoublequotes.

Theemptystringiswrittenbyputtingnothingbetweenthequotes,likethis:"".

Mostofthelistprimitivesworkonstringsaswell:

but-first "string" => "tring"but-last "string" => "strin"empty? "" => trueempty? "string" => falsefirst "string" => "s"item 2 "string" => "r"last "string" => "g"length "string" => 6member? "s" "string" => truemember? "rin" "string" => truemember? "ron" "string" => falseposition "s" "string" => 0position "rin" "string" => 2position "ron" "string" => falseremove "r" "string" => "sting"remove "s" "strings" => "tring"replace-item 3 "string" "o" => "strong"reverse "string" => "gnirts"

Afewprimitivesarespecifictostrings,suchasis-string?,substring,andword:

is-string? "string" => trueis-string? 37 => falsesubstring "string" 2 5 => "rin"word "tur" "tle" => "turtle"

Stringscanbecomparedusingthe=,!=,<,>,<=,and>=operators.

Ifyouneedtoembedaspecialcharacterinastring,usethefollowingescapesequences:

\n=newline\t=tab\"=doublequote\\=backslash

Output

Thissectionisaboutoutputtothescreen.Outputtothescreencanalsobelatersavedtoafileusingtheexport-outputcommand.Ifyouneedamoreflexiblemethodofwritingdatatoexternalfiles,seethenextsection,FileI/O.

ThebasiccommandsforgeneratingoutputtothescreeninNetLogoareprint,show,type,andwrite.ThesecommandssendtheiroutputtotheCommandCenter.

Forfulldetailsonthesefourcommands,seetheirentriesintheNetLogoDictionary.Hereishowtheyaretypicallyused:

printisusefulinmostsituations.showletsyouseewhichagentisprintingwhat.

typeletsyouprintseveralthingsonthesameline.writeletsyouprintvaluesinaformatwhichcanbereadbackinusingfile-read.

ANetLogomodelmayoptionallyhavean"outputarea"initsInterfacetab,separatefromtheCommandCenter.TosendoutputthereinsteadoftheCommandCenter,usetheoutput-print,output-show,output-type,andoutput-writecommands.

Theoutputareacanbeclearedwiththeclear-outputcommandandsavedtoafilewithexport-output.Thecontentsoftheoutputareawillbesavedbytheexport-worldcommand.Theimport-worldcommandwillcleartheoutputareaandsetitscontentstothevalueinimportedworldfile.Itshouldbenotedthatlargeamountsofdatabeingsenttotheoutputareacanincreasethesizeofyourexportedworlds.

Ifyouuseoutput-print,output-show,output-type,output-write,clear-output,orexport-outputinamodelwhichdoesnothaveaseparateoutputarea,thenthecommandsapplytotheoutputportionoftheCommandCenter.

FileI/O

InNetLogo,thereisasetofprimitivesthatgiveyouthepowertointeractwithoutsidefiles.Theyallbeginwiththeprefixfile-.

Therearetwomainmodeswhendealingwithfiles:readingandwriting.Thedifferenceisthedirectionoftheflowofdata.Whenyouarereadingininformationfromafile,datathatisstoredinthefileflowsintoyourmodel.Ontheotherhand,writingallowsdatatoflowoutofyourmodelandintoafile.

Whenworkingwithfiles,alwaysbeginbyusingtheprimitivefile-open.Thisspecifieswhichfileyouwillbeinteractingwith.Noneoftheotherprimitivesworkunlessyouopenafilefirst.

Thenextfile-primitiveyouusedictateswhichmodethefilewillbeinuntilthefileisclosed,readingorwriting.Toswitchmodes,closeandthenreopenthefile.

Thereadingprimitivesincludefile-read,file-read-line,file-read-characters,andfile-at-end?Notethatthefilemustexistalreadybeforeyoucanopenitforreading.

CodeExamples:FileInputExample

TheprimitivesforwritingaresimilartotheprimitivesthatprintthingsintheCommandCenter,exceptthattheoutputgetssavedtoafile.Theyincludefile-print,file-show,file-type,andfile-write.Notethatyoucannever"overwrite"data.Inotherwords,ifyouattempttowritetoafilewithexistingdata,allnewdatawillbeappendedtotheendofthefile.(Ifyouwanttooverwriteafile,usefile-deletetodeleteit,thenopenitforwriting.)

CodeExamples:FileOutputExample

Whenyouarefinishedusingafile,youcanusethecommandfile-closetoendyoursessionwiththefile.Ifyouwishtoremovethefileafterwards,usetheprimitivefile-deletetodeleteit.Toclosemultipleopenedfiles,oneneedstofirstselectthefilebyusingfile-openbeforeclosingit.

;; Open 3 filesfile-open "myfile1.txt"file-open "myfile2.txt"file-open "myfile3.txt"

;; Now close the 3 filesfile-closefile-open "myfile2.txt"file-closefile-open "myfile1.txt"file-close

Or,ifyouknowyoujustwanttocloseeveryfile,youcanusefile-close-all.

Twoprimitivesworthnotingarefile-writeandfile-read.TheseprimitivesaredesignedtoeasilysaveandretrieveNetLogoconstantssuchasnumbers,lists,booleans,andstrings.file-writewillalwaysoutputthevariableinsuchamannerthatfile-readwillbeabletointerpretitcorrectly.

file-open "myfile.txt" ;; Opening file for writingask turtles [ file-write xcor file-write ycor ]file-close

file-open "myfile.txt" ;; Opening file for readingask turtles [ setxy file-read file-read ]file-close

CodeExamples:FileInputExampleandFileOutputExample

Lettingtheuserchoose

Theuser-directory,user-file,anduser-new-fileprimitivesareusefulwhenyouwanttheusertochooseafileordirectoryforyourcodetooperateon.

Movies

Thissectiondescribeshowtocapturean".mp4"movieofaNetLogomodel.

First,usethevid:start-recordercommandtostartthevideorecorder.

Toaddaframetoyourmovie,useeithervid:record-vieworvid:record-interface,dependingonwhetheryouwantthemovietoshowjustthecurrentview,ortheentireInterfacetab.Inasinglemovie,theresolutionwillbeoneofthefollowing:

theresolutionspecifiedinthecalltovid:start-recorder width heightifyouspecifiedtheresolution.Theseareoptionalparameters.Theresolutionoftheviewifyoudidnotspecifyaresolutioninthecalltovid:start-recorderandcallvid:record-viewbeforecallingvid:record-interfaceTheresolutionoftheinterfaceifyoudidnotspecifyaresolutioninthecalltovid:start-recorderandcallvid:record-interfacebeforecallingvid:record-view

Notethatiftheresolutionofarecordedimagedoesn'tmatchtheresolutionoftherecordingitwillbescaledtofitwhichcanresultinimageswhichlookblurryorout-of-focus.

Whenyou'redoneaddingframes,usevid:save-recording.Thefilenameyouprovideshouldendwith.mp4,theextensionforMP4-encodedmovies(playableinQuickTimeandotherprograms).

;; export a 30 frame movie of the viewextensions [vid]

;...

setupvid:start-recordervid:record-view ;; show the initial staterepeat 30[ go vid:record-view ]vid:save-recording "out.mp4"

Amoviewillplaybackat25framespersecond.Tomakethemovieplaybackfasterorslower,considerusingavideopostprocessingtool.

Tocheckwhetherornotyouarerecording,callvid:recorder-status,whichreportsastringthatdescribesthestateofthecurrentrecorder.

Tothrowawaythemoviecurrentlybeingrecorded,callvid:reset-recorder.

CodeExample:MovieExample

Moviesgeneratedwhenrunningheadless,orbybackgroundrunsinaparallelBehaviorSpaceexperimentmayuseonlyvid:record-viewprimitive.MoviesgeneratedinNetLogoGUImayalsousevid:record-interfaceandvid:record-source.

NetLogomoviesareexportedasH.264-encodedMP4files.ToplayanMP4movie,youcanusetheVLCPlayer,afreedownloadfromtheVideoLANorganization.

Moviescantakeupalotofdiskspace.Youwillprobablywanttocompressyourmovieswiththird-partysoftware.Thesoftwaremaygiveyouachoiceofdifferentkindsofcompression.Somekindsofcompressionarelossless,whileothersarelossy."Lossy"meansthatinordertomakethefilessmaller,someofthedetailinthemovieislost.Dependingonthenatureofyourmodel,youmaywanttoavoidusinglossycompression,forexampleiftheviewcontainsfinepixel-leveldetail.

Perspective

The2Dandthe3Dviewshowtheworldfromtheperspectiveoftheobserver.Bydefaulttheobserverislookingdownontheworldfromthepositivez-axisattheorigin.Youcanchangetheperspectiveoftheobserverbyusingthefollow,rideandwatchobservercommandsandfollow-me,ride-meandwatch-meturtlecommands.Wheninfolloworridemodetheobservermoveswiththesubjectagentaroundtheworld.Thedifferencebetweenfollowandrideisonlyvisibleinthe3Dview.Inthe3Dviewtheusercanchangethedistancebehindtheagentusingthemouse.Whentheobserverisfollowingatzerodistancefromtheagentitisactuallyridingtheagent.Whentheobserverisinwatchmodeittracksthemovementsofoneturtlewithoutmoving.Inbothviewsyouwillseeaspotlightappearonthesubjectandinthe3Dviewtheobserverwillturntofacethesubject.Todeterminewhichagentisthefocusyoucanusethesubjectreporter.

CodeExample:PerspectiveExample

Drawing

Thedrawingisalayerwhereturtlescanmakevisiblemarks.

Intheview,thedrawingappearsontopofthepatchesbutunderneaththeturtles.Initially,thedrawingisemptyandtransparent.

Youcanseethedrawing,buttheturtles(andpatches)can't.Theycan'tsensethedrawingorreacttoit.Thedrawingisjustforpeopletolookat.

Turtlescandrawanderaselinesinthedrawingusingthepen-downandpen-erasecommands.Whenaturtle'spenisdown(orerasing),theturtledraws(orerases)alinebehinditwheneveritmoves.Thelinesarethesamecolorastheturtle.Tostopdrawing(orerasing),usepen-up.

Linesdrawnbyturtlesarenormallyonepixelthick.Ifyouwantadifferentthickness,setthepen-sizeturtlevariabletoadifferentnumberbeforedrawing(orerasing).Innewturtles,thevariableissetto1.

Linesmadewhenaturtlemovesinawaythatdoesn'tfixadirection,suchaswithsetxyormove-to,theshortestpathlinethatobeysthetopologywillbedrawn.

Here'ssometurtleswhichhavemadeadrawingoveragridofrandomlyshadedpatches.Noticehowtheturtlescoverthelinesandthelinescoverthepatchcolors.Thepen-sizeusedherewas2:

http://www.videolan.org/vlc/index.html

Thestampcommandletsaturtleleaveanimageofitselfbehindinthedrawingandstamp-eraseletsitremovethepixelsbelowitinthedrawing.

Toerasethewholedrawing,usetheobservercommmandclear-drawing.(Youcanalsouseclear-all,whichclearseverythingelsetoo.)

Importinganimage

Theobservercommandimport-drawingcommandallowsyoutoimportanimagefilefromdiskintothedrawing.

import-drawingisusefulonlyforprovidingabackdropforpeopletolookat.Ifyouwantturtlesandpatchestoreacttotheimage,youshoulduseimport-pcolorsorimport-pcolors-rgbinstead.

ComparisontootherLogos

DrawingworkssomewhatdifferentlyinNetLogothansomeotherLogos.

Notabledifferencesinclude:

Newturtles'pensareup,notdown.Insteadofusingafencecommandtoconfinetheturtleinsideboundaries,inNetLogoyouedittheworldandturnwrappingoff.Thereisnoscreen-color,bgcolor,orsetbg.Youcanmakeasolidbackgroundbycoloringthepatches,e.g.ask patches [ set pcolor blue ] .

DrawingfeaturesnotsupportedbyNetLogo:

Thereisnowindowcommand.ThisisusedinsomeotherLogostolettheturtleroamoveraninfiniteplane.Thereisnofloodorfillcommandtofillanenclosedareawithcolor.

Topology

Thewaytheworldofpatchesisconnectedcanchange.Bydefaulttheworldisatoruswhichmeansitisn'tbounded,but"wraps"--sowhenaturtlemovespasttheedgeoftheworld,itdisappearsandreappearsontheoppositeedgeandeverypatchhasthesamenumberof"neighbor"patches.Ifyou'reapatchontheedgeoftheworld,someofyour"neighbors"areontheoppositeedge.

However,youcanchangethewrapsettingswiththeSettingsbutton.Ifwrappingisnotallowedinagivendirectiontheninthatdirection(xory)theworldisbounded.Patchesalongthatboundarywillhavefewerthan8neighborsandturtleswillnotmovebeyondtheedgeoftheworld.

ThetopologyoftheNetLogoworldhasfourpotentialvalues,torus,box,verticalcylinder,orhorizontalcylinder.Thetopologyiscontrolledbyenablingordisablingwrappinginthexorydirections.Thedefaultworldisatorus.

Atoruswrapsinbothdirections,meaningthatthetopandbottomedgesoftheworldareconnectedand

theleftandrightedgesareconnected.Soifaturtlemovesbeyondtherightedgeoftheworlditappearsagainontheleftandthesameforthetopandbottom.

Aboxdoesnotwrapineitherdirection.Theworldisboundedsoturtlesthattrytomoveofftheedgeoftheworldcannot.Notethatthepatchesaroundedgeoftheworldhavefewerthaneightneighbors;thecornershavethreeandtheresthavefive.

Horizontalandverticalcylinderswrapinonedirectionbutnottheother.Ahorizontalcylinderwrapsvertically,sothetopoftheworldisconnectedtothebottom.buttheleftandrightedgesarebounded.Averticalcylinderistheopposite;itwrapshorizontallysotheleftandrightedgesareconnected,butthetopandbottomedgesarebounded.

CodeExample:NeighborsExample

Whencoordinateswrap,turtlesandlinkswrapvisuallyintheview,too.Ifaturtleshapeorlinkextendspastanedge,partofitwillappearattheotheredge.(Turtlesthemselvesarepointsthattakeupnospace,sotheycannotbeonbothsidesoftheworldatonce,butintheview,theyappeartotakeupspacebecausetheyhaveashape.)

Wrappingalsoaffectshowtheviewlookswhenyouarefollowingaturtle.Onatorus,wherevertheturtlegoes,youwillalwaysseethewholeworldaroundit:

Whereasinaboxorcylindertheworldhasedges,sotheareaspastthoseedgesshowupintheviewasgray:

CodeExample:TermitesPerspectiveDemo(torus),AntsPerspectiveDemo(box)

Thetopologysettingsalsocontrolthebehaviorofthedistance(xy),in-radius,in-cone,face(xy),andtowards(xy)primitives.Thetopologycontrolswhethertheprimitiveswrapornot.Theyalwaysusetheshortestpathallowedbythetopology.Forexample,thedistancefromthecenterofthepatchesinthebottomrightcorner(min-pxcor,min-pycor)andtheupperleftcorner(max-pxcor,max-pycor)willbeasfollowsforeachtopologygiventhattheminandmaxpxcorandpycorare+/-2:

Torus-sqrt(2)~1.414(thiswillbethesameforallworldsizessincethepatchesaredirectlydiagonaltoeachotherinatorus.)Box-sqrt(world-width^2+world-height^2)~7.07VerticalCylinder-sqrt(world-height^2+1)~5.099HorizontalCylinder-sqrt(world-width^2+1)~5.099

Alltheotherprimitiveswillactsimilarlytodistance.Ifyouformerlyused-nowrapprimitivesinyourmodelwerecommendremovingthemandchangingthetopologyoftheworldinstead.

Ifyourmodelhasturtlesthatmovearoundyou'llneedtothinkaboutwhathappenstothemwhentheyreachtheedgeoftheworld,ifthetopologyyou'reusinghassomenon-wrappingedges.Thereareafewcommonoptions:theturtleisreflectedbackintotheworld(eithersystematicallyorrandomly),theturtleexitsthesystem(dies),ortheturtleishidden.Itisnolongernecessarytochecktheboundsusingturtlecoordinates,insteadwecanjustaskNetLogoifaturtleisattheedgeoftheworld.Thereareacouplewaysofdoingthis,thesimplestistousethecan-move?primitive.

if not can-move? distance [ rt 180 ]

can-move?merelyreturnstrueifthepositiondistanceinfrontoftheturtleisinsidetheNetLogoworld,falseotherwise.Inthiscase,iftheturtleisattheedgeoftheworlditsimplegoesbackthewayitcame.Youcanalsousepatch-ahead 1 != nobodyinplaceofcan-move?.Ifyouneedtodosomethingsmarterthatsimplyturningarounditmaybeusefultousepatch-atwithdxanddy.

if patch-at dx 0 = nobody [ set heading (- heading)]if patch-at 0 dy = nobody [ set heading (180 - heading)]

Thistestswhethertheturtleishittingahorizontalorverticalwallandbouncesoffthatwall.

Insomemodelsifaturtlecan'tmoveforwarditsimplydies(exitsthesystem,likeinConductororMousetraps).

if not can-move? distance[ die ]

Ifyouaremovingturtlesusingsetxyratherthanforwardyoushouldtesttomakesurethepatchyouareabouttomovetoexistssincesetxythrowsaruntimeerrorifitisgivencoordinatesoutsidetheworld.Thisisacommonsituationwhenthemodelissimulatinganinfiniteplaneandturtlesoutsidetheviewshouldsimplybehidden.

let new-x new-value-of-xcorlet new-y new-value-of-ycor

ifelse patch-at (new-x - xcor) (new-y - ycor) = nobody [ hide-turtle ] [ setxy new-x new-y show-turtle ]

SeveralmodelsintheModelsLibraryusethistechnique,Gravitation,N-Bodies,andElectrostaticsaregoodexamples.

Thediffuseanddiffuse4commandsbehavecorrectlyinalltopologies.Eachpatchdiffusesandequalamountofthediffusevariabletoeachofitsneighbors,ifithasfewerthan8neighbors(or4ifyouareusingdiffuse4),theremainderstaysonthediffusingpatch.Thismeansthattheoverallsumofpatch-variableacrosstheworldremainsconstant.However,ifyouwantthediffusemattertostillfallofftheedgesoftheworldasitwouldonaninfiniteplaneyoustillneedtocleartheedgeseachstepasintheDiffuseOffEdgesExample.

Links

Alinkisanagentthatconnectstwoturtles.Theseturtlesaresometimesalsocallednodes.

Thelinkisalwaysdrawnasalinebetweenthetwoturtles.Linksdonothavealocationasturtlesdo,theyarenotconsideredtobeonanypatchandyoucannotfindthedistancefromalinktoanotherpoint.

Therearetwolinkdesignations:undirectedanddirected.Adirectedlinkisoutof,orfrom,onenodeandinto,orto,anothernode.Therelationshipofaparenttoachildcouldbemodeledasadirectedlink.Anundirectedlinkappearsthesametobothnodes,eachnodehasalinkwithanothernode.Therelationshipbetweenspouses,orsiblings,couldbemodeledasanundirectedlink.

Thereisaglobalagentsetofalllinks,justaswithturtlesandpatches.Youcancreateundirectedlinksusingthecreate-link-withandcreate-links-withcommands;anddirectedlinksusingthecreate-link-to,create-links-to,create-link-from,andcreate-links-fromcommands.Oncethefirstlinkhasbeencreateddirectedorundirected,allunbreededlinksmustmatch(linksalsosupportbreeds,muchliketurtles,whichwillbediscussedshortly);it'simpossibletohavetwounbreededlinkswhereoneisdirectedandtheotherisundirected.Aruntimeerroroccursifyoutrytodoit.(Ifallunbreededlinksdie,thenyoucancreatelinksofthatbreedthataredifferentindesignationfromthepreviouslinks.)

Ingeneral,linkprimitivenamesindicatewhatkindoflinkstheydealwith:

Primitivesthathave"out"intheirnameutilizeoutgoingandundirectedlinks.Youcanthinkoftheseas"thelinksIcanusetogetfromthecurrentnodetoothernodes."Ingeneral,theseareprobablytheprimitivesyouwanttouse.Primitivesthathave"in"intheirnameutilizeincomingandundirectedlinks.Youcanthinkoftheseas"thelinksIcanusetogettothecurrentnodefromothernodes."Primtivesthatdonotspecify"in"or"out",orhave"with"intheirnameutilizealllinks,bothundirectedanddirected,incomingandoutgoing.

Alink'send1andend2variablescontainthetwoturtlesthelinkconnects.Ifthelinkisdirected,itgoesfromend1toend2.Ifthelinkisundirected,end1isalwaystheolderofthetwoturtles,thatis,theturtlewiththesmallerwhonumber.

Linkbreeds,liketurtlebreeds,allowyoutodefinedifferenttypesoflinksinyourmodel.Linkbreedsmusteitherbedirectedorundirected,unlikeunbreededlinksthisisdefinedatcompiletimeratherthanruntime.Youdeclarelinkbreedsusingthekeywordsundirected-link-breedanddirected-link-breed.Breededlinkscanbecreatedusingthecommandscreate-<breed>-withandcreate-<breeds>-withforundirectedbreedsandthecommandscreate-<breed>-to,create-<breeds>-to,create-<breed>-from,andcreate-<breeds>-fromfordirectedlinks.

Therecannotbemorethanoneundirectedlinkofthesamebreed(ormorethanoneunbreededundirectedlink)betweenapairofagents,normorethanonedirectedlinkofthesamebreedinthesamedirectionbetweenapairofagents.Youcanhavetwodirectedlinksofthesamebreed(ortwounbreededdirectedlinks)betweenapairiftheyareinoppositedirections.

Layouts

Aspartofournetworksupportwehavealsoaddedseveraldifferentprimitivesthatwillhelpyoutovisualizethenetworks.Thesimplestislayout-circlewhichevenlyspacestheagentsaroundthecenteroftheworldgivenaradius.

layout-radialisagoodlayoutifyouhavesomethinglikeatreestructure,thougheveniftherearesomecyclesinthetreeitwillstillwork,thoughastherearemoreandmorecyclesitwillprobablynotlookasgood.layout-radialtakesarootagenttobethecentralnodeplacesitat(0,0)andarrangesthenodesconnectedtoitinaconcentricpattern.Nodesonedegreeawayfromtherootwillbearrangedinacircularpatternaroundthecentralnodeandthenextlevelaroundthosenodesandsoon.layout-radialwillattempttoaccountforasymmetricalgraphsandgivemorespacetobranchesthatarewider.layout-radialalsotakesabreedasaninputsoyouuseonebreedoflinkstolayoutthenetworkandnotanother.

Givenasetofanchornodeslayout-tutteplacesalltheothernodesatthecenterofmassofthenodesitislinkedto.Theanchorsetisautomaticallyarrangedinacirclelayoutwithauserdefinedradiusandtheothernodeswillconvergeintoplace(thisofcoursemeansthatyoumayhavetorunitseveraltimesbeforethelayoutisstable.)

layout-springisusefulformanykindsofnetworks.Thedrawbackisthatisrelativelyslowsinceittakesmanyiterationstoconverge.Inthislayoutthelinksactasspringsthatpullthenodestheyconnecttowardeachotherandthenodesrepeleachother.Thestrengthoftheforcesiscontrolledbyinputstotheprimitives.Theseinputswillalwayshaveavaluebetween0and1;keepinmindthatverysmallchangescanstillaffecttheappearanceofthenetwork.Thespringsalsohavealength(inpatchunits),

however,becauseofalltheforcesinvolvedthenodeswillnotendupexactlythatdistancefromeachother.

CodeExamples:NetworkExample,NetworkImportExample,GiantComponent,SmallWorlds,PreferentialAttachment

Anonymousprocedures

Anonymousproceduresletyoustorecodetoberunlater.JustlikeregularNetLogoprocedures,ananonymousprocedurescanbeeitheracommand(anonymouscommand)orareporter(anonymousreporter).

Anonymousproceduresarevalues,whichmeanstheymaybepassedasinput,reportedasaresult,orstoredinavariable.

Ananonymousproceduremightberunonce,multipletimes,ornotatall.

Inotherprogramminglanguagesanonymousproceduresareknownasfirst-classfunctions,closures,orlambda.

Anonymousprocedureprimitives

Primitivesspecifictoanonymousproceduresare->,is-anonymous-command?,andis-anonymous-reporter?.

The->createsananonymousprocedure.Theanonymousprocedureitreportsmightbeacommandorareporter,dependingonwhatkindofblockyoupassit.Forexample[ -> fd 1 ] reportsananonymouscommand,becausefdisacommand,while[ -> count turtles ] reportsananonymousreporter,becausecountisareporter.

Theseprimitivesrequireanonymousproceduresasinput:foreach,map,reduce,filter,n-values,sort-by.Whencallingtheseprimitives,usingan->isoptionalifyouranonymousprocedurecontainsasingleprimitivewhichhasrequiresnomoreinputsthanareareprovidedbytheprimitive.Forexampleonemaywritesimplyforeach mylist printinsteadofforeach mylist [ [x] -> print x ] ,thoughthelatterisalsoaccepted.Dependingontheanonymousprocedure,variouspartsoftheanonymousproceduresyntaxcanbeomitted.Forasummaryofoptionalsyntax,seethetablebelow.

Theruncommandacceptsanonymouscommandsaswellasstrings.

Therunresultreporteracceptsanonymousreportersaswellasstrings.

runandrunresultallowpassinginputstoananonymousprocedure.Aswithallprimitivesacceptingvaryingnumberofinputs,thewholecallmustbesurroundedwithparentheses,soforexample(run my-anonymous-command 5)or(runresult my-anonymous-reporter "foo" 2).Whennotpassinginput,noparenthesesarerequired.

Anonymousprocedureinputs

Ananonymousproceduremaytakezeroormoreinputs.Theinputsarereferencedthevariablesdeclaredbeforethearrow.Forinstance,intheanonymousreporter[ [a b] -> a + b ] ,aandbareinputs.

Anonymousproceduresandstrings

Creatingandrunninganonymousproceduresisfast.Touserunorrunresultonanewstringforthefirsttimeisabout100xslowerthanrunningananonymousprocedure.Modelersshouldnormallyuseanonymousproceduresinsteadofrunningstrings,exceptwhenrunningstringsenteredbytheuser.

Concisesyntax

Simpleusesofforeach,map,reduce,filter,n-values,andsort-bycanbewrittenwithanespeciallyconcisesyntax.Youcanwrite:

map abs [1 -2 3 -4];; => [1 2 3 4]reduce + [1 2 3 4];; => 10filter is-number? [1 "x" 3];; => [1 3]foreach [1 2 3 4] print;; prints 1 through 4

InolderNetLogoversions(4andearlier),thesehadtobewritten:

map [abs ?] [1 -2 3 -4];; => [1 2 3 4]reduce [?1 + ?2] [1 2 3 4];; => 10filter [is-number? ?] [1 "x" 3];; => [1 3]foreach [1 2 3 4] [ print ? ];; prints 1 through 4

Anonymousproceduresasclosures

Anonymousproceduresare"closures";thatmeanstheycaptureor"closeover"thebindings(notjustthecurrentvalues)oflocalvariablesandprocedureinputs.Theydonotcaptureagentvariablesanddonotcapturetheidentity(oreventheagenttype)ofthecurrentagent.

Nonlocalexits

Thestopandreportcommandsexitfromthedynamicallyenclosingprocedure,nottheenclosinganonymousprocedure.(Thisisbackward-compatiblewitholderNetLogoversions.)

Anonymousproceduresandextensions

TheextensionsAPIsupportswritingprimitivesthatacceptanonymousproceduresasinput.Writeusforsamplecode.

Limitations

WehopetoaddressatleastsomeofthefollowinglimitationsinfutureNetLogoversions:

import-worlddoesnotsupportanonymousprocedures.Anonymousprocedurescan'tbevariadic(acceptavaryingnumberofinputs).Anonymousreporterscan'tcontaincommands,onlyasinglereporterexpression.Soforexampleyoumustuseifelse-valuenotif,andyoudon'tusereportatall.Ifyourcodeistoocomplextobewrittenasonereporter,you'llneedtomovethecodetoaseparatereporterprocedure,andthencallthatprocedurefromyouranonymousreporter,passingitanyneededinputs.Anonymousproceduresarenotinterchangeablewithcommandblocksandreporterblocks.Onlytheprimitiveslistedaboveacceptanonymousproceduresasinput.Controlprimitivessuchasifelseandwhileandagentprimitivessuchasofandwithdon'tacceptanonymousprocedures.SoforexampleifIhaveananonymousreporterlet r [ -> if random 2 == 0 ] andtwoanonymouscommandslet c1 [ -> tick ] andlet c2 [ -> stop ] ,Ican'twriteifelse r c1 c2,Imustwriteifelse runresult r [ run c1 ] [ run c2 ].Theconcisesyntaxwhere->maybeomittedisonlyavailabletoprimitivesandextensionprimitives,notordinaryprocedures.SoforexampleifIhaveaprocedurepthatacceptsananonymousprocedureasinput,itmustbecalledase.g.p [ -> ... ]notp [ ... ].

WhatisOptional?

Thereareseveraldifferentwaysofwritinganonymousprocedureswhichallowuserstoomitpartoralloftheanonymousproceduresyntax.Thesearesummarizedinthetablebelow.

Whatistheanonymousprocedurelike?

Whatcanbeleftout? Examples

Theanonymousprocedureisasingleprimitive

inputnamesarrowblockbrackets

foreach mylist stamp ; no inputsforeach mylist print ; single input(foreach xs ys setxy) ; multipleinputsmap round [1.3 2.4 3.5] ; reporter,single input(map + [1 2 3] [4 5 6]) ; reporter,multiple inputs

Theanonymousproceduretakesnoinputs

inputnamesarrow

foreach mylist [ print "abc" ]map [ 4 ] mylist

Theanonymousprocedurehaszerooroneinput(s)

bracketsaroundinputnames

foreach mylist [ -> stamp ] ; noinputsforeach mylist [ x -> print x ] ;single inputforeach mylist [ x -> rt x fd x ] ;multiple primitives, single inputmap [ -> world-width ] mylist ;reporter, no inputsmap [ x -> x ^ 2 ] mylist ; reporter,single input

Anonymousproceduretakesmorethanoneinput nothing

(foreach xs ys [ [ x y ] -> setx x +y ])(map [ [ x y ] -> x mod round y ] xsys)

Note:bracketsaroundinputnameswerealwaysrequiredinNetLogo6.0.0.IfyoucopyandpastecodeintoNetLogo6.0.0usinganonymousprocedureswithunbracketedinputnames,thecodewillnotcompileuntilyouaddthebrackets.

Codeexample

CodeExample:StateMachineExample

Ask-Concurrent

NOTE:Thefollowinginformationisincludedonlyforbackwardscompatibility.Wedon'trecommendusingtheask-concurrentprimitiveatallinnewmodels.

InveryoldversionsofNetLogo,askhadsimulatedconcurrentbehaviorbydefault.SinceNetLogo4.0(2007),askisserial,thatis,theagentsrunthecommandsinsidetheaskoneatatime.

Thefollowinginformationdescribesthebehavioroftheask-concurrentcommand,whichbehavesthewaytheoldaskbehaved.

ask-concurrentproducessimulatedconcurrencyviaamechanismofturn-taking.Thefirstagenttakesaturn,thenthesecondagenttakesaturn,andsoonuntileveryagentintheaskedagentsethashadaturn.Thenwegobacktothefirstagent.Thiscontinuesuntilalloftheagentshavefinishedrunningallofthecommands.

Anagent's"turn"endswhenitperformsanactionthataffectsthestateoftheworld,suchasmoving,orcreatingaturtle,orchangingthevalueofaglobal,turtle,patch,orlinkvariable.(Settingalocalvariabledoesn'tcount.)

Theforward(fd)andback(bk)commandsaretreatedspecially.Whenusedinsideask-concurrent,thesecommandscantakemultipleturnstoexecute.Duringitsturn,theturtlecanonlymovebyonestep.Thus,forexample,fd 20isequivalenttorepeat 20 [ fd 1 ] ,wheretheturtle'sturnendsaftereachrunoffd.Ifthedistancespecifiedisn'taninteger,thelastfractionofsteptakesafullturn.Soforexamplefd 20.3isequivalenttorepeat 20 [ fd 1 ] fd 0.3.

Thejumpcommandalwaystakesexactlyoneturn,regardlessofdistance.

Tounderstandthedifferencebetweenaskandask-concurrent,considerthefollowingtwocommands:

ask turtles [ fd 5 ]ask-concurrent turtles [ fd 5 ]

Withask,thefirstturtletakesfivestepsforward,thenthesecondturtletakesfivestepsforward,andsoon.

Withask-concurrent,alloftheturtlestakeonestepforward.Thentheyalltakeasecondstep,andsoon.Thus,thelattercommandisequivalentto:

repeat 5 [ ask turtles [ fd 1 ] ]

CodeExample:Ask-ConcurrentExampleshowsthedifferencebetweenaskandask-concurrent.

Thebehaviorofask-concurrentcannotalwaysbesosimplyreproducedusingask,asinthisexample.Considerthiscommand:

ask-concurrent turtles [ fd random 10 ]

Inordertogetthesamebehaviorusingask,wewouldhavetowrite:

turtles-own [steps]ask turtles [ set steps random 10 ]while [any? turtles with [steps > 0]] [ ask turtles with [steps > 0] [ fd 1 set steps steps - 1 ]]

Toprolonganagent's"turn",usethewithout-interruptioncommand.(Thecommandblocksinsidesomecommands,suchascreate-turtlesandhatch,haveanimpliedwithout-interruptionaroundthem.)

Notethatthebehaviorofask-concurrentiscompletelydeterministic.Giventhesamecodeandthesameinitialconditions,thesamethingwillalwayshappen(ifyouareusingthesameversionofNetLogoandbeginyourmodelrunwiththesamerandomseed).

Ingeneral,wesuggestyounotuseask-concurrentatall.Ifyoudo,wesuggestyouwriteyourmodelsothatitdoesnotdependontheexactdetailsofhowask-concurrentworks.WemakenoguaranteesthatitssemanticswillremainthesameinfutureversionsofNetLogo,orthatitwillcontinuetobesupported

atall.

UserInteractionPrimitives

NetLogofeaturesseveralprimitiveswhichallowamodeltointeractwiththeuser.Theseprimitivesincludeuser-directory,user-file,user-new-file,user-input,user-message,user-one-of,anduser-yes-or-no?.

Theseprimitivesdifferinpreciselywhatinteractiontheytakewiththeuser.user-directory,user-file,anduser-new-fileareallreporterswhichprompttheusertoselectanitemfromthefilesystemandreportthepathoftheselecteditemtoNetLogo.user-yes-or-no?,user-one-of,anduser-inputallprompttheusertoprovideinputintheformoftextoraselection.user-messagesimplypresentsamessagetotheuser.

Notethatallactiveforeverbuttonswillpausewhenoneoftheseprimitivesisusedandwillresumeonlywhentheusercompletestheinteractionwiththebutton.

Whatdoes"Halt"mean?

Theprimitiveswhichprompttheuserforinput,aswellasuser-messageallprovidea"Halt"button.Theeffectofthisbuttonisthesameforalloftheseprimitives-ithaltsthemodel.Whenthemodelishaltedallrunningcodeisstopped,includingbuttonsandthecommandcenter.Sincehaltingstopscodeinthemiddleofwhateverithappenedtobedoingatthetimeitwashalted,youmayseestrangeresultsifyoucontinuetorunthemodelafterahaltwithoutsettingitupagain.

Tie

Tieconnectstwoturtlessothatthemovementofoneturtlesaffectsthelocationandheadingofanother.Tieisapropertyoflinkssotheremustbealinkbetweentwoturtlestocreateatierelationship.

Whenalink'stie-modeissetto"fixed"or"free"end1andend2aretiedtogether.Ifthelinkisdirectedend1isthe"rootagent"andend2isthe"leafagent".Thatiswhenend1moves(usingfd,jump,setxy,etc.)end2alsomovesthesamedistanceanddirection.Howeverwhenend2movesitdoesnotaffectend1.

Ifthelinkisundirecteditisareciprocaltierelationship,meaning,ifeitherturtlemovestheotherturtlewillalsomove.Sodependingonwhichturtleismovingeitherturtlecanbeconsideredtherootortheleaf.Therootturtleisalwaystheturtlethatinitiatesthemovement.

Whentherootturtleturnsrightorleft,theleafturtlerotatesaroundtherootturtlethesameamountasifastiffwereattachingtheturtles.Whentie-modeissetto"fixed"theheadingoftheleafturtlechangesbythesameamount.Ifthetie-modeissetto"free"theheadingoftheleafturtleisunchanged.

Thetie-modeofalinkcanbesetto"fixed"usingthetiecommandandsetto"none"(meaningtheturtlesarenolongertied)usinguntietosetthemodeto"free"youneedto:set tie-mode "free".

CodeExample:TieSystemExample

Multiplesourcefiles

The__includeskeywordallowsyoutousemultiplesourcefilesinasingleNetLogomodel.

ThekeywordbeginswithtwounderscorestoindicatethatthefeatureisexperimentalandmaychangeinfutureNetLogoreleases.

Whenyouopenamodelthatusesthe__includeskeyword,orifyouaddittothetopofamodelandhittheCheckbutton,theincludesmenuwillappearinthetoolbar.Fromtheincludesmenuyoucanselectfromthefilesincludedinthismodel.

Whenyouopenincludedfilestheyappearinadditionaltabs.SeetheInterfaceGuideformoredetails.

Youcanhaveanythinginexternalsourcefiles(.nls)thatyouwouldnormallyputintheCodetab:globals,breed,turtles-own,patches-own,breeds-own,proceduredefinitions,etc.Notethoughthatthesedeclarationsallsharethesamenamespace.Thatis,ifyoudeclareaglobalmy-globalintheCodetabyoucannotdeclareaglobal(oranythingelse)withthenamemy-globalinanyfilethatisincludedinthemodel.my-globalwillbeaccessiblefromalltheincludedfiles.Thesamewouldbetrueifmy-globalweredeclaredinoneoftheincludedfiles.

Syntax

Colors

IntheCodetabandelsewhereintheNetLogouserinterface,programcodeiscolor-codedbythefollowingscheme:

KeywordsaregreenConstantsareorangeCommentsaregrayPrimitivecommandsarebluePrimitivereportersarepurpleEverythingelseisblack

Notice

Theremainderofthissectioncontainstechnicalterminologywhichwillbeunfamiliartosomereaders.

Keywords

Theonlykeywordsinthelanguageareglobals,breed,turtles-own,patches-own,to,to-report,andend,plusextensionsandtheexperimental__includeskeyword.(Built-inprimitivenamesmaynotbeshadowedorredefined,sotheyareeffectivelyakindofkeywordaswell.)

Identifiers

Allprimitives,globalandagentvariablenames,andprocedurenamesshareasingleglobalcase-insensitivenamespace;localnames(letvariablesandthenamesofprocedureinputs)maynotshadowglobalnamesoreachother.IdentifiersmaycontainanyUnicodeletterordigitandthefollowingASCIIcharacters:

.?=*!<>:#+/%$_^'&-

SomeprimitivenamesbeginwithtwounderscorestoindicatethattheyareexperimentalandareespeciallylikelytochangeorberemovedinfutureNetLogoreleases.

Scope

NetLogoislexicallyscoped.Localvariables(includinginputstoprocedures)areaccessiblewithintheblockofcommandsinwhichtheyaredeclared,butnotaccessiblebyprocedurescalledbythosecommands.

Comments

Thesemicoloncharacterintroducesacomment,whichlastsuntiltheendoftheline.Thereisnomulti-linecommentsyntax.

Structure

Aprogramconsistsofoptionaldeclarations(globals,breed,turtles-own,patches-own,<BREED>-own,extensions)inanyorder,followedbyzeroormoreproceduredefinitions.Multiplebreedsmaybedeclaredwithseparatebreeddeclarations;theotherdeclarationsmayappearonceonly.

Everyproceduredefinitionbeginswithtoorto-report,theprocedurename,andanoptionalbracketedlistofinputnames.Everyproceduredefinitionendswithend.Inbetweenarezeroormorecommands.

Commandsandreporters

Commandstakezeroormoreinputs;theinputsarereporters,whichmayalsotakezeroormoreinputs.Nopunctuationseparatesorterminatescommands;nopunctuationseparatesinputs.Identifiersmustbeseparatedbywhitespaceorbyparenthesesorsquarebrackets.(Soforexample,a+bisasingleidentifier,buta(b[c]d)econtainsfiveidentifiers.)

Allcommandsareprefix.Alluser-definedreportersareprefix.Mostprimitivereportersareprefix,butsome(arithmeticoperators,booleanoperators,andsomeagentsetoperatorslikewithandin-points)areinfix.

Allcommandsandreporters,bothprimitiveanduser-defined,takeafixednumberofinputsbydefault.(That'swhythelanguagecanbeparsedthoughthereisnopunctuationtoseparateorterminatecommandsand/orinputs.)Someprimitivesarevariadic,thatis,mayoptionallytakeadifferentnumberofinputsthanthedefault;parenthesesareusedtoindicatethis,e.g.(list 1 2 3) (sincethelistprimitiveonlytakestwoinputsbydefault).Parenthesesarealsousedtooverridethedefaultoperatorprecedence,e.g.(1 + 2) * 3 ,asinotherprogramminglanguages.

Sometimesaninputtoaprimitiveisacommandblock(zeroormorecommandsinsidesquarebrackets)orareporterblock(asinglereporterexpressioninsidesquarebrackets).User-definedproceduresmaynottakeacommandorreporterblockasinput.

Operatorprecedencesareasfollows,hightolow:

with,at-points,in-radius,in-cone(allotherprimitivesanduser-definedprocedures)^*,/,mod+,-<,>,<=,>==,!=and,or,xor

ComparedtootherLogos

Thereisnoagreed-uponstandarddefinitionofLogo;itisaloosefamilyoflanguages.WebelievethatNetLogohasenoughincommonwithotherLogostoearntheLogoname.Still,NetLogodiffersinsomerespectsfrommostotherLogos.Themostimportantdifferencesareasfollows.

Surfacedifferences

Theprecedenceofmathematicaloperatorsisdifferent.Infixmathoperators(like+,*,etc.)havelowerprecedencethanreporterswithnames.Forexample,inmanyLogos,ifyouwritesin x + 1,itwillbeinterpretedassin (x + 1).NetLogo,ontheotherhand,interpretsitthewaymostotherprogramminglanguageswould,andthewaythesameexpressionwouldbeinterpretedinstandardmathematicalnotation,namelyas(sin x) + 1.Theandandorreportersarespecialforms,notordinaryfunctions,andthey"shortcircuit",thatis,theyonlyevaluatetheirsecondinputifnecessary.ProcedurescanonlybedefinedintheCodetab,notinteractivelyintheCommandCenter.Reporterprocedures,thatis,proceduresthat"report"(return)avalue,mustbedefinedwithto-reportinsteadofto.Thecommandtoreportavaluefromareporterprocedureisreport,notoutput.

Whendefiningaprocedure,theinputstotheproceduremustbeenclosedinsquarebrackets,e.g.to square [x].Variablenamesarealwaysusedwithoutanypunctuation:alwaysfoo,never:fooor"foo.(Tomakethiswork,insteadofamakecommandtakingaquotedargumentwesupplyasetspecialformwhichdoesnotevaluateitsfirstinput.)Asaresult,proceduresandvariablesoccupyasinglesharednamespace.

Thelastthreedifferencesareillustratedinthefollowingproceduredefinitions:

mostLogos NetLogo

to square :xoutput :x * :xend

to-report square [x]report x * xend

Deeperdifferences

NetLogo'slocalvariablesandinputstoproceduresarelexicallyscoped,notdynamicallyscoped.NetLogohasno"word"datatype(whatLispcalls"symbols").Eventually,wemayaddone,butsinceitisseldomrequested,itmaybethattheneeddoesn'tarisemuchinagent-basedmodeling.Wedohavestrings.InmostsituationswheretraditionalLogowouldusewords,wesimplyusestringsinstead.ForexampleinLogoyoucouldwrite[see spot run](alistofwords),butinNetLogoyoumustwrite"see spot run"(astring)or["see" "spot" "run"](alistofstrings)instead.NetLogo'sruncommandworksonanonymousproceduresandstrings,notlists(sincewehaveno"word"datatype),anddoesnotpermitthedefinitionorredefinitionofprocedures.Controlstructuressuchasifandwhilearespecialforms,notordinaryfunctions.Youcan'tdefineyourownspecialforms,soyoucan'tdefineyourowncontrolstructures.(Youcandosomethingsimilarusinganonymousprocedures,butyoumustusethe->,run,andrunresultprimitivesforthat,youcannotmakethemimplicit.)Anonymousprocedures(akafunctionvaluesorlambda)aretruelexically-scopedclosures.ThisfeatureisavailableinNetLogoandinmodernLisps,butnotinstandardLogo.

Ofcourse,theNetLogolanguagealsocontainsotherfeaturesnotfoundinmostLogos,mostimportantlyagentsandagentsets.

TransitionGuide

ManymodelscreatedinearlierversionsofNetLogoalsoworkinNetLogo5.0.However,somemodelswillneedchanges.Ifanoldmodelisn'tworking,thissectionoftheUserManualmaybeabletohelpyou.

WhatissuesmayarisedependsonwhatversionofNetLogothemodelwascreatedwith.

Thisguideonlycoverschangesmostlikelytocauseissuesforusers.SeetheReleasenotesformorecompletedetailsondifferencesbetweenversions.

ChangesforNetLogo6.0ChangesforNetLogo5.2ChangesforNetLogo5.0ChangesforNetLogo4.1ChangesforNetLogo4.0ChangesforNetLogo3.1

ChangesforNetLogo6.0

TasksreplacedbyAnonymousProcedures

InNetLogo6.0,taskshavebeenreplacedbyanonymousprocedures.Thismeansthattaskisnolongeraprimitive,it'sbeenreplacedbythenewarrowsyntaxforcreatinganonymousprocedures.Similarly,questionmarkvariableslike?,?1,and?2arenowjustordinarynamesinNetLogoandcanbeusedtonameprocedurevariables,letvariables,oranonymousprocedurevariables.Finally,is-reporter-task?andis-command-task?havebeenreplacedbyis-anonymous-reporter?andis-anonymous-command?.

Tomakethistransitioneasier,we'veaddedanautomaticconversionstepwhichshouldallowmostmodelssavedinNetLogo5tobeconvertedtousethenewsyntaxautomatically.Theautoconverterhasbeenasubstantialpieceofeffortandwe'vetesteditonallthemodelsinthemodelslibrary.Touseit,ensurethemodelcompilesandrunproperlyinNetLogo5orlater,thensaveitfromNetLogo5orlater.Then,simplyopenthemodelinNetLogo6.Ifallgoeswell,you'llseetheconverterhaschangedcodeliketask [?1 + ?2] to[ [?1 ?2] -> ?1+ ?2 ].Thequestionmarksaremeanttoserveastemporaryplaceholdersforconversion.Theyenableyourmodeltorun,butyoucan(andshould)replacethesevariableswithmeaningfulnames.Ifyouopenamodelwithtasksandithasnotbeenconverted,theautoconverterwasn'tabletoconvertyourmodel.Ratherthanattempttoautoconvertyourmodelandbreaksomething,themodelwillopen,youwillbeshowntheappropriateerrorsandgivenachancetoedityourmodel.

Whilewehavetestedtheautoconverterthoroughly,weexpecttheretobesomecasesitdoesn'tcover.

Ifyoumakeuseofextensionsthataren'tyetcompiledforNetLogo6,theautoconverterwillnotworkuntilthoseextensionshavebeenupdated.Ifyourcodeusesrunorrunresulttoevaluatestringscontainingtasks,theautoconverterwillnotchangethosestringstobeanonymousprocedures.Tomakerunandrunresultworkasexpected,lookatstringsinyourmodelandchangeanywhichrelyontaskor?-variablestoinsteadrelyonanonymousprocedures

Ifyourmodeldoesn'tfallintotheabovecategoriesanddoesn'tconvertorconvertsincorrectly,pleaseemailourfeedbackaddressandwe'llbehappytoofferwhateverassistancewecan.

https://github.com/NetLogo/NetLogo/wiki/Release-notes


Linkreportersoverhauledtobemoreconsistentandflexible

InpreviousversionsofNetLogo,linkreportershavehadanumberofinconsistenciesregardingdirectedandundirectedlinks.Forexample,my-linkswouldreportalllinksconnectedtoaturtle,whereaslink-neighborswouldonlyreportneighborsconnectedbyundirectedlinks.Furthermore,itwasquitedifficulttoworkwithmodelswherethelinkscouldeitherbedirectedorundirected.

Toalleviatetheseissues,thelinkprimitiveshavebeenoverhauledin6.0.Thesechangesonlyaffectexistingmodelsthatusebothdirectedandundirectedlinkswhilealsousingtheunbreededlinkprimitives.

Thechangesareasfollows:

Linkreportersthatcontaintheword"out"nowutilizebothdirected,outgoinglinksandundirectedlinks.Thatis,theynowspecifylinksthatcanbeusedtogetfromthecurrentnodetoothernodes.Forexample,out-link-neighbor?willreporttrueifthecurrentturtleisconnectedtothegiventurtlebyeitheranoutgoingdirectedlinkoranundirectedlink.Ifyouonlywantdirected,outgoinglinks,youcanuseabreed-specificreporterormy-out-links with [ is-directed? self ].Generally,whenworkingwithmodelsthathavebothdirectedandundirectedlinks,youwillprobablywanttousethe"out"primitivesformostthingsnow.Linkreportersthatcontaintheword"in"nowutilizebothdirected,incominglinksandundirectedlinks.Thatis,theynowspecifylinksthatcanbeusedtogettothecurrentnodefromothernodes.Forexample,in-link-neighbor?willreporttrueifthecurrentturtleisconnectedtothegiventurtlebyeitheranincomingdirectedlinkoranundirectedlink.Ifyouonlywantdirected,incominglinks,youcanuseabreed-specificreporterormy-in-links with [ is-directed? self ].Linkreportersthatdonotspecify"out"or"in"utilizealllinks.

Furthermore,therearenolongerrestrictionsregardingwhichreporterscanbeusedwithwhichbreeds.Forunbreededlinks,thismakesitpossibletousethesameprimitivesregardlessofwhetheryournetworkendsupbeingdirectedorundirected.

Thenewbehavior(includingallchangedprimitives)issummarizedbythefollowingtable,where"un"referstoundirectedlinks,"out"referstodirected,outgoinglinks,and"in"referstodirected,incominglinks.

Newlinkreporterbehavior

Oldlinkreporterbehavior

RemovalofApplets

Oracle,thecompanybehindJava,hasannouncedthatJavaappletsaredeprecated(seethisblogpostformoreinformation).Thiscomesasthemajorbrowsershaveremovedsupportforplug-ins(likejavaapplets)orannouncedthattheyplantodoso.

https://blogs.oracle.com/java-platform-group/entry/moving_to_a_plugin_free

Insteadofusingappletstodistributeyourmodel,NetLogoofferstheoptiontoexporttoNetLogoWeb.WhileNetLogoWebdoesn'tyetofferthefullfunctionalityofdesktopNetLogo(inparticular,extensionsaren'tsupported),itisnowcapableofrunningmostofthemodelsintheNetLogomodelslibraryandwehopethatmostmodeldistributorswillfindthatitmeetstheirneeds.ToexporttoNetLogoWeb,choosethe"SaveAsNetLogoWeb"optionfromthe"File"menu.

ChangestotheNetLogoUserInterface

UserswillnoticeseveraltweakstotheNetLogoUserinterfacewhenopeningNetLogo6forthefirsttime.We'veremovedthebarborderabovetheview.Toopenthe3DViewin6.0,youcanrightclickontheviewandchoose"Switchto3DView",orchoosethesameoptionfromthe"Tools"menu.Ticksarenowdisplayedintheinterfacetabtoolbarbeneaththespeedslider.Toadjustthelabelusedfor"ticks"andotherviewproperties,youcanchoosethe"Settings"buttonatthefarrightoftheinterfacetabtoolbarorright-clickontheviewandchoose"Edit..."fromthecontextmenuthatappears.

NobodyNotPermittedasaChooserValue

InNetLogo6.0,nobodyisnolongeravalidchooservalue.Justasyoucan'tputturtle 0orturtles,nobodyreferstoanon-literalvaluewhichisn'tsupportedinchoosers.Aspartofthistransition,chooserscontainingnobody(ornobodywithinanestedlist)willhaveallusesofnobodychangedto"nobody"whenopenedinNetLogo6.0.

Breedsmusthavesingularandpluralnames

InNetLogo6.0,youmustspecifybothpluralandsingularbreednames.Inpriorversions,declarationslikebreed [mice]werelegal,butthissupporthasbeenremovedin6.0.Ifyouhavemodelswhichuseonlypluralbreednames,itisrecommendedthatyouconvertthemtospecifybothnamesbeforeopeningin6.0sincedoingsowillpermittheNetLogoconvertertoworkmosteffectivelyonanyothercodeinyourmodelwhichneedsconversion.

Removalof"Movie"Prims

TheNetLogomovieprimshadn'tbeenupdatedinquitesometimeandgeneratedinvalidquicktimemoviefiles.Theyhavebeenreplacedbyprimsinthenewvidextension.ThefulldocumentationforthevidextensionisavailableintheVidExtensionsectionofthemanual.Aswithallextensions,userswillneedtoincludevidintheextensionssectionoftheirNetLogomodel.

Manyofthemovieprimitiveshavedirectparallelsinthevidextensionwhichcanbefoundinthefollowingtable:

movieprim vidprimmovie-cancel vid:reset-recorder

movie-close vid:save-recording file-name

movie-grab-view vid:record-view

movie-grab-interface vid:record-interface

movie-start file-name vid:start-recorder optional-width optional-height

movie-status vid:recorder-status

WhenyoufirstopenafileinNetLogo6.0,yourfilewillbeautomaticallyconvertedtousethe

newprimitives.Thiswillincludeaddinganewglobalvariable-_recording-save-file-nametotrackthenameoftheactiverecording,aswellasaddingthevidextensiontothemodel.Youshouldverifythattheconversiontookplacecorrectly.Thereisnoreplacementformovie-set-frame-rate.Thevidextensionrecordsframesat25persecond,slightlymorethanthedefault15frames-per-secondofthemovieprims.Ifyourrecordingissensitivetoframerate,considerrecordingeachexistingframetwice(2/25isfairlycloseto1/15)orconsiderusingapostprocessingtool(likegstreamerorffmpeg)toadjustthevideoplaybackspeed.

ImprovedNameCollisionDetection

InNetLogo6.0,expandederror-checkingintheNetLogocompilercausesmodelswhichdefineundirected-link-breed [ undirected-links undirected-link ] and/ordirected-link-breed [ directed-links directed-link ]toerrorforredefiningaprimitivereporter(eitheris-directed-link?oris-undirected-link?).Ifyourmodeldoesn'tuseis-directed-link?oris-undirected-link?atall,simplychangingthebreednamesshouldresolvetheerror.

Ifyouusedeitheroftheis-<directedness>-link?prim,thereareseveralwaysyoumightmodifyyourmodeltoaccountforthischange.Ifyourmodelhasnootherbreededlinks,considerremovingthelinkbreedandusingthebuilt-inlinkprimitives.Ifyourmodelhasotherbreededlinks,butonlyofdifferentdirectedness,simplychangingthebreedname(andallrelatedprimitivenames)shouldresolvetheproblem.Notethatinthiscaseis-directed-link?and/oris-undirected-link?continuetobehavethesameasbefore.Ifyourmodelhasotherbreededlinksofthesamedirectedness,thechangewillvarydependingonyourmodel.Thebreedname(s)mustbechanged,butyoumustdecidewhetheryouusedis-directed-link?/is-undirected-link?tochecklinkdirectedneessortocheckthatlinkbreedmembership.Ifyouusedittochecklinkdirectednessleavingitas-isshouldkeepthecurrentbehaviorofthemodel.Otherwise,itcansimplybereplacedbyis-<breed>?.

Removalofhubnet-set-client-interface

Thehubnet-set-client-interfaceprimitivewasrenderedobsoletebytheintroductionoftheHubNetclienteditorandendofsupportforcalculatorHubNet.Wehavefounditusedinveryfewmodelsandhavedecidedtoremoveitfromthelanguage.Onopeninganexistingmodelin6.0,theautoconvertershouldremoveallusesofhubnet-set-client-interfacefromyourcode.

Improved&UpdatedExtensionsAPI

OneofourgoalsinNetLogo6.0hasbeentomakeiteasiertodevelopextensionsandeasytodevelopmorepowerfulextensions.Tothatend,we'vebumpedtheextensionAPIfrom5.0to6.0.Existingextensionswillneedtorecompilechangingthe"NetLogo-Extension-API-Version"intheirjar'sMANIFEST.MFfrom5.0to6.0.

Someofthechangeswe'vemadetotheextensionsAPIinclude:

org.nlogo.api.Contextnowallowsaccesstothecurrentworldandworkspaceobjectswithoutrequiringacasttoanorg.nlogo.nvm.ExtensionContext.org.nlogo.api.WorkspacehasbeenintroducedasastableAPIforextensionstodependon.ANetLogojarisnowavailablefromBinTray.

Forafulllistofchangesbetween5.0and6.0,pleasevisitourExtensionTransitionGuideonGitHub.

https://github.com/NetLogo/NetLogo/wiki/Hexy-Extension-Transition-Guide

Inserviceofmakingiteasiertobuildextensions,we'veexpandedandimprovedtheNetLogoExtensionPluginforsbt,theScalaBuildTool.SbtisapowerfultoolforbuildingJVMprojectsandcanbeusedinprojectsthatuseScala,Java,oracombinationofthetwo.We'renowusingtheExtensionPlugintobuildallofthebundledextensionsandwestronglyrecommendextensionauthorstakeadvantageofthepluginasitmakesconfiguringaNetLogoextensionbuildextremelystraightforward.ThepluginhandlesfetchingtheNetLogojarwhichextensionscompileagainstaswellasgenerationofajarfortheextensioncontainingtheappropriatemetadata.

Addrangeprimitive

AnewrangeprimitivewasaddedinNetLogo6.As"range"mayappearinexistingmodelsasaprocedureorvariablename,wehaveaddedanautoconversionstepwhichwillensurethatthesemodelscontinuetooperateimmediatelyuponopeninginNetLogo6.ExistingusesofrangeinmodelsauthoredbeforeNetLogo6willbeconvertedto_rangeuponfirstopeninginNetLogo6.Oncethemodelopens,youcanrename_rangetosuityourmodel.


hsbprimitives

In5.2,thehsbprimitiveshavebeenchangedtoworkwiththestandardscalevaluesof360forhue,and100forsaturationandbrightness.Thisaffectstheprimitiveshsb,extract-hsbandapproximate-hsb.

Theoldprimitives,scaledto255,areautomaticallytransitionedtoandhavebeenrenamed__hsb-old,__extract-hsb-oldand__approximate-hsb-old.

GoGoextension

TheGoGoextensionhasbeenupgradedtousenewerGoGoboardswiththeHIDinterface.Manyoftheolderprimitivesnolongerwork,andwillalertyoutoupgradingyourGoGoboard'sfirmware.

Ifyouneedtocontinuetouseaserialinterface,youcanusethebundledgogo-serialextension.Changeyourmodeltousegogo-serialasopposedtogogo.Moredetails[here](https://github.com/NetLogo/NetLogo/wiki/GoGo-Upgrade).

IfyoucannotupgradetousethenewHIDextensionnorthenewserialextension,theoriginalextensioncanbefoundathttps://github.com/NetLogo/GoGo-RXTX-Extension


Plotting

In5.0,youdon'thavetoputyourplottingcodeintheCodetabanymore.Instead,youcanputitinsidetheplotsthemselves,intheInterfacetab.

Nonetheless,theoldstyleandalloftheexistingplottingprimitivesarestillsupported.Werecommendchangingyourmodeltousethenewstyle,butifyoudon't,itshouldstillwork.

https://github.com/NetLogo/NetLogo-Extension-Plugin

http://www.scala-sbt.org/

Thefollowingexampleshowshowtochangeamodeltousethenewstyle.SupposeyouhaveatypicalNetLogo4.1modelwithoneplotcalled"populations"andtwopenscalled"robots"and"humans".Theoldcodemightlooklike:

to setup clear-all ... do-plottingend

to go ... tick do-plottingend

to do-plotting set-current-plot "populations" set-current-plot-pen "robots" plot count robots set-current-plot-pen "humans" plot count humansend

Herearethestepstomakethetransition:

Copytheplot count robotscommandandpasteitintotheUpdateCommandsfieldfortherobotspenintheploteditdialog.Removeitfromthedo-plottingprocedure.Theplot count humanscommandcanbemovedinthesamewayforthehumanspen.Afterthoselinesareremovedfromthedo-plottingprocedure,itdoesn'tactuallydoanythinganymore!Removeit.Thefinalstepistoreplacethedo-plottingprocedurecallsinsetupandgo.Insetup,thedo-plottingcallshouldbechangedtoreset-ticks.Ingo,thedo-plottingcallshouldbechangedtotick.reset-ticksandtickwillbothcauseplottingtohappenautomatically.

Theresulting(muchsimpler)codelookslikethis:

to setup clear-all ... reset-ticksend

to go ... tickend

FormoredetailsonhowplottingworksinNetLogo5.0,seethePlottingSectionsoftheProgrammingGuideandtheInterfaceGuide.Fordetailsonhowplottinginteractswiththetickcounter,readon.

Tickcounter

Thewaythetickcounterworkshaschangedin5.0.Insteadofbeinginitiallysetto0,thetickcounterisinitiallyblank.

reset-ticks

Youmustusereset-tickstostartthetickcounterat0beforeusingticks,tickortick-

advanceforthefirsttime.

reset-ticksshouldgoattheendofyoursetupprocedure.Puttingittherewillallowyourmodeltoworkwith5.0'snewplottingfeatures.

reset-ticksandplotting

In5.0,youdon'thavetoputyourplottingcodeintheCodetabanymore.Instead,youcanputitinsidetheplotsthemselves,intheInterfacetab.Codeinsideplotsistriggeredbyreset-ticksandtick.Resettingthetickcounterrunsplotsetupcode,andthenitalsorunsplotupdatecodetoplottheinitialstateofthemodel.Theinitialstateofthemodelwon'tbeinplaceuntiltheendofsetup,sothat'swhyreset-ticksshouldgoattheend.

__clear-all-and-reset-ticks

InorderformodelsfrompreviousNetLogoversionstoworkin5.0withoutchanges,whenanoldmodelisopenedin5.0,anyoccurrencesofclear-all(orca)areautomaticallychangedto__clear-all-and-reset-ticks,whichcombinestheeffectsofclear-allandreset-ticks.Thetwounderscoresonthenameindicatethatthisisnotanormalprimitive,butexistsonlyforbackwardscompatibility.

Youshouldremove__clear-all-and-reset-ticksfromyourcode,replaceitwithclear-all,andputreset-ticksattheendofyoursetupprocedure.(Thisdoesn'thappenautomaticallybecausethestructureofNetLogomodelsistoofree-formforanautomaticconvertertoreliablymakethechangeforyou.)

Unicodecharacters

NetLogo5.0fullysupportsinternationalcharacterscross-platform,usingtheUnicodecharacterset.NetLogo5.0modelfilesalwaysrepresentUnicodecharactersusingtheUTF-8encoding.

PreviousversionsofNetLogoallowedUnicodecharacterstobeusedinsomecontexts.However,modelfilesweresavedintheplatform'sdefaultencoding,whichonmostsystemswassomethingotherthanUTF-8.Characterswerehandledcorrectlyonthesameplatform(e.g.twoWindowsmachines),butcouldbealteredifthemodelwasmovedbetweenplatforms(e.g.fromWindowstoMacorviceversa).

WhenopeninganexistingmodelinNetLogo5.0,ifthemodelcontainsinternationalorothernon-ASCIIcharacters,thecharactersmaybeinterpretedincorrectly,becausetheywereoriginallywritteninaplatform-specificencoding,butthenreadbackininUTF-8.

Ifonlyafewcharactersareaffected,youmightfinditeasiestjusttofixthemmanually.

Butifyouexpectalargenumberofcharacterstobeaffected,andyouwantthemtranslatedautomatically,youcanuseathirdpartyutilitytore-encodeyour.nlogofilefromitsoriginalencodingintoUTF-8.Afterconversion,openthemodelinNetLogo5.0andallcharactersshouldbecorrect.

Infotabs

NetLogo5.0usestheMarkdownmarkuplanguagetoallowyoutoformatyourInfotab,includingheaders,boldanditalics,images,andsoforth.

EarlierversionsofNetLogousedacustommarkuplanguagewithmuchmorelimitedcapabilities.

Whenopeningamodelfromanolderversion,NetLogo5.0translatesyouroldmarkupintoMarkdown.Mostofthetimethisproducesgoodresults,butyoumaywanttochecktheresultsyourselfandmakesurethatyourInfotabstilllooksgood.

Modelspeed

InNetLogo5.0everymodelhasa"targetframerate"whichaffectsthedefaultspeedatwhichthemodelruns,whenthespeedsliderisinthemiddle,onthe"normalspeed"setting.

Thedefaulttargetframeratefornewmodels,andformodelsthatwerecreatedinearlierversionsofNetLogo,is30framespersecond.Ifyouareusingtick-basedupdates,aswerecommendformostmodels,thenthattranslatesto30tickspersecond.

Ifyourmodelrunsslowerin5.0thanitranin4.1,it'sprobablyjustbecauseitsspeedisbeinglimitedbythisrate.Ifyouwant,youcanpresstheSettingsbuttonintheInterfacetabandchangetheframeratetoahighernumber.

Someoldmodelsusedtheeverycommandtosetadefaultspeed.Inmostcasethiscanbenowremovedfromthecode,andthetargetframeratesettingusedinstead.

Listperformance

TheunderlyingdatastructureforNetLogolistshaschanged.

InNetLogo4.1,aNetLogolistwasrepresentedinternallyasasinglylinkedlist.Someoperationsonsinglylinkedlistsarefast(suchasfirstandbutfirst)butothersareslowbecausetheycouldrequiretraversingthewholelist(suchasitemandlast).

InNetLogo5.0,listsarenowactuallytreesinternally.Asaresult,someoperationsarealittleslower,butotheroperationsaredrasticallyfasteronlonglists.SeetheListssectionoftheProgrammingGuidefordetails.

Somemodelsmayrunalittleslowerwiththenewdatastructure,especiallyifyoumakeheavyuseofshortlists.Butothermodelswillrunfaster--perhapsdramaticallyfaster.

Somespecialwaysofwritinglist-processingcodethatwereusefulinNetLogo4.1arenolongerneededin5.0.Forexample,sincein4.1fputwasfastandlputwasslow,modelerssometimesbuiltuplistsinreverseorderusingfput,perhapscallingreverselatertorestoretheintendedorder.InNetLogo5.0,youdon'tneedtocodethatwayanymore.fputandlputarethesamespeed.

ExtensionsAPI

Ifyouaretheauthorofanextension,youwillneedtorecompileitagainstthe5.0NetLogo.jarandlibdirectoryforittoworkwith5.0.

Youmayalsoneedtobeawareofthefollowingchanges:

Syntaxconstants

Thecodeforspecifyingthesyntaxofaprimitivehaschangedslightly,forexample

Syntax.TYPE_STRINGisnowSyntax.StringType().(FromJava,thepairofparenthesesattheendisrequired.InScala,youcanomitthem.)

LogoListconstruction

Onesignificantchangeisthatorg.nlogo.api.LogoListnolongerhasapublicconstructor.Instead,therearetwonewwaystoconstructaLogoList.

Ifyouhaveajava.lang.Iterable,youcancopythecontentsintoafreshLogoListbypassingittothestaticmethodLogoList.fromJava().Seethearrayextensionsourcecodeforasampleusage.

Or,tobuildupanewlistoneitematime,useorg.nlogo.api.LogoListBuilder.TheExtensionsGuidehassamplecodeshowingtheuseofLogoListBuilder.

Primitiveclasses

InpriorNetLogoversions,theextensionsAPIrequiredthateachextensionprimitivehaveitsownseparatetop-levelclasswithano-argumentconstructor.Theselimitationshavenowbeenlifted.Also,api.Primitiveobjectsarenowmadeonlyonce,whentheextensionisloaded,insteadofeverytimetheCodetabwasrecompiled.


Combiningsetandof

Thefollowingsyntaxisnolongersupported:

set [<variable>] of <agent> <value>

Commandsofthisformmustberewrittenusingask:

ask <agent> [ set <variable> <value> ]

Or,ifthenewvaluemustbecomputedbytheaskingagentandnotbytheagentwhosevariableisbeingset:

;; OPTION #1 (using let):let new-value <value>ask <agent> [ set <variable> new-value ]

;; OPTION #2 (using myself):ask <agent> [ set <variable> [value] of myself ]

Soforexample,this:

set [color] of turtle 0 red

Canberewrittenas:

ask turtle 0 [ set color red ]

Itisnotnecessarytouseletormyselfsinceredisredfromthepointofviewofbothagents.

However,this:

set [color] of turtle 0 color

Mustberewrittenas:

let new-color colorask turtle 0 [ set color new-color ]

or

ask turtle 0 [ set color [color] of myself ]

inordernottochangethemeaning,sincethetwoagentsmayhavedifferentstartingvaluesforcolor.Theformusingmyselfisbriefer,buttheformerusingletmaybeconsideredclearer,dependingoncontextandindividualpreference.


Whonumbering

PriortoNetLogo4.0,adeadturtle'swhonumber(storedinthewhoturtlevariable)couldbereassignedtoalaternewbornturtle.InNetLogo4.0,whonumbersareneverreuseduntilwhonumberingisresetto0bytheclear-allorclear-turtlescommand.Thischangeinbehaviormaybreakafewoldmodels.

Turtlecreation:randomizedvs."ordered"

NetLogo4.0providestwodifferentobservercommandsforcreatingturtles,create-turtles(crt)andcreate-ordered-turtles(cro).

crtgivesthenewturtlesrandomcolorsandrandomintegerheadings.croassignscolorssequentiallyandgivestheturtlessequentialequallyspacedheadings,withthefirstturtlefacingnorth(headingof0).

PriortoNetLogo4.0,thecrtcommandbehavedthewaycrodoesnow.Ifyouroldmodeldependsonthe"ordered"behavior,youwillneedtochangeyourcodetousecroinsteadofcrt.

Itiscommonforoldmodelsthatusedcrttocontainextracommandstorandomizethenewturtles'headings,forexamplert random 360orset heading random 360.Thesecommandsarenolongernecessarywhenusedinsidecrt.

Addingstringsandlists

PriortoNetLogo4.0,the+(addition)operatorcouldbeusedtoconcatenatestringsandjoin

lists.IncurrentNetLogo,+onlyworksonnumbers.Toconcatenatestrings,usethewordprimitive;tojoinliststogether,usethesentenceprimitive.Thislanguagechangewasmadetoincreasethespeedofcodethatuses+.

Oldcode:

print "There are " + count turtles + " turtles."

Newcode:

print (word "There are " count turtles " turtles.")

Likewise,ifyouneedtoconcatenatelists,useSENTENCE.

Thischangeisnothandledautomaticallywhenconvertingoldmodels;userswillneedtochangetheircodebyhand.

Weknowthischangewillbeawkwardforuserswhoareusedtotheoldsyntax.Wehavemadethischangeforefficiencyandconsistency.Wecanimplementanadditionoperatorthatonlyaddsnumbersmuchmoreefficientlythanonethathandlesseveraldifferentdatatypes.Becauseadditionissuchacommonoperation,NetLogo'soverallspeedisaffected.

The-atprimitives

Theobservermaynolongerusepatch-at,turtles-at,andBREEDS-at.Usepatch,turtles-onpatch,andBREEDS-on patchinstead.Notethatpatchnowroundsitsinputs(beforeitonlyacceptedintegerinputs).

Links

NetLogo3.1hadsupportsforusinglinkstoconnectturtlestomakenetworks,graphs,andgeometricfigures.Thelinkswerethemselvesturtles.

InNetLogo4.0,insteadoflinksbeingturtles,linksarenowanindependentfourthagenttype,rightalongsideobserver,turtles,patches.Theprimitivesinvolvinglinksarenolongerconsideredexperimental;theyarenowfullypartofthelanguage.

Modelsthatusetheold,experimentalturtle-basedlinkprimitiveswillneedtobeupdatedtouselinkagents.Thedifferencesarenothuge,buthandupdatingisrequired.

LinksaredocumentedintheLinkssectionoftheProgrammingGuide,andintheNetLogoDictionaryentriesforthelinkprimitives.SeetheNetworkssectionoftheModelsLibraryforexamplemodelsthatuselinks.Therearealsosomelink-basedCodeExamples.

Firstyouwillneedtoremoveanybreedscalled"links"ifyouareonlyusingonetypeoflinksthenyouwillnothavetousebreedsatall.Ifyouareusingmultipletypesoflinksseeundirected-link-breedanddirected-link-breed.Commandsandreportersthatcontaintheword"links"(like__create-links-with,etc.)willautomaticallybeconvertedtothenewformwithoutunderscores(create-links-with).However,primitivesthatuseadifferentbreedname(suchas"edges")willnotbeconverted.Youwillneedtoremovetheunderscoresbyhandandunlessyouaredeclaringalinkbreedwiththatnameyouwillneedtochangethebreeddesignationto"links".

Thecommandsremove-link(s)-with/from/tonolongerexist.Insteadyoushouldaskthelinksinquestiontodie.

Forexample:

ask turtle 0 [ __remove-links-with link-neighbors ]

becomes

ask turtle 0 [ ask my-links [ die ] ]

Severalofthelayoutcommandshaveslightlydifferentinputs,thefirsttwoinputsaregenerallyaturtleagentsetandalinkagentsettoperformthelayouton.Seethedictionaryentriesfordetails.layout-spring,layout-radiallayout-tutte

Youmayalsoneedtorearrangethedeclarationofturtles-ownvariables,sincelinkswereonceactuallyturtles.Anyvariablesthatapplytolinksshouldbemovedintoalinks-ownblock.

Sincelinksarenolongerturtlestheynolongerhavethebuilt-inturtlevariables(thoughsomeofthelinkvariablesarethesamesuchascolorandlabel.Ifyouformerlyusedthelocationoflinkturtlesyouwillnowneedtocalculatethemidpointofthelink.Thisisfairlysimpleinanon-wrappingworld.

to-report link-xcor report mean [xcor] of both-endsend

to-report link-ycor report mean [ycor] of both-endsend

itisalittlebittrickierinawrappingworldbutstillfairlystraightforward.

to-report link-xcor let other-guy end2 let x 0 ask end1 [ hatch 1 [ face other-guy fd [distance other-guy] of myself / 2 set x xcor die ] ] report xend

andsimilarlyforycor.

Ifyouusedeitherthesizeorheadingofthelinkturtlesyoucanusethereporterslink-lengthandlink-headinginstead.

New"of"syntax

Wehavereplacedthreedifferentlanguageconstructs,-of(withhyphen),value-from,andvalues-fromwithasingleofconstruct(nohyphen).

old newcolor-of turtle 0 [color] of turtle 0

value-from turtle 0 [size * size] [size * size] of turtle 0

mean values-from turtles [size] mean [size] of turtles

Whenofisusedwithasingleagent,itreportsasinglevalue.Whenusedwithanagentset,itreportsalistofvalues(inrandomorder,sinceagentsetsarealwaysinrandomorder).

Notethatwhenopeningoldmodelsinthenewversion,-of,value-from,andvalues-fromwillautomaticallybeconvertedtouse"of"instead,butsomenestedusesoftheseconstructsaretoocomplexfortheconverterandmustbeconvertedbyhand.

Serialask

Theaskcommandisnowserialratherthanconcurrent.Inotherwords,theaskedagentswillrunoneatatime.Notuntiloneagentcompletelyfinishestheentirebodyoftheaskdoesthenextagentstart.

Notethateventheoldaskwasnevertrulyconcurrent;wesimulatedconcurrentexecutionbyinterleavingexecutionamongtheagentsusingaturn-takingmechanismdescribedintheNetLogoFAQ.

Wehavemadethischangebecauseinourexperience,usersoftenwrotemodelsthatbehavedinunexpectedwaysduetothesimulatedconcurrency,butrarelywrotemodelsthatbenefitedfromthesimulatedconcurrency.Modelsexhibitingunexpectedbehaviorcouldusuallybefixedbyaddingthewithout-interruptioncommandintherightplaces,butitwasdifficultforuserstoknowwhetherthatcommandwasneededandifso,where.

InNetLogo4.0,without-interruptionisnolongernecessaryunlessyourmodelusesask-concurrent(oraturtleorpatchforeverbuttoncontainingcodethatdependsonsimulatedconcurrency).Inmostmodels,allusesofwithout-interruptioncanberemoved.

Thesimulatedconcurrencyformerlyemployedby"ask"isstillaccessibleinthreeways:

Youmayusetheask-concurrentprimitiveinsteadofasktogettheoldsimulatedconcurrency.(Wedon'trecommendthis,though.)CommandsissuedintheCommandCenterdirectlytoturtles,patches,orlinkshaveanimpliedask-concurrent.Turtle,patch,andlinkforeverbuttonshaveanimpliedask-concurrentaswell.

Notethataskitselfisalwaysserialregardlessofthecontextinwhichitisused,however.

InourownModelsLibrary,modelsthatmakeuseofthisconcurrencyarerare.Aprominentexample,though,isTermites,whichusesaconcurrentturtleforeverbutton.

Tickcounter

NetLogonowhasabuilt-intickcounterforrepresentingthepassageofsimulatedtime.

Youadvancethecounterbyoneusingthetickcommand.Ifyouneedtoreaditsvalue,there'sareportercalledticks.Theclear-allcommandresetsthetickcounter;sodoesreset-ticks.

Inmostmodelsthetickcounterwillbeinteger-valued,butifyouwanttousesmallerincrementsoftime,youcanusethetick-advancecommandtoadvancethetickcounterby

anypositiveamount,includingfractionalamounts.SomeModelsLibrarymodelsthatusetick-advanceareVectorFieldsandtheGasLabmodels.

ThevalueofthetickcounterisdisplayedinthetoolbaratthetopoftheInterfacetab.(YoucanusetheSettings...buttoninthetoolbartohidethetickcounter,orchangetheword"ticks"tosomethingelse.)

Viewupdatemodes

Inthepast,NetLogoalwaystriedtoupdatetheviewabout20timesasecond.We'renowcallingthat"continuous"viewupdates.Thebiggestproblemwithitwasthatyouusuallywantupdatestohappenbetweenmodelticks,notinthemiddleofatick,sowehadacheckboxonbuttonsthat(bydefault)forcedadisplayupdateaftereverybuttoniteration.Thatmadesureupdateshappenedbetweenticks,butitdidn'tgetridoftheintermediateupdates.Youhadtouseno-displayanddisplaytolockthemout.

Westillsupportcontinuousupdates.TheyarethedefaultwhenyoustartupNetLogo.ButmostModelsLibrarymodelsnowusetick-basedupdates.Withtick-basedupdates,updateshappenonlywhenthetickcounteradvances.(Thedisplaycommandcanbeusedtoforceadditionalupdates;seebelow.)

Theadvantagesoftick-basedupdatesasweseethemareasfollows:

1. Consistent,predictableviewupdatebehaviorwhichdoesnotvaryfromcomputertocomputerorfromruntorun.

2. Intermediateupdatescanconfusetheuserofyourmodelbylettingthemseethingstheyaren'tsupposedtosee,whichmaybemisleading.

3. Increasedspeed.Updatingtheviewtakestime,soifoneupdatepertickisenough,thenenforcingthanthereisonlyoneupdatepertickwillmakeyourmodelfaster.

4. Insteadofhavinga"forceviewupdate"checkboxineverybuttonlikeinNetLogo3.1,weonlyneedonechoicewhichappliestotheentiremodel.

5. Usingthespeedslidertoslowdownamodelnowjustinsertspausesbetweenticks.Sowithtick-basedupdates,setupbuttonsarenolongeraffectedbythespeedslider.Thiswasarealannoyancewiththeoldspeedslider.(Theannoyancepersistsformodelsthatusecontinuousupdates,though.)

Asmentionedabove,mostmodelsinourModelsLibrarynowusetick-basedupdates.

Evenformodelsthatwouldnormallybesettotick-basedupdates,itmaybeusefultoswitchtocontinuousupdatestemporarilyfordebuggingpurposes.Seeingwhat'sgoingonwithinatick,insteadofonlyseeingtheendresultofatick,couldhelpwithtroubleshooting.

Ifyouswitchyourmodeltousetick-basedupdates,you'llalsoneedtoaddthetickcommandtoyourcode,otherwisetheviewwon'tupdate.(Notethattheviewstillalwaysupdateswhenabuttonpopsuporacommandenteredinthecommandcenterfinishes,though.Soit'snotliketheviewwilljuststayfrozenindefinitely.)

Howtomakeamodeluseticksandtick-basedupdates

Herearethestepstofollowtoconvertyourmodeltouseticksandtick-basedupdatesinNetLogo4.0:

1. IntheInterfacetabtoolbar,ontherighthandsidewhereitsays"updateview:",changethesettingfrom"continuously"to"onticks".

2. Addthetickcommandtoyourgoprocedure,atorneartheend.InModelsLibrary

modelswealwaysputtickaftertheagentsmovebutbeforeanyplottingcommands.That'sbecausetheplottingcommandsmightcontainsomethinglikeplotxy ticks ...andwewantthenewvalueofthetickcounterused,nottheoldone.Mostmodelsdon'trefertothetickcounterintheirplottingcommands,butnonetheless,forconsistencyandtoavoidmistakeswesuggestalwaysputtingtickbeforetheplottingcommands.

Somemodelswillrequiresomeadditionalchanges:

1. Ifyourmodelalreadyhasaglobal"ticks"or"clock"or"time"variable,getridofit.Usethetickcommandandticksreporterinstead.(Ifyourmodelusesfractionalincrementsoftime,usetick-advanceinsteadoftick.)Ifyouhadamonitorforthatvariable,youcangetridofit;there'snowatickcounterinthetoolbar.

2. clear-allresetsthetickcountertozero.Ifyoudon'tuseclear-allinyoursetupprocedure,thenyoumayneedtoaddreset-tickstoresetthecountertozero.

3. Ifyouusedno-displayanddisplaytopreventviewupdatesfromhappeninginthemiddleofgo,youcangetridofthem.

4. Ifyourmodelneedstoupdatetheviewwithoutadvancingthetickcounter(examples:Party,DiceStalagmite,networkmodelswithanimatedlayout,modelswithmouseinteractionbuttons),usethedisplaycommandtoforceadditionalviewupdatessotheusercanseewhatisgoingon.

Speedslider

PreviousversionsofNetLogohadaspeedsliderthatcouldbeusedtomakemodelsrunslower,soyoucanseewhat'sgoingon.

InNetLogo4.0,theslidercanbeusedtospeedupmodelsaswell.Itdoesthisbyupdatingtheviewlessfrequently.Updatingtheviewtakestime,sothefewerupdates,thefasterthemodelruns.

Thedefaultpositionofthesliderisinthecenter.Whenyou'reatthecenter,theslidersays"normalspeed".

Asyoumovethesliderawayfromthecenterposition,themodelwillgraduallyrunfasterorslower.

Atveryhighspeeds,viewupdatesbecomeveryinfrequentandmaybeseparatedbyseveralseconds.Itmayfeellikethemodelisactuallyrunningslower,sincetheupdatesaresoinfrequent.Butwatchthetickcounter,orotherindicatorssuchasplots,andyou'llseethatyes,themodelreallyisrunningfaster.Iftheinfrequentupdatesaredisconcerting,don'tpushtheslidersofarover.

Whenusingtick-basedupdates,slowingthemodeldowndoesnotcauseadditionalviewupdates.Rather,NetLogosimplypausesaftereachtick.

Whenusingcontinuousupdates,slowingthemodeldownmeansviewupdatesbecomemorecloselyspaced.Ifyoupushthespeedslidermorethanhalfwaytotheleft,themodelwillberunningsoslowlythatyoucanwatchturtlesmovingoneatatime!ThisisnewinNetLogo4.0;inpreviousNetLogoversions,nomatterhowslowlyyouranamodel,youwouldneverseetheagentsinanaskmovingoneatatime;alltheagentsinanaskalwaysappearedtomovetogether.

Numbers

NetLogonolongermaintainsaninternaldistinctionbetweenintegersandfloatingpoint

numbers.Soforexample:

Old:

observer> print 33observer> print 3.03.0observer> print 1 + 23observer> print 1.5 + 1.53.0observer> print 3 = 3.0true

(Thelastlineshowsthatalthoughthedistinctionbetweeninteger3andfloatingpoint3.0wasmaintained,thetwonumberswerestillconsideredequal.)

New:

observer> print 33observer> print 3.03observer> print 1 + 23observer> print 1.5 + 1.53observer> print 3 = 3.0true

Weexpectthatonlyraremodelswillbenegativelyimpactedbythischange.

AbenefitofthischangeisthatNetLogonowsupportsamuchlargerrangeofintegers.Theoldrangewas-2,147,483,648to2,147,483,647(around+/-2billion);thenewrangeis+/-9,007,199,254,740,992(around+/-9quadrillion).

Agentsetbuilding

NetLogo3.1(andsomeearlierversions)includedprimitivescalledturtles-fromandpatches-fromthatwereoccasionallyusefulforbuildingagentsets.InNetLogo4.0,theseprimitiveshavebeenreplacedwithnewprimitivescalledturtle-setandpatch-setthataremuchmoreflexibleandpowerful.(link-setexistsaswell.)SeetheentriesfortheseprimitivesintheNetLogoDictionary.Modelsthatusetheoldturtles-fromandpatches-fromwillneedtobealteredbyhandtousethenewprimitives.

RGBColors

InNetLogo3.1RGBandHSBcolorscouldbeapproximatedasNetLogocolorsusingthergbandhsbprimitives.Thesehavebeenrenamedtoapproximate-rgbandapproximate-hsbandnowexpectinputsintherange0-255,not0-1.

ThefullRGBspectrumisnowavailableinNetLogosoitmaynolongerbenecessarytousetheseprimitivesatall.Youcansetanycolorvariabletoathree-itemRGBlist,withvaluesinthe0-255range,andgetthatexactcolor.SeetheColorsectionoftheProgrammingGuidefordetails.

Tie

Inpreviousversions__tiewasprovidedasanexperimentalfeature.AsofNetLogo4.0linkshaveatie-modevariablewhichcanbesetto"none","free",or"fixed".In4.0tieisnowalink-onlyprimitive.Thismeansthattotieturtle1toturtle0youwrite:

ask turtle 0 [ create-link-to turtle 1 [ tie ] ]

SeetheTiesectionoftheprogrammingguidefordetails.


Agentsets

Ifyourmodelisbehavingstrangelyorincorrectly,itmaybebecausesinceNetLogo3.1,agentsetsarenowalwaysinrandomorder.InpriorversionsofNetLogo,agentsetswerealwaysinafixedorder.Ifyourcodedependedonthatfixedorder,thenitwon'tworkanymore.Howtofixyourmodeltoworkwithrandomizedagentsetsdependsonthedetailsofwhatyourcodeisdoing.Insomesituations,itishelpfultousethesortorsort-byprimitivestoconvertanagentset(randomorder)intoalistofagents(fixedorder).See"Listsofagents"intheListssectionoftheProgrammingGuide.

Wrapping

Ifyouareseeingpiecesofturtleshapeswrappingaroundtheviewedges,it'sbecauseNetLogo3.0allowedyoutoturnoffsuchwrappingintheviewwithoutaffectingthebehaviorofthemodel.SinceNetLogo3.1,ifyoudon'twanttheviewtowrapyoumustmakeitsotheworlddoesn'twrap,usingthenewtopologyfeature.Makingthischangemayrequireotherchangestoyourmodel,though.SeetheTopologysectionoftheProgrammingGuideforathoroughdiscussionofhowtoconvertyourmodeltotakeadvantageofthisnewfeature.

Randomturtlecoordinates

ManymodelsmadeinNetLogo3.0orearlierusesetxy random world-width random world-heighttoscatterturtlesrandomly,usingeitherrandomorrandom-float.Itonlyworksifworldwrappingison.

(Why?Becausewhenwrappingison,youcansetcoordinatesofturtlestonumbersbeyondtheedgeoftheworldandNetLogowillwraptheturtletotheotherside.Butinworldsthatdon'twrapsettingthexorycoordinatesofaturtletoapointoutsidetheboundsoftheworldcausesaruntimeerror.TheworldwrapsettingswereaddedinNetLogo3.1.SeetheTopologysectionoftheProgrammingGuideformoreinformation.)

Tofixyourmodelsothatitworksregardlessofthewrappingsettings,useoneofthesetwocommandsinstead:

setxy random-xcor random-ycorsetxy random-pxcor random-pycor

Thetwocommandsareabitdifferent.Thefirstcommandputstheturtleonarandompointin

theworld.Thesecondcommandputstheturtleonthecenterofarandompatch.Anevenmoreconcisewaytoputaturtleonthecenterofarandompatchis:

move-to one-of patches

ShapesEditorGuide

TheTurtleandLinkShapeEditorsallowsyoutocreateandsaveturtleandlinkdesigns.

NetLogousesfullyscalableandrotatablevectorshapes,whichmeansyoucancreatedesignsbycombiningbasicgeometricelements,whichcanappearon-screeninanysizeororientation.

Gettingstarted

Tobeginmakingshapes,chooseTurtleShapesEditororLinkShapesEditorintheToolsmenu.Anewwindowwillopenlistingalltheshapescurrentlyinthemodel,beginningwithdefault,thedefaultshape.TheShapesEditorallowsyoutoeditshapes,createnewshapes,andborrowfromanothermodel.Youcanalsoimportturtleshapesfromalibraryofpre-existingshapes.

Importingshapes

EverynewmodelinNetLogostartsoffcontainingasmallcoresetoffrequentlyusedshapes.ManymoreturtleshapesareavailablebyusingtheImportfromlibrary...button.Thisbringsupadialogwhereyoucanselectoneormoreshapesandbringthemintoyourmodel.Selecttheshapes,thenpresstheImportbutton.

Similarly,youcanusetheImportfrommodel...buttontoborrowshapesfromanothermodel.

Defaultshapes

HerearetheturtleshapesthatareincludedbydefaultineverynewNetLogomodel:

Firstrow:default,airplane,arrow,box,bug,butterfly,carSecondrow:circle,circle2,cow,cylinder,dot,facehappy,faceneutralThirdrow:facesad,fish,flag,flower,house,leaf,lineFourthrow:linehalf,pentagon,person,plant,sheep,square,square2

Fifthrow:star,target,tree,triangle,triangle2,truck,turtleSixthrow:wheel,x

Shapeslibrary

Andherearetheshapesintheshapeslibrary(includingallofthedefaultshapes,too):

BydefaultthereisonlyoneLinkshapeinamodel,thatis"default".Thisshapeissimplyasinglestraightlinewithasimplearrowhead(ifthelinkhappenstobedirected).

Creatingandeditingturtleshapes

PressingtheNewbuttonwillmakeanewshape.Or,youmayselectanexistingshapeandpressEdit.

Tools

Intheupperleftcorneroftheeditingwindowisagroupofdrawingtools.Thearrowistheselectiontool,whichselectsanalreadydrawnelement.

Todrawanewelement,useoneoftheotherseventools:

Thelinetooldrawslinesegments.Thecircle,square,andpolygontoolscomeintwoversions,solidandoutline.

Whenusingthepolygontool,clickthemousetoaddanewsegmenttothepolygon.Whenyou'redoneaddingsegments,doubleclick.

Afteryoudrawanewelement,itisselected,soyoucanmove,delete,orreshapeitifyouwant:

Tomoveit,dragitwiththemouseTodeleteit,presstheDeletebutton.Toreshapeit,dragthesmall"handles"thatappearontheelementonlywhenitisselected.Tochangeitscolor,clickonthenewcolor.

Previews

Asyoudrawyourshape,youwillalsoseeitinfivesmallersizesinthefivepreviewareasfoundnearthebottomoftheeditingwindow.Thepreviewsshowyourshapeasitmightappearinyourmodel,includinghowitlooksasitrotates.Thenumberbeloweachpreviewisthesizeofthepreviewinpixels.Whenyouedittheview,patchsizeisalsomeasuredinpixels.Soforexample,thepreviewwith"20"belowitshowsyouhowyourshapewouldlookonaturtle(ofsize1)onpatchesofsize20pixels.

Therotatablefeaturecanbeturnedoffifyouwantashapethatalwaysfacesthesameway,regardlessoftheturtle'sheading.

Overlappingshapes

Newelementsgoontopofpreviouselements.YoucanchangethelayeringorderbyselectinganelementandthenusingtheBringtofrontandSendtobackbuttons.

Undo

AtanypointyoucanusetheUndobuttontoundotheedityoujustperformed.

Colors

ElementswhosecolormatchestheColorthatchanges(selectedfromadrop-downmenu--thedefaultisgray)willchangecoloraccordingtothevalueofeachturtle'scolorvariableinyourmodel.Elementsofothercolorsdon'tchange.Forexample,youcouldcreatecarsthatalwayshaveyellowheadlightsandblackwheels,butdifferentbodycolors.

Otherbuttons

The"RotateLeft"and"RotateRight"buttonsrotateelementsby90degrees.The"FlipHorizontal"and"FlipVertical"buttonsreflectelementsacrosstheaxes.

Thesefourbuttonswillrotateorfliptheentireshape,unlessanelementisselected,inwhichcaseonlythatelementisaffected.

Thesebuttonsareespeciallyhandyinconjunctionwiththe"Duplicate"buttonifyouwanttomakeshapesthataresymmetrical.Forexample,ifyouweremakingabutterfly,youcoulddrawthebutterfly'sleftwingwiththepolygontool,thenduplicatethewingwiththe"Duplicate"button,thenturnthecopyintoarightwingwiththe"FlipHorizontal"button.

Shapedesign

It'stemptingtodrawcomplicated,interestingshapes,butrememberthatinmostmodels,thepatchsizeissosmallthatyouwon'tbeabletoseeverymuchdetail.Simple,bold,iconicshapesareusuallybest.

Keepingashape

Whentheshapeisdone,giveitanameandpresstheDonebuttonatthebottomoftheeditingwindow.Theshapeanditsnamewillnowbeincludedinthelistofshapesalongwiththe"default"shape.

Creatingandeditinglinkshapes

Managinglinkshapesisverysimilartomanagingturtleshapes.So,youcancreateanewshapebypressingtheNewbuttonoryoucaneditexistingshapes.WhenyouaredoneeditingashapepressDoneifyouwanttokeepit.

Changinglinkshapeproperties

Thereareseveraldifferentpropertiesforeachlinkshapethatyouareallowedtochange:

Name-linkshapescanhavethesamenameasturtleshapesbutmustbeuniqueamonglinkshapes.DirectionIndicator-thedirectionindicator(thelittlearrowondirectedlinks)isjustliketheturtlevectorshapes,youcanedititusingthesameeditorbypressingtheEditbutton.Curviness-thisistheamountofbendinalinkexpressedinpatches(thisisparticularlyusefulifyouhavedirectedlinksgoinginbothdirectionssoyoucandiscernbothlinks)Numberoflines:Youcanhave1,2,or3linesineachlinkshape,youcontrolthisbyselectinglinepatternsinthe"leftline","middleline",and"rightline"selectionboxes.Dashpatternoflines:Thereareseveraldashedlinepatternsavailableintheselectionboxessonotalllinesneedbesolid.

Herearesomelinkshapeswithvariousproperties:

Usingshapesinamodel

Inthemodel'scodeorinthecommandcenter,youcanuseanyoftheshapesthatareinthemodel(thoughonlyturtlescanhaveturtleshapesandonlylinkscanhavelinkshapes).Forexample,supposeyouwanttocreate50turtleswiththeshape"rabbit".Providedthereissometurtleshapecalledrabbitinthismodel,givethiscommandtotheobserverinthecommandcenter:

observer> crt 50

Andthengivethesecommandstotheturtlestospreadthemout,thenchangetheirshape:

turtles> fd random 15turtles> set shape "rabbit"

Voila!Rabbits!Notetheuseofdoublequotesaroundtheshapename.Shapenamesarestrings.

Similarly,youcansettheshapevariableoflinks.Assumingthereisalinkshapecalled"road"inthismodel:

observer> crt 5 [ create-links-with other turtles ]turtles> fd 5links> set shape "road"

Theset-default-shapecommandisalsousefulforassigningshapestoturtlesandlinks.

BehaviorSpaceGuide

Thisguidehasthreeparts:

WhatisBehaviorSpace?:Ageneraldescriptionofthetool,includingtheideasandprinciplesbehindit.HowItWorks:Walksyouthroughhowtousethetoolandhighlightsitsmostcommonlyusedfeatures.AdvancedUsage:HowtouseBehaviorSpacefromthecommandline,orfromyourownJavacode.

WhatisBehaviorSpace?

BehaviorSpaceisasoftwaretoolintegratedwithNetLogothatallowsyoutoperformexperimentswithmodels.

BehaviorSpacerunsamodelmanytimes,systematicallyvaryingthemodel'ssettingsandrecordingtheresultsofeachmodelrun.Thisprocessissometimescalled"parametersweeping".Itletsyouexplorethemodel's"space"ofpossiblebehaviorsanddeterminewhichcombinationsofsettingscausethebehaviorsofinterest.

Ifyourcomputerhasmultipleprocessorcores,thenbydefault,modelrunswillhappeninparallel,onepercore.

WhyBehaviorSpace?

Theneedforthistypeofexperimentisrevealedbythefollowingobservations.Modelsoftenhavemanysettings,eachofwhichcantakearangeofvalues.Togethertheyformwhatinmathematicsiscalledaparameterspaceforthemodel,whosedimensionsarethenumberofsettings,andinwhicheverypointisaparticularcombinationofvalues.Runningamodelwithdifferentsettings(andsometimeseventhesameones)canleadtodrasticallydifferentbehaviorinthesystembeingmodeled.So,howareyoutoknowwhichparticularconfigurationofvalues,ortypesofconfigurations,willyieldthekindofbehavioryouareinterestedin?Thisamountstothequestionofwhereinitshuge,multi-dimensionparameterspacedoesyourmodelperformbest?

Forexample,supposeyouwantspeedysynchronizationfromtheagentsintheFirefliesmodel.Themodelhasfoursliders--number,cycle-length,flash-lengthandnumber-flashes--thathaveapproximately2000,100,10and3possiblevalues,respectively.Thatmeansthereare2000*100*10*3=600,000possiblecombinationsofslidervalues!Tryingcombinationsoneatatimeishardlyanefficientwaytolearnwhichonewillevokethespeediestsynchronization.

BehaviorSpaceoffersyouamuchbetterwaytosolvethisproblem.Ifyouspecifyasubsetofvaluesfromtherangesofeachslider,itwillrunthemodelwitheachpossiblecombinationofthosevaluesand,duringeachmodelrun,recordtheresults.Indoingso,itsamplesthemodel'sparameterspace--notexhaustively,butenoughsothatyouwillbeabletoseerelationshipsformbetweendifferentslidersandthebehaviorofthesystem.Afteralltherunsareover,adatasetisgeneratedwhichyoucanopeninadifferenttool,suchasaspreadsheet,database,orscientificvisualizationapplication,andexplore.

Byenablingyoutoexploretheentire"space"ofbehaviorsamodelcanexhibit,BehaviorSpacecanbeapowerfulassistanttothemodeler.

HowItWorks

TobeginusingBehaviorSpace,openyourmodel,thenchoosetheBehaviorSpaceitemonNetLogo'sToolsmenu.

Managingexperimentsetups

Thedialogthatopensletsyoucreate,edit,duplicate,delete,andrunexperimentsetups.Experimentsarelistedbynameandhowbymodelrunstheexperimentwillconsistof.

ExperimentsetupsareconsideredpartofaNetLogomodelandaresavedaspartofthemodel.

Tocreateanewexperimentsetup,pressthe"New"button.

Creatinganexperimentsetup

Inthenewdialogthatappears,youcanspecifythefollowinginformation.Notethatyoudon'talwaysneedtospecifyeverything;somepartscanbeleftblank,orleftwiththeirdefaultvalues,dependingonyourneeds.

Experimentname:Ifyouhavemultipleexperiments,givingthemdifferentnameswillhelpyoukeepthemstraight.

Varyvariablesasfollows:Thisiswhereyouspecifywhichsettingsyouwantvaried,andwhatvaluesyouwantthemtotake.Variablescanincludesliders,switches,choosers,andanyglobalvariablesinyourmodel.

Variablescanalsoincludemax-pxcor,min-pxcor,max-pycorandmin-pycor,world-width,world-heightandrandom-seed.Thesearenot,strictlyspeaking,variables,butBehaviorSpaceletsyouvarythemasiftheywere.Varyingtheworlddimensionsletsyouexploretheeffectofworldsizeuponyourmodel.Sincesettingworld-widthandworld-heightdoesnotnecessarilydefinetheboundsoftheworldhowtheyarevarieddependsonthelocationoftheorigin.Iftheoriginiscentered,BehaviorSpacewillkeepitcenteredsothevaluesworld-widthorworld-heightmustbeodd.Ifoneoftheboundsisatzerothatboundwillbekeptatzeroandtheotherboundwillmove,forexampleifyoustartwithaworldwithmin-pxcor = 0max-pxcor= 10andyouvaryworld-widthlikethis:

["world-width" [11 1 14]]

min-pxcorwillstayatzeroandmax-pxcorwillsetto11,12,and13foreachoftheruns.Ifneitheroftheseconditionsaretrue,theoriginisnotcentered,norattheedgeoftheworldyoucannotvaryworld-heightorworld-widthdirectlybutyoushouldvarymax-pxcor,max-pycor,min-pxcorandmin-pycorinstead.

Varyingrandom-seedletsyourepeatrunsbyusingaknownseedfortheNetLogorandomnumbergenerator.Notethatyou'realsofreetousetherandom-seedcommandinyourexperiment'ssetupcommands.Formoreinformationonrandomseeds,seetheRandomNumberssectionoftheProgrammer'sGuide.

Youmayspecifyvalueseitherbylistingthevaluesyouwantused,orbyspecifyingthatyouwanttotryeveryvaluewithinagivenrange.Forexample,togiveaslidernamednumbereveryvaluefrom100to1000inincrementsof50,youwouldenter:

["number" [100 50 1000]]

Or,togiveitonlythevaluesof100,200,400,and800,youwouldenter:

["number" 100 200 400 800]

Becarefulwiththebracketshere.Notethattherearefewersquarebracketsinthesecondexample.IncludingornotincludingthisextrasetofbracketsishowyoutellBehaviorSpacewhetheryouarelistingindividualvalues,orspecifyingarange.

Alsonotethatthedoublequotesaroundthevariablenamesarerequired.

Youcanvaryasmanysettingsasyouwant,includingjustone,ornoneatall.Anysettingsthatyoudonotvarywillretaintheircurrentvalues.Notvaryinganysettingsisusefulifyoujustwanttodomanyrunswiththecurrentsettings.

Whatorderyoulistthevariablesindetermineswhatordertherunswillbedonein.Allvaluesforalatervariablewillbetriedbeforemovingtothenextvalueforanearliervariable.Soforexampleifyouvarybothxandyfrom1to3,andxislistedfirst,thentheorderofmodelrunswillbe:x=1y=1,x=1y=2,x=1y=3,x=2y=1,andsoon.

Repetitions:Sometimesthebehaviorofamodelcanvaryalotfromruntorunevenifthesettingsdon'tchange,ifthemodelusesrandomnumbers.Ifyouwanttorunthemodelmorethanonceateachcombinationofsettings,enterahighernumber.

Measurerunsusingthesereporters:Thisiswhereyouspecifywhatdatayouwanttocollectfromeachrun.Forexample,ifyouwantedtorecordhowthepopulationofturtlesroseandfellduringeachrun,youwouldenter:

count turtles

Youcanenteronereporter,orseveral,ornoneatall.Ifyouenterseveral,eachreportermustbeonalinebyitself,forexample:

count frogs count mice count birds

Ifyoudon'tenteranyreporters,therunswillstilltakeplace.Thisisusefulifyouwanttorecordtheresultsyourselfyourownway,suchaswiththeexport-worldcommand.

Measurerunsateverystep:NormallyNetLogowillmeasuremodelrunsateverystep,usingthereportersyouenteredinthepreviousbox.Ifyou'redoingverylongmodelruns,youmightnotwantallthatdata.Uncheckthisboxifyouonlywanttomeasureeachrunafteritends.

Setupcommands:Thesecommandswillbeusedtobegineachmodelrun.Typically,youwillenterthenameofaprocedurethatsetsupthemodel,typicallysetup.Butitisalsopossibletoincludeothercommandsaswell.

Gocommands:Thesecommandswillberunoverandoveragaintoadvancetothemodeltothenext"step".Typically,thiswillbethenameofaprocedure,suchasgo,butyoumayincludeanycommandsyoulike.

Stopcondition:Thisletsyoudomodelrunsofvaryinglength,endingeachrunwhenacertainconditionbecomestrue.Forexample,supposeyouwantedeachruntolastuntiltherewerenomoreturtles.Thenyouwouldenter:

not any? turtles

Ifyouwantthelengthofrunstoallbeofafixedlength,justleavethisblank.

Therunmayalsostopbecausethegocommandsusethestopcommand,inthesamewaythatstopcanbeusedtostopaforeverbutton.Thestopcommandmaybeuseddirectlyinthegocommands,orinaprocedurecalleddirectlybythegocommands.(TheintentisthatthesamegoprocedureshouldworkbothinabuttonandinaBehaviorSpaceexperiment.)Notethatthestepinwhichstopisusedisconsideredtohavebeenaborted,sonoresultswillberecordedforthatstep.Therefore,thestoppingtestshouldbeatthebeginningofthegocommandsorprocedure,notattheend.

Finalcommands:Theseareanyextracommandsthatyouwantrunonce,whentherunends.Usuallythisisleftblank,butyoumightuseittocalltheexport-worldcommandorrecordtheresultsoftheruninsomeotherway.

Timelimit:Thisletsyousetafixedmaximumlengthforeachrun.Ifyoudon'twanttosetanymaximum,butwantthelengthoftherunstobecontrolledbythestopconditioninstead,enter0.

SpecialprimitivesforBehaviorSpaceexperiments

Currentlythereareonlytwo,behaviorspace-run-numberandbehaviorspace-experiment-name.TherunnumberreportedbytheformerprimitivematchestherunnumberusedintheresultsfilesgeneratedbyBehaviorSpace.Theexperimentnamereportedbythelattermatchesthenamewithwhichtheexperimentwassetup.

Runninganexperiment

Whenyou'redonesettingupyourexperiment,pressthe"OK"button,followedbythe"Run"button.Adialogtitled"Runoptions"willappear.

Runoptions:formats

Therunoptionsdialogletsyouselecttheformatsyouwouldlikethedatafromyourexperimentsavedin.Dataiscollectedforeachrunorstep,accordingtothesettingofMeasurerunsateverystepoption.Ineithercase,theinitialstateofthesystemisrecorded,afterthesetupcommandsrunbutbeforethegocommandsrunforthefirsttime.

Tableformatlistseachintervalinarow,witheachmetricinaseparatecolumn.Tabledataiswrittentotheoutputfileaseachruncompletes.Tableformatissuitableforautomatedprocessingofthedata,suchasimportingintoadatabaseorastatisticspackage.

Spreadsheetformatcalculatesthemin,mean,max,andfinalvaluesforeachmetric,andthenlistseachintervalinarow,witheachmetricinaseparatecolumn.Spreadsheetdataismore

human-readablethanTabledata,especiallyifimportedintoaspreadsheetapplication.

(Notehoweverthatspreadsheetdataisnotwrittentotheresultsfileuntiltheexperimentfinishes.Sincespreadsheetdataisstoredinmemoryuntiltheexperimentisdone,verylargeexperimentscouldrunoutofmemory.Soyoushoulddisablespreadsheetoutputunlessyoureallywantit.Ifyoudowantspreadsheetoutput,notethatifanythinginterruptstheexperiment,suchasaruntimeerror,runningoutofmemory,oracrashorpoweroutage,nospreadsheetresultswillbewritten.Forlongexperiments,youmaywanttoalsoenabletableformatasaprecautionsothatifsomethinghappensandyougetnospreadsheetoutputyou'llatleastgetpartialtableoutput.)

Afterselectingyouroutputformats,BehaviorSpacewillpromptyouforthenameofafiletosavetheresultsto.Thedefaultnameendsin".csv".Youcanchangeittoanynameyouwant,butdon'tleaveoffthe".csv"part;thatindicatesthefileisaCommaSeparatedValues(CSV)file.Thisisaplain-textdataformatthatisreadablebyanytexteditoraswellasbymostpopularspreadsheetanddatabaseprograms.

Runoptions:parallelruns

Therunoptionsdialogalsoletsyouselectwhetheryouwantmultiplemodelrunstohappeninparallel,andifso,howmanyareallowedtobesimultaneouslyactive.Thisnumberwilldefaulttothenumberofprocessorcoresinyourcomputer.

Thereareafewcautionsassociatedwithparallelruns.

First,ifmultiplerunsareactive,onlyoneofthemwillbeinthe"foreground"andcausetheviewandplotstoupdate.Theotherrunswillhappeninvisiblyinthebackground.

Second,invisiblebackgroundrunscan'tuseprimitivesthatonlyworkintheGUI.Forexample,abackgroundruncan'tmakeamovie.

Third,sinceparallelrunsprogressindependentlyofeachother,tableformatoutputmaycontaininterleaved,out-of-orderresults.Whenyouanalyzeyourtabledata,youmaywishtosortitbyrunnumberfirst.(Spreadsheetformatoutputisnotaffectedbythisissue,sinceitisnotwrittenuntiltheexperimentcompletesorisaborted.)

Fourth,usingallavailableprocessorcoresmaymakeyourcomputerslowtouseforothertaskswhiletheexperimentisrunning.

Fifth,doingrunsinparallelwillmultiplytheexperiment'smemoryrequirementsaccordingly.YoumayneedtoincreaseNetLogo'smemoryceiling(seethisFAQentry).

Observingruns

Afteryoucompletetherunoptionsdialog,anotherdialogwillappear,titled"RunningExperiment".Inthisdialog,you'llseeaprogressreportofhowmanyrunshavebeencompletedsofarandhowmuchtimehaspassed.Ifyouenteredanyreportersformeasuringtheruns,andifyouleftthe"Measurerunsateverystep"boxchecked,thenyou'llseeaplotofhowtheyvaryoverthecourseofeachrun.

YoucanalsowatchtherunsinthemainNetLogowindow.(Ifthe"RunningExperiment"dialogisintheway,justmoveittoadifferentplaceonthescreen.)Theviewandplotswillupdateasthemodelruns.Ifyoudon'tneedtoseethemupdate,thenusethecheckboxesinthe"RunningExperiment"dialogtoturntheupdatingoff.Thiswillmaketheexperimentgofaster.

Ifyouwanttostopyourexperimentbeforeit'sfinished,pressthe"Abort"button.Anyresults

generatedsofarwillstillbesaved.

Whenalltherunshavefinished,theexperimentiscomplete.

Advancedusage

Runningfromthecommandline

ItispossibletorunBehaviorSpaceexperiments"headless",thatis,fromthecommandline,withoutanygraphicaluserinterface(GUI).Thisisusefulforautomatingrunsonasinglemachineoraclusterofmachines.

NoJavaprogrammingisrequired.ExperimentsetupscanbecreatedintheGUIandthenrunlaterfromthecommandline,or,ifyouprefer,youcancreateoreditexperimentsetupsdirectlyusingXML.

Howtouseit

RunNetLogousingtheincludedcommandlinescript.ThisisfoundintherootdirectoryofyourNetLogoinstallationandisnamednetlogo-headless.shonMacandLinuxandnetlogo-headless.batonWindows.Thenetlogo-headlessscriptsupportsthefollowingarguments:

--model <path>:pathnameofmodeltoopen(required)--setup-file <path>:readexperimentsetupsfromthisfileinsteadofthemodelfile--experiment <name>:nameofexperimenttorun--table <path>:pathnametosendtableoutputto(or-forstandardoutput)--spreadsheet <path>:pathnametosendtableoutputto(or-forstandardoutput)--threads <number>:usethismanythreadstodomodelrunsinparallel,or1todisableparallelruns.defaultstoonethreadperprocessor.--min-pxcor <number>:overrideworldsizesettinginmodelfile--max-pxcor <number>:overrideworldsizesettinginmodelfile--min-pycor <number>:overrideworldsizesettinginmodelfile--max-pycor <number>:overrideworldsizesettinginmodelfile

--modelisrequired.Ifyoudon'tspecify--experiment,youmustspecify--setup-file.Bydefaultnoresultsaregenerated,soyou'llusuallywanttospecifyeither--tableor--spreadsheet,orboth.Ifyouspecifyanyoftheworlddimensions,youmustspecifyallfour.

Note:Theremainderofthisguideusesnetlogo-headless.shtorefertotheNetLogoHeadlesslaunchscript.IfyouareusingWindows,pleasesubstitutenetlogo-headless.batfornetlogo-headless.shineachexample.

Examples

ItiseasiestifyoucreateyourexperimentsetupaheadoftimeintheGUI,soitissavedaspartofthemodel.Torunanexperimentsetupsavedinamodel,hereisanexamplecommandline:

netlogo-headless.sh \ --model Fire.nlogo \ --experiment experiment1 \ --table -

Forthistowork,Java(version1.8orlater)mustbeavailable.YoucanmakeJavaavailabletoheadlessineitheroftwoways

1. SettheJAVA_HOMEenvironmentvariabletothepathtotheJavainstallation.ThisisthedirectoryoftheJavainstallationwhichcontainsa"bin"directory.

2. AddthedirectorycontainingtheJavaexecutabletothePATHenvironmentvariable

IfJAVA_HOMEisdefined,netlogo-headlesswillrunNetLogousingtheJavathatitpointsto,ignoringtheversionofJavaavailableonthepath.

Afterthenamedexperimenthasrun,theresultsaresenttostandardoutputintableformat,asCSV.("-"ishowyouspecifystandardoutputinsteadofoutputtoafile.)

Whenrunningnetlogoheadless,itforcesthesystempropertyjava.awt.headlesstobetrue.ThistellsJavatoruninheadlessmode,allowingNetLogotorunonmachineswhenagraphicaldisplayisnotavailable.

Therequired--modelargumentisusedtospecifythemodelfileyouwanttoopen.

The--experimentargumentisusedtospecifythenameoftheexperimentyouwanttorun.(AtthetimeyoucreateanexperimentsetupintheGUI,youassignitaname.)

Here'sanotherexamplethatshowssomeadditional,optionalarguments:

netloog-headless.sh \ --model Fire.nlogo \ --experiment experiment2 \ --max-pxcor 100 \ --min-pxcor -100 \ --max-pycor 100 \ --min-pycor -100

Notetheuseoftheoptional--max-pxcor,--max-pycor,etc.argumentstospecifyadifferentworldsizethanthatsavedinthemodel.(It'salsopossiblefortheexperimentsetuptospecifyvaluesfortheworlddimensions;iftheyarespecifiedbytheexperimentsetup,thenthereisnoneedtospecifythemonthecommandline.)

Sinceneither--tablenor--spreadsheetisspecified,noresultswillbegenerated.Thisisusefuliftheexperimentsetupgeneratesalltheoutputyouneedbysomeothermeans,suchasexportingworldfilesorwritingtoatextfile.

Yetanotherexample:

netlogo-headless.sh \ --model Fire.nlogo \ --experiment experiment2 \ --table table-output.csv \ --spreadsheet spreadsheet-output.csv

Theoptional--table <filename>argumentspecifiesthatoutputshouldbegeneratedinatableformatandwrittentothegivenfileasCSVdata.If-isspecifiedasthefilename,thantheoutputissenttothestandardsystemoutputstream.Tabledataiswrittenasitisgenerated,witheachcompleterun.

Theoptional--spreadsheet <filename>argumentspecifiedthatspreadsheetoutputshouldbegeneratedandwrittentothegivenfileasCSVdata.If-isspecifiedasthefilename,thantheoutputissenttothestandardsystemoutputstream.Spreadsheetdataisnotwrittenoutuntilallrunsintheexperimentarefinished.

Notethatitislegaltospecifyboth--tableand--spreadsheet,andifyoudo,bothkindsofoutputfilewillbegenerated.

HereisonefinalexamplethatshowshowtorunanexperimentsetupwhichisstoredinaseparateXMLfile,insteadofinthemodelfile:

netlogo-headless.sh \ --model Fire.nlogo \ --setup-file fire-setups.xml \ --experiment experiment3

IftheXMLfilecontainsmorethanoneexperimentsetup,itisnecessarytousethe--experimentargumenttospecifythenameofthesetuptouse.

InordertorunaNetLogo3Dexperiment,runheadlesswiththe--3Dargument,forexample:

netlogo-headless.sh \ --3D \ --model "Mousetraps 3D.nlogo3d" \ --experiment experiment1 \ --table -

Notethatyoushouldsupplya3Dmodelandtherearealso3Darguments--max-pzcor<number>and--min-pzcor <number>.

ThenextsectionhasinformationonhowtocreatestandaloneexperimentsetupfilesusingXML.

SettingupexperimentsinXML

Wedon'tyethavedetaileddocumentationonauthoringexperimentsetupsinXML,butifyoualreadyhavesomefamiliaritywithXML,thenthefollowingpointersmaybeenoughtogetyoustarted.

ThestructureofBehaviorSpaceexperimentsetupsinXMLisdeterminedbyaDocumentTypeDefinition(DTD)file.TheDTDisstoredinNetLogo.jar,assystem/behaviorspace.dtd.(JARfilesarealsozipfiles,soyoucanextracttheDTDfromtheJARusingJava's"jar"utilityorwithanyprogramthatunderstandszipformat.)

TheeasiestwaytolearnwhatsetupslooklikeinXML,though,istoauthorafewoftheminBehaviorSpace'sGUI,savethemodel,andthenexaminetheresulting.nlogofileinatexteditor.Theexperimentsetupsarestoredtowardstheendofthe.nlogofile,inasectionthatbeginsandendswithaexperimentstag.Example:

<experiments> <experiment name="experiment" repetitions="10" runMetricsEveryStep="true"> <setup>setup</setup> <go>go</go> <exitCondition>not any? fires</exitCondition> <metric>burned-trees</metric> <enumeratedValueSet variable="density"> <value value="40"/> <value value="0.1"/> <value value="70"/> </enumeratedValueSet> </experiment></experiments>

Inthisexample,onlyoneexperimentsetupisgiven,butyoucanputasmanyasyouwantbetweenthebeginningandendingexperimentstags.

BetweenlookingattheDTD,andlookingatexamplesyoucreateintheGUI,itwillhopefullybeapparenthowtousethetagstospecifydifferentkindofexperiments.TheDTDspecifieswhichtagsarerequiredandwhichareoptional,whichmayberepeatedandwhichmaynot,andsoforth.

WhenXMLforexperimentsetupsisincludedinamodelfile,itdoesnotbeginwithanyXMLheaders,becausenotthewholefileisXML,onlypartofit.Ifyoukeepexperimentsetupsintheirownfile,separatefromthemodelfile,thentheextensiononthefileshouldbe.xmlnot.nlogo,andyou'llneedtobeginthefilewithproperXMLheaders,asfollows:

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE experiments SYSTEM "behaviorspace.dtd">

Thesecondlinemustbeincludedexactlyasshown.Inthefirstline,youmayspecifyadifferentencodingthanUTF-8,suchasISO-8859-1.

AdjustingJVMParameters

OpeningtheNetLogoHeadlesslauncherscriptwillshowtheoptionsusedtolaunchjavawhenrunningNetLogoHeadless.YoucanadjustvariousJVMparametersinthisscript.YoumayalsopassinJavapropertiesstartingwith-Dtothelauncher.

Notetheuseof-Xmxtospecifyamaximumheapsizeofonegigabyte.Ifyoudon'tspecifyamaximumheapsize,youwillgetyourVM'sdefaultsize,whichmaybeunusablysmall.(Onegigabyteisanarbitrarysizewhichshouldbemorethanlargeenoughformostmodels;youcanspecifyadifferentlimitifyouwant.)

Notetheuseof-Dfile.encoding=UTF-8.ThisforcesallfileI/OtouseUTF-8encoding.DoingsoensuresthatNetLogocanloadallmodelsconsistently,andthatfile-*primitivesworkconsistentlyonallplatforms,includingmodelscontainingUnicodecharacters.

ControllingAPI

IfBehaviorSpaceisnotsufficientforyourneeds,apossiblealternativeistouseourControllingAPI,whichletsyouwriteJavacodethatcontrolsNetLogo.TheAPIletsyourunBehaviorSpaceexperimentsfromJavacode,or,youcanwritecustomcodethatcontrolsNetLogomoredirectlytodoBehaviorSpace-likethings.SeetheControllingsectionoftheUserManualforfurtherdetailsonbothpossibilities.

SystemDynamicsGuide

Thisguidehasthreeparts:

WhatistheSystemDynamicsModeler?:Ageneraldescriptionofthetool,includingtheideasandprinciplesbehindit.HowItWorks:Describestheinterfaceandhowyouuseit.Tutorial:Wolf-SheepPredation(aggregate):WalksyouthroughcreatingamodelwiththeSystemDynamicsModeler.

WhatistheNetLogoSystemDynamicsModeler?

SystemDynamicsisatypeofmodelingwhereyoutrytounderstandhowthingsrelatetooneanother.Itisalittledifferentfromtheagent-basedapproachwenormallyuseinNetLogomodels.

Withtheagent-basedapproachweusuallyuseinNetLogo,youprogramthebehaviorofindividualagentsandwatchwhatemergesfromtheirinteraction.InamodelofWolf-SheepPredation,forexample,youproviderulesforhowwolves,sheepandgrassinteractwitheachother.Whenyourunthesimulation,youwatchtheemergentaggregate-levelbehavior:forexample,howthepopulationsofwolvesandsheepchangeovertime.

WiththeSystemDynamicsModeler,youdon'tprogramthebehaviorofindividualagents.Instead,youprogramhowpopulationsofagentsbehaveasawhole.Forexample,usingSystemDynamicstomodelWolf-SheepPredation,youspecifyhowthetotalnumberofsheepwouldchangeasthetotalnumberofwolvesgoesupordown,andviceversa.Youthenrunthesimulationtoseehowbothpopulationschangeovertime.

TheSystemDynamicsModelerallowsyoutodrawadiagramthatdefinesthesepopulations,or"stocks",andhowtheyaffecteachother.TheModelerreadsyourdiagramandgeneratestheappropriateNetLogocode--globalvariables,proceduresandreporters--torunyourSystemDynamicsmodelinsideofNetLogo.

BasicConcepts

ASystemDynamicsdiagramismadeoffourkindsofelements:Stocks,Variables,FlowsandLinks.

AStockisacollectionofstuff,anaggregate.Forexample,aStockcanrepresentapopulationofsheep,thewaterinalake,orthenumberofwidgetsinafactory.

AFlowbringsthingsinto,oroutofaStock.Flowslooklikepipeswithafaucetbecausethefaucetcontrolshowmuchstuffpassesthroughthepipe.

AVariableisavalueusedinthediagram.ItcanbeanequationthatdependsonotherVariables,oritcanbeaconstant.

ALinkmakesavaluefromonepartofthediagramavailabletoanother.AlinktransmitsanumberfromaVariableoraStockintoaStockoraFlow.

TheSystemDynamicsModelerfiguresouthowthevalueofyourStockschangeovertimebyestimatingthemoverandover.Theestimationisn'talwaysperfect,butyoucanaffectitsaccuracybychangingthevalueofdt.Asdtdecreases,youestimatethemodelmorefrequently,soitgetsmoreaccurate.However,decreasingdtalsomakesthemodelslower.

SampleModels

TherearefourbasicmodelsintheSampleModelssectionoftheNetLogoModelsLibrarythatdemonstratetheuseoftheSystemDynamicsModeler.Allfourbasicmodelsexplorepopulationgrowth(and,inmodelswithpredation,populationdecline).

ExponentialGrowthandLogisticGrowtharesimpleexamplesofgrowthinonestock.

WolfSheepPredation(SystemDynamics)isanexampleofasystemwithmultiplestocksinfluencingoneanother.Itmodelsapredator-preyecosystemusingtheSystemDynamicsModeler.

WolfSheepPredation(DockedHybrid)isanexampleofamodelthatrunsboththeaSystemDynamicsmodelandanagent-basedmodelside-by-side.ItrunstheSystemDynamicsimplementationofWolf-SheepPredationnexttotheagent-basedWolfSheepPredationmodelfromtheBiologysectionofSampleModels.

HowitWorks

ToopentheSystemDynamicsModeler,choosetheSystemDynamicsModeleritemintheToolsmenu.TheSystemDynamicsModelerwindowwillappear.

DiagramTab

TheDiagramtabiswhereyoudrawyourSystemDynamicsdiagram.

Thetoolbarcontainsbuttonstoedit,deleteandcreateitemsinyourdiagram.

CreatingDiagramElements

ASystemDynamicsdiagramismadeupoffourkindsofcomponents:Stocks,Variables,FlowsandLinks.

Stock

TocreateaStock,presstheStockbuttoninthetoolbarandclickinthediagramareabelow.AnewStockappears.EachStockrequiresauniquename,whichbecomesaglobalvariable.StocksalsorequireanInitialvalue.Itcanbeanumber,avariable,acomplexNetLogoexpression,oracalltoaNetLogoreporter.

Variable

TocreateaVariable,presstheVariablebuttonandclickonthediagram.EachVariableintheSystemDynamicsModelrequiresauniquename,whichbecomesthenameofaprocedure,oraglobalvariable.VariablesalsorequireanExpression.Thisexpressioncanbeanumber,avariable,acomplexNetLogoexpression,oracalltoaNetLogoreporter.

Flow

TocreateaFlow,presstheFlowbutton.ClickandholdwhereyouwanttheFlowtobegin--eitheronaStockorinanemptyarea--anddragthemousetowhereyouwanttheFlowtoend--onaStockorinanemptyarea.EachFlowrequiresauniquename,whichbecomesaNetLogoreporter.FlowsrequireanExpression,whichistherateofflowfromtheinputtotheoutput.Thisexpressioncanbeanumber,avariable,acomplexNetLogoexpression,oracalltoaNetLogoreporter.Ifthevalueisnegative,theflowisintheoppositedirection.

WhenmorethanoneFlowisconnectedtoaStock,itisimportanttoconsiderhowtheyshouldinteractwithoneanother.NetLogowillnotenforcethattheFlowsoutofastockoccurinanyparticularorder.Also,NetLogowillnotensurethatthesumofFlowsoutofaStockarelessthanorequaltothevalueoftheStock.ThesebehaviorscanbeimplementedexplicitlywhencreatingtheExpressionforaFlow.

Forexample,iftheFlowisdefinedasaconstantvalue,10,youcanensureitneverdrawsmorethanthevalueoftheStockbyusingtheminprimitive:min (list stock 10).IfIwantFlowAtodepleteaStockbeforeFlowBiscalculated,IcanlinkFlowAtoFlowBandmodifyFlowBtosubtractFlowA'svaluefromthestock:min (list (max (list 0 (stock - flow-a))) 10).

Link

TocreateaLink,clickandholdonthestartingpointforthelink--aVariable,StockorFlow--anddragthemousetothedestinationVariableorFlow.

WorkingwithDiagramElements

WhenyoucreateaStock,Variable,orFlow,youseearedquestion-markontheelement.Thequestion-markindicatesthattheelementdoesn'thaveanameyet.TheredcolorindicatesthattheStockisincomplete:it'smissingoneormorevaluesrequiredtogenerateaSystemDynamicsmodel.Whenadiagramelementiscomplete,thenameturnsblack.

Selecting:Toselectadiagramelement,clickonit.Toselectmultipleelements,holdtheshiftkey.Youcanalsoselectoneormoreelementsbydraggingaselectionbox.

Editing:Toeditadiagramelement,selecttheelementandpressthe"Edit"buttononthetoolbar.Orjustdouble-clicktheelement.(YoucaneditStocks,FlowsandVariables,butyoucan'teditLinks).

Moving:Tomoveadiagramelement,selectitanddragthemousetoanewlocation.

Editingdt

Ontherightsideofthetoolbaristhedefaultdt,theintervalusedtoapproximatetheresultsofyourSystemDynamicsmodel.Tochangethevalueofthedefaultdtforyouraggregatemodel,presstheEditbuttonnexttothedtdisplayandenteranewvalue.

Errors

Whenyouclickthe"check"buttonorwhenyoueditastock,flow,orvariablethemodelerwillautomaticallygeneratetheNetLogocodethecorrespondstoyourdiagramandtrytocompilethatcode.IfthereisanerrortheCodetabwillturnredandamessagewillappear,andtheportionofthegeneratedcodethatiscausingthetroublewillbehighlighted.

Thisshouldgiveyouabetterideawhichelementinthediagramiscausingtheproblem.

CodeTab

TheSystemDynamicsModelergeneratesNetLogovariablesandproceduresbasedonthecontentsofyourdiagram.Theseproceduresarewhatmakethediagramactuallyperformcalculations.TheCodetabintheSystemDynamicsModelerwindowdisplaystheNetLogoproceduresgeneratedfromyourdiagram.

Youcan'teditthecontentsoftheCodetab.TomodifyyourSystemDynamicsmode,editthediagram.

Let'stakeacloserlookathowthegeneratedcoderelatestothediagram.:

StockscorrespondtoaglobalvariablethatisinitializedtothevalueorexpressionyouprovidedintheInitialvaluefield.EachStockwillbeupdatedeverystepbasedontheFlowsinandout.

FlowscorrespondtoaprocedurethatcontainstheexpressionyouprovidedintheExpressionfield.

Variablescaneitherbeglobalvariablesorprocedures.IftheExpressionyouprovidedisaconstantitwillbeaglobalvariableandinitializedtothatvalue.IfyouusedamorecomplicatedExpressiontodefinetheVariableitwillcreateaprocedurelikeaFlow.

ThevariablesandproceduresdefinedinthistabareaccessibleinthemainNetLogowindow,justlikethevariablesandproceduresyoudefineyourselfinthemainNetLogoCodetab.YoucancalltheproceduresfromthemainCodetab,fromtheCommandCenter,orfrombuttonsintheInterfacetab.Youcanrefertotheglobalvariablesanywhere,includinginthemainCodetabandinmonitors.

Therearethreeimportantprocedurestonotice:system-dynamics-setup,system-dynamics-go,andsystem-dynamics-do-plot.

system-dynamics-setupinitializestheaggregatemodel.Itsetsthevalueofdt,callsreset-ticks,andinitializesyourstocksandyourconverters.Converterswithaconstantvalueareinitializedfirst,followedbythestockswithconstantvalues.Theremainingstocksareinitializedinalphabeticalorder.

system-dynamics-gorunstheaggregatemodelfordttimeunits.ItcomputesthevaluesofFlowsandVariablesandupdatesthevalueofStocks.Italsocallstick-advancewiththevalueofdt.ConvertersandFlowswithnon-constantExpressionswillbecalculatedonlyoncewhenthisprocedureiscalled,however,theirorderofevaluationisundefined

system-dynamics-do-plotplotsthevaluesofStocksintheaggregatemodel.Tousethis,firstcreateaplotinthemainNetLogowindow.YouthenneedtodefineaplotpenforeachStockyouwanttobeplotted.Thisprocedurewillusethecurrentplot,whichyoucanchangeusingtheset-current-plotcommand.

TheSystemDynamicsModelerandNetLogo

ThediagramyoucreatewiththeSystemDynamicsModeler,andtheproceduresgeneratedfromyourdiagram,arepartofyourNetLogomodel.WhenyouasavetheNetLogomodel,yourdiagramissavedwithit,inthesamefile.

Tutorial:Wolf-SheepPredation

Let'screateamodelofWolf-SheepPredationwiththeSystemDynamicsModeler.

Step1:SheepReproduction

OpenanewmodelinNetLogo.LaunchtheSystemDynamicsModelerintheToolsmenu.

Ourmodelwillhaveapopulationofwolvesandapopulationofsheep.Let'sstartwiththesheep.First,createaStockthatholdsapopulationofSheep.

PresstheStockbuttoninthetoolbar.

Clickinthediagramarea.

YouseeaStockwitharedquestion-markinthemiddle.

Double-clicktheStocktoedit.NamethestocksheepSettheinitialvalueto100.DeselecttheAllowNegativeValuescheckbox.Itdoesn'tmakesensetohavenegativesheep!

Oursheeppopulationcanincreaseifnewsheepareborn.Toaddthistoourdiagram,wecreateaFlowintothestockofsheep.

ClickontheFlowbuttoninthetoolbarandpressthemousebuttoninanemptyareatotheleftofthesheepStock.DragtheFlowtotherightuntilitconnectstothesheepStockandletgo.EdittheFlowandnameitsheep-births.Fornow,enteraconstant,suchas1,intotheExpressionfield.

Thenumberofsheepbornduringaperiodoftimedependsonthenumberofsheepthatarealive:moresheepmeansmorereproduction.

DrawaLinkfromthesheepStocktothesheep-birthsFlow.

Therateofsheepbirthsalsodependsonsomeconstantfactorsthatarebeyondthescopeofthismodel:therateofreproduction,etc.

CreateaVariableandnameitsheep-birth-rate.Setitsvalueto0.04DrawaLinkfromthesheep-birth-rateVariabletothesheep-births.

Yourdiagramshouldlooksomethinglikethis:

Ourdiagramhasthecorrectstructurebutwearen'tyetfinishedbecauseittheamountofsheepflowingintothestockdoesn'tdependuponthenumberofsheepandsheepbirthrate.

Editthesheep-birthsFlowandsettheexpressiontosheep-birth-rate * sheep.

Wenowhaveacompletediagram.ToseetheNetLogocodegeneratedbyourdiagram,youcanclickontheCodetaboftheSystemDynamicsModelerwindow.Itlookslikethis:

Step2:NetLogoIntegration

OnceyoucreateanaggregatemodelwiththeSystemDynamicsModeler,youcaninteractwiththemodelthroughthemainNetLogointerfacewindow.Let'sbuildourNetLogomodeltorunthecodegeneratedbyourdiagram.We'llneedasetupandgobuttonswhichcallthesystem-dynamics-setupandsystem-dynamics-goprocedurescreatedbytheSystemDynamicsModeler.Andwe'llwantamonitorandaplottowatchthechangesinsheeppopulation.

SelectthemainNetLogowindowIntheCodetab,write:

to setup ca system-dynamics-setupend

to go system-dynamics-go system-dynamics-do-plotend

MovetotheInterfacetabCreateasetupbuttonCreateagobutton(don'tforgettomakeitforever)Createasheepmonitor.Createaplotcalled"populations"withapennamed"sheep".

Nowwe'rereadytorunourmodel.

Pressthesetupbutton.Don'tpressthe"go"buttonyet.Instead,typegofourorfivetimesintotheCommandCenter

Noticewhathappens.Thesheeppopulationincreasesexponentially.Afterfourorfiveiterations,wehaveanenormousnumberofsheep.That'sbecausewehavesheepreproduction,butoursheepneverdie.

Tofixthat,let'sfinishourdiagrambyintroducingapopulationofwolveswhicheatsheep.

Step3:WolfPredation

MovebacktotheSystemDynamicswindowAddastockofwolvesAddFlows,VariablesandLinkstomakeyourdiagramlooklikethis:

AddonemoreFlowfromthewolvesStocktotheFlowthatgoesoutoftheSheepstock.Fillinthenamesofthediagramelementssoitlookslikethis:

whereinitial-valueofwolvesis30,wolf-deathsiswolves * wolf-death-rate,wolf-death-rateis0.15,predator-efficiencyis.8,wolf-birthsiswolves * predator-efficiency * predation-rate * sheep,predation-rateis3.0E-4,andsheep-deathsissheep * predation-rate * wolves.

Adjustthedtofthesystemdynamicsmodelbyselecting"Edit"nexttodtinthetoolbarofthesystemdynamicsmodeler.Inthedialogthatappears,enter0.01.

Nowwe'rereallydone.

GobacktothemainNetLogowindowAddaplotpennamed"wolves"tothepopulationplotPresssetupandgotoseeyourSystemDynamicsModelerdiagraminaction.

Youseeaplotofthepopulationsthatlookslikethis:

HubNetGuide

ThissectionoftheUserManualintroducestheHubNetsystemandincludesinstructionstosetupandrunaHubNetactivity.

HubNetisatechnologythatletsyouuseNetLogotorunparticipatorysimulationsintheclassroom.Inaparticipatorysimulation,awholeclasstakespartinenactingthebehaviorofasystemaseachstudentcontrolsapartofthesystembyusinganindividualdevice,suchasanetworkedcomputer.

Forexample,intheGridlocksimulation,eachstudentcontrolsatrafficlightinasimulatedcity.Theclassasawholetriestomaketrafficflowefficientlythroughthecity.Asthesimulationruns,dataiscollectedwhichcanafterwardsbeanalyzedonacomputer.

Formoreinformationonparticipatorysimulationsandtheirlearningpotential,pleasevisittheParticipatorySimulationsProjectwebsite.

UnderstandingHubNet

NetLogo

NetLogoisaprogrammablemodelingenvironment.Itcomeswithalargelibraryofexistingsimulations,bothparticipatoryandtraditional,thatyoucanuseandmodify.Contentareasincludesocialscienceandeconomics,biologyandmedicine,physicsandchemistry,andmathematicsandcomputerscience.Youandyourstudentscanalsouseittobuildyourownsimulations.

IntraditionalNetLogosimulations,thesimulationrunsaccordingtorulesthatthesimulationauthorspecifies.HubNetaddsanewdimensiontoNetLogobylettingsimulationsrunnotjustaccordingtorules,butbydirecthumanparticipation.

SinceHubNetbuildsuponNetLogo,werecommendthatbeforetryingHubNetforthefirsttime,youbecomefamiliarwiththebasicsofNetLogo.TogetstartedusingNetLogomodels,seeTutorial#1:RunningModelsintheNetLogoUsersManual.

HubNetArchitecture

HubNetsimulationsarebasedonaclient/serverarchitecture.TheactivityleaderusestheNetLogoapplicationtorunaHubNetactivity.WhenNetLogoisrunningaHubNetactivity,werefertoitasaHubNetserver.ParticipantsuseaclientapplicationtologinandinteractwiththeHubNetserver.

WhileHubNetisonlysupportedviatheJavaDesktopclientsatthemoment,wehopetoaddsupportforothertypesofclientssuchastabletsandphonesinthefuture.

ComputerHubNet

Activities

ThefollowingactivitiesareavailableintheModelsLibrary,intheHubNetActivitiesfolder.InformationonhowtorunthemodelsandactivitiescanbefoundintheInfotabofeach

http://ccl.northwestern.edu/rp/ps/index.shtml

model.AdditionaldiscussionofeducationalgoalsandwaystoincorporatemanyoftheactivitiesintoyourclassroomintheParticipatorySimulationsGuideontheParticipatorySimulationsProjectwebsite.

BugHuntersCamouflage-studentshuntbugsandcamouflagingemerges.DiceStalagmiteHubNet-studentsrolldiceandexplorethespaceofdependentandindependentevents.Disease-Adiseasespreadsthroughthesimulatedpopulationofstudents.DiseaseDoctors-AslightmodificationtotheDiseaseactivitywheresomestudentscanrecoverfromthedisease.Gridlock-Studentsusetrafficlightstocontroltheflowoftrafficthroughacity.Polling-Askstudentsquestionsandplottheiranswers.RootBeerGame-AnadaptationofapopulargamecreatedatMITintheearly1960sthatshowshowsmalldelaysinadistributionsystemcancreatebigproblems.Sampler-Studentsengageinstatisticalanalysisasindividualsandasaclassroom.Throughtheseactivities,studentsdiscoverthemeaninganduseofbasicconceptsinstatistics.TragedyoftheCommons-Studentsworkasfarmerssharingacommonresource.

Clients

TousetheclientapplicationyousimplyneedtolaunchtheHubNetclientapplicationthatisbundledwithNetLogo.

Requirements

TouseComputerHubNet,youneedanetworkedcomputerwithNetLogoinstalledfortheserver.WhenusingtheclientapplicationyouwillalsoneedanetworkedcomputerwithNetLogoinstalledforeachparticipant.Whenusinginclassroomsettingswealsosuggestanattachedprojectorfortheleadertoprojecttheentiresimulationtotheparticipants.

Startinganactivity

You'llfindtheHubNetactivitiesinNetLogo'sModelsLibrary,intheHubNetActivitiesfolder.Wesuggestdoingafewpracticerunsofanactivitybeforetryingitinfrontofaclass.

OpenaComputerHubNetmodel.NetLogowillpromptyoutoenterthenameofyournewHubNetsession.Thisisthenamethatparticipantswillusetoidentifythisactivity.EnteranameandpressStart.

NetLogowillopentheHubNetControlCenter,whichletsyouinteractwiththeHubNetserver.

You,astheleader,shouldthennotifyeveryonethattheymayjoin.Tojointheactivity,

http://ccl.northwestern.edu/partsims.html

participantslaunchtheHubNetClientapplicationandentertheirname.TheyshouldseeyouractivitylistedandcanjoinyouractivitybyselectingitandpressingEnter.IftheactivityyoustartedisnotlistedthestudentcanentertheserveraddressmanuallywhichcanbefoundintheHubNetControlCenter.

HubNetControlCenter

TheHubNetControlCenterletsyouinteractwiththeHubNetserver.Itdisplaysthename,activity,addressandportnumberofyourserver.The"Mirror2DViewonclients"checkboxcontrolswhethertheHubNetparticipantscanseetheviewontheirclients,assumingthereisaviewintheclientsetup.The"Mirrorplotsonclients"checkboxcontrolswhetherparticipantswillreceiveplotinformation.

Theclientlistontherightdisplaysthenamesofclientsthatarecurrentlyconnectedtoyouactivity.Toremoveaparticipantfromtheactivity,selecttheirnameinthelistandpresstheKickbutton.TolaunchyourownHubNetclientpresstheLocalbutton,thisisparticularlyusefulwhenyouaredebugginganactivity.The"Reset"buttonkicksoutallcurrentlyloggedinclientsandreloadstheclientinterface.

ThelowerpartoftheControlCenterdisplaysmessageswhenaparticipantjoinsorleavestheactivity.Tobroadcastamessagetoalltheparticipants,clickonthefieldatthebottom,typeyourmessageandpressBroadcastMessage.

Troubleshooting

IstartedaHubNetactivity,butwhenparticipantsopenaHubNetClient,myactivityisn'tlisted.

Onsomenetworks,theHubNetClientcannotautomaticallydetectaHubNetserver.TellyourparticipantstomanuallyentertheserveraddressandportofyourHubNetserver,which

appearintheHubNetControlCenter.

Note:Thetechnicaldetailsonthisareasfollows.Inorderfortheclienttodetecttheserver,multicastroutingmustbeavailablebetweenthem.Notallnetworkssupportmulticastrouting.Inparticular,networksthatusetheIPsecprotocoltypicallydonotsupportmulticast.TheIPsecprotocolisusedonmanyvirtualprivatenetworks(VPNs).

Whenaparticipanttriestoconnecttoanactivity,nothinghappens(theclientappearstohangorgivesanerrorsayingthatnoserverwasfound).

Ifyourcomputerornetworkhasafirewall,itmaybeimpedingtheHubNetserverfromcommunicating.MakesurethatyourcomputerandnetworkarenotblockingportsusedbytheHubNetserver(ports9173-9180).

TheviewontheHubNetclientisgray.

Verifythatthe"Mirror2Dviewonclients"checkboxintheHubNetControlCenterisselected.Makesurethatthedisplayswitchinthemodelison.Ifyouhavemadechangestothesizeoftheviewontheserveryoumayneedtopressthe"Reset"buttonintheControlCentertoensuretheclientsgetthenewsize.

ThereisnoviewontheHubNetclient.

Someactivitiesdon'thaveaviewontheclient.Ifyouwanttoaddaviewsimplyselect"HubNetClientEditor"fromtheToolsMenuandaddaviewlikeanyotherwidget.Makesuretopressthe"Reset"buttonbeforehavingclientslogin.

Ican'tquitaHubNetclient.

Youwillhavetoforcetheclienttoquit.OnOSX,forcequittheapplicationbyselectingForceQuit...intheApplemenu.OnWindows,pressCtrl-Alt-DeletetoopentheTaskManager,selectHubNetClientandpressEndTask.

MycomputerwenttosleepwhilerunningaHubNetactivity.WhenIwokethecomputerup,IgotanerrorandHubNetwouldn'tworkanymore.

TheHubNetservermaystopworkingifthecomputergoestosleep.Ifthishappens,quittheNetLogoapplicationandstartover.Changethesettingsonyourcomputersoitwon'tsleepagain.

Myproblemisnotaddressedonthispage.

SeeContactingUs.

KnownLimitations

IfHubNetmalfunctions,seethebugreportinginformationatContactingUs.

Pleasenotethat:

HubNethasnotyetbeenextensivelytestedwithlargenumbersofclients(i.e.morethanabout25).Unexpectedresultsmayoccurwithmoreclients.Out-of-memoryconditionsarenothandledgracefullySendinglargeamountsofplottingmessagestotheclientscantakealongtime.NetLogodoesnothandlemaliciousclientsinarobustmanner(inotherwords,itislikelyvulnerabletodenial-of-servicetypeattacks).Performancedoesnotdegradegracefullyoversloworunreliablenetworkconnections.Ifyouareonawirelessnetworkorsub-LAN,theIPaddressintheHubNetControlCenterisnotalwaystheentireIPaddressoftheserver.ComputerHubNethasonlybeentestedonLANs,andnotondial-upconnectionsorWANs.

Teacherworkshops

ForinformationonupcomingworkshopsandNetLogoandHubNetuseintheclassroom,pleasecontactus.

HubNetAuthoringGuide

TolearnaboutauthoringormodifyingHubNetactivities,seetheHubNetAuthoringGuide.

RunningHubNetinheadlessmode

TolearnaboutrunningHubNetactivitiesfromthecommandline,withnoGUIontheserver,seetheHubNetsectionintheControllingGuide.

Gettinghelp

IfyouhaveanyquestionsaboutHubNetorneedhelpgettingstarted,contactus.

HubNetAuthoringGuide

ThisguideshowshowtounderstandandmodifythecodeofexistingHubNetactivitiesandwriteyourownnewones.ItassumesyouarefamiliarwithrunningHubNetactivities,basicNetLogocodeandNetLogointerfaceelements.FormoregeneralinformationaboutHubNetseetheHubNetGuide.

CodingHubNetactivitiesSetupReceivinginformationfromclientsSendinginformationtoclientsExamples

HowtomakeaclientinterfaceViewupdatesontheclientsClickingintheviewonclientsCustomizingtheclient'sviewPlotupdatesontheclients

CodingHubNetactivities

ManyHubNetactivitieswillsharebitsofthesamecode.Thatisthecodethatitusedtosetupthenetworkandthecodethatisusedtoreceiveinformationfromandsendinformationtotheclients.Ifyouunderstandthiscodeyoushouldbeabletoeasilymakemodificationstoexistingactivitiesandyoushouldhaveagoodstartonwritingyourownactivities.TogetyoustartedwehaveprovidedaTemplatemodel(inHubNetActivities->CodeExamples)thatcontainsthemostbasiccomponentsthatwillbeinthemajorityofHubNetactivities.Youshouldbeabletousethisactivityasastartingpointformostprojects.

CodeExample:Template

Setup

TomakeaNetLogomodelintoaHubNetactivityyoumustfirstinitializethenetwork.InmostHubNetactivitiesyouwillusethestartupproceduretoinitializethenetwork.startupisaspecialprocedurethatNetLogorunsautomaticallywhenyouopenanymodel.Thatmakesitagoodplacetoputcodethatyouwanttorunonceandonlyonce(nomatterhowmanytimestheuserrunsthemodel).ForHubNetweputthecommandthatinitializesthenetworkinstartupbecauseoncethenetworkissetupwedon'tneedtodosoagain.Weinitializethesystemusinghubnet-reset,whichwillasktheuserforasessionnameandopenuptheHubNetControlCenter.Hereisthestartupprocedureinthetemplatemodel:

to startup hubnet-resetend

Nowthatthenetworkisallsetupyoudon'tneedtoworryaboutcallinghubnet-resetagain.Takealookatthesetupprocedureinthetemplatemodel:

to setup cp cd clear-output

ask turtles [ set step-size 1 hubnet-send user-id "step-size" step-size ]end

Forthemostpartitlookslikemostothersetupprocedures,however,youshouldnoticethatitdoesnotcallclear-all.Inthismodel,andinthegreatmajorityofHubNetactivitiesintheModelsLibrary,wehaveabreedofturtlesthatrepresentthecurrentlyloggedinclients.Inthiscasewe'vecalledthisbreedstudents.Wheneveraclientlogsinwecreateastudentandrecordanyinformationwemightneedlateraboutthatclientinaturtlevariable.Sincewedon'twanttorequireuserstologoutandlogbackineverytimewesetuptheactivitywedon'twanttokillalltheturtles,instead,wewanttosetallthevariablesbacktoinitialvaluesandnotifytheclientsofanychangeswemake(moreonthatlater).

Receivingmessagesfromclients

DuringtheactivityyouwillbetransferringdatabetweentheHubNetclientsandtheserver.MostHubNetactivitieswillcallaprocedureinthegoloopthatchecksfornewmessagesfromclientsinthiscaseit'scalledlistenclients:

to listen-clients while [ hubnet-message-waiting? ] [ hubnet-fetch-message ifelse hubnet-enter-message? [ create-new-student ] [ ifelse hubnet-exit-message? [ remove-student ] [ execute-command hubnet-message-tag ] ] ]end

Aslongastherearemessagesinthequeuethisloopfetcheseachmessageoneatatime.hubnet-fetch-messagemakesthenextmessageinthequeuethecurrentmessageandsetsthereportershubnet-message-source,hubnet-message-tag,andhubnet-messagetotheappropriatevalues.Theclientssendmessageswhentheusersloginandlogoutanytimetheusermanipulatesoneoftheinterfaceelements,thatis,pushesabutton,movesaslider,clicksintheview,etc.Westepthrougheachmessageanddecidewhatactiontotakedependingonthetypeofmessage(enter,exit,orother),thehubnet-message-tag(thenameoftheinterfaceelement),andthehubnet-message-sourceofthemessage(thenameoftheclientthemessagecamefrom).

Onanentermessagewecreateaturtlewithauser-idthatmatchesthehubnet-message-sourcewhichisthenamethateachuserentersuponenteringtheactivity,itisguaranteedtobeunique.

to create-new-student create-students 1 [ set user-id hubnet-message-source set label user-id set step-size 1 send-info-to-clients ]end

Atthispointwesetanyotherclientvariablestodefaultvaluesandsendthemtotheclientsifappropriate.Wedeclaredastudents-ownvariableforeveryinterfaceelementontheclientthatholdsstate,thatis,anythingthatwouldbeaglobalvariableontheserver,sliders,choosers,switchesandinputboxes.Itisimportanttomakesurethatthesevariablesstaysynchronizedwiththevaluesvisibleontheclient.

Whentheclientslogouttheysendanexitmessagetotheserverwhichgivesyouachancetocleanupanyinformationyouhavebeenstoringabouttheclient,inthiscasewemerelyhavetoasktheappropriateturtletodie.

to remove-student ask students with [user-id = hubnet-message-source] [ die ]end

Allothermessagesareinterfaceelementsidentifiedbythehubnet-message-tagwhichisthenamethatappearsintheclientinterface.Everytimeaninterfaceelementchangesamessageissenttotheserver.Unlessyoustorethestateofthevaluescurrentlydisplayedintheclientinterfacewillnotbeaccessibleinotherpartsofthemodel.That'swhywe'vedeclaredastudents-ownvariableforeveryinterfaceelementthathasastate(sliders,switches,etc).Whenwereceivethemessagefromtheclientwesettheturtlevariabletothecontentofthemessage:

if hubnet-message-tag = "step-size"[ ask students with [user-id = hubnet-message-source] [ set step-size hubnet-message ]]

Sincebuttonsdon'thaveanyassociateddatathereisgenerallynoassociatedturtlevariable,insteadtheyindicateanactiontakenbytheclient,justaswitharegularbuttonthereisoftenprocedureassociatedwitheachbuttonthatyoucallwheneveryoureceiveamessageindicatingthebuttonhasbeenpressed.Thoughitiscertainlynotrequired,theprocedureisoftenaturtleprocedure,thatis,somethingthatthestudentturtleassociatedwiththemessagesourcecanexecute:

if command = "move left"[ set heading 270 fd 1 ]

Sendingmessagestoclients

Asmentionedearlieryoucanalsosendvaluestoanyinterfaceelementsthatdisplayinformation:monitors,sliders,switches,choosers,andinputboxes(notethatplotsandtheviewarespecialcasesthathavetheirownsections).

Therearetwoprimitivesthatallowyoutosendinformationhubnet-sendandhubnet-broadcast.Broadcastsendstheinformationtoalltheclients;sendsendstooneclient,oraselectedgroup.

Assuggestedearlier,nothingontheclientupdatesautomatically.Ifavaluechangesontheserver,itisyourresponsibilityastheactivityauthortoupdatemonitorsontheclient.

Forexample,sayyouhaveasliderontheclientcalledstep-sizeandamonitorcalledStepSize(notethatthenamesmustbedifferent)youmightwriteupdatingcodelikethis:

if hubnet-message-tag = "step-size"[ ask student with [ user-id = hubnet-message-source ] [ set step-size hubnet-message hubnet-send user-id "Step Size" step-size ]]

Youcansendanytypeofdatayouwant,numbers,strings,lists,listsoflists,listsofstrings,however,ifthedataisnotappropriateforthereceivinginterfaceelement(say,ifyouweretosendastringtoaslider)themessagewillbeignored.Hereareafewcodeexamplesfordifferenttypesofdata:

datatype hubnet-broadcastexample hubnet-sendexample

number hubnet-broadcast "A" 3.14 hubnet-send "jimmy" "A" 3.14

string hubnet-broadcast "STR1" "HI THERE"hubnet-send ["12" "15"] "STR1" "HITHERE"

listofnumbers hubnet-broadcast "L2" [1 2 3]

hubnet-send hubnet-message-source "L2"[1 2 3]

matrixofnumbers

hubnet-broadcast "[A]" [[1 2] [34]]

hubnet-send "susie" "[A]" [[1 2] [34]]

listofstrings

hubnet-broadcast "user-names"[["jimmy" "susie"] ["bob""george"]]

hubnet-send "teacher" "user-names"[["jimmy" "susie"] ["bob" "george"]]

Examples

Studythemodelsinthe"HubNetActivities"sectionoftheModelsLibrarytoseehowtheseprimitivesareusedinpracticeintheCodetab.Diseaseisagoodonetostartwith.

Howtomakeaclientinterface

OpentheHubNetClientEditor,foundintheToolsMenu.Addanybuttons,sliders,switches,monitors,plots,choosers,ornotesthatyouwantjustasyouwouldintheinterfacetab.You'llnoticethattheinformationyouenterforeachofthewidgetsisslightlydifferentthanintheInterfacepanel.Widgetsontheclientdon'tinteractwiththemodelinthesameway.Insteadofadirectlinktocommandsandreportersthewidgetssendmessagesbacktotheserverandthemodelthendetermineshowthosemessagesaffectthemodel.Allwidgetsontheclienthaveatagwhichisanamethatuniquelyidentifiesthewidget.Whentheserverreceivesamessagefromthatwidgetthetagisfoundinhubnet-message-tag

Forexample,ifyouhaveabuttoncalled"moveleft",aslidercalled"step-size",aswitchcalled"all-in-one-step?",andamonitorcalled"Location:",thetagsfortheseinterfaceelementswillbeasfollows:

interfaceelement tag

moveleft moveleftstep-size step-sizeall-in-one-step? all-in-one-step?

Location: Location:

Notethatyoucanonlyhaveoneinterfaceelementwithaspecificname.Havingmorethanoneinterfaceelementwiththesametagintheclientinterfacewillresultinunpredictablebehaviorsinceitisnotclearwhichelementyouintendedtosendtheinformationto.

Viewupdatesontheclients

Viewmirroringletsviewsoftheworldbedisplayedinclientsaswellontheserver.ViewmirroringisenabledusingacheckboxintheHubNetControlCenter.

Whenmirroringisenabled,clientviewsupdatewhenevertheviewontheserverdoes.Toavoidexcessivenetworktraffic,theviewshouldnotupdatemoreoftenthannecessary.Thereforewestronglyrecommendusingtick-basedupdates,ratherthancontinuousupdates.SeetheViewUpdatessectionoftheProgrammingGuideforanexplanationofthetwotypesofupdates.

Withtick-basedupdates,updateshappenwhenatickordisplaycommandruns.Werecommendusingthesecommandsonlyinsideaneveryblock,tolimitthefrequencyofviewupdatesandthusalsolimitnetworktraffic.Forexample:

every 0.1[ display]

IfthereisnoViewintheclientsoriftheMirror2DViewonClientscheckboxintheHubNetControlCenterisnotchecked,thennoviewupdatesaresenttotheclients.

Clickingintheviewonclients

IftheViewisincludedintheclient,twomessagesaresenttotheservereverytimetheuserclicksintheview.Thefirstmessage,whentheuserpressesthemousebutton,hasthetag"View".Thesecondmessage,sentwhentheuserreleasesthemousebutton,hasthetag"MouseUp".Bothmessagesconsistofatwoitemlistofthexandycoordinates.Forexample,toturnanypatchthatwasclickedonbytheclientred,youwouldusethefollowingNetLogocode:

if hubnet-message-tag = "View"[ ask patches with [ pxcor = (round item 0 hubnet-message) and pycor = (round item 1 hubnet-message) ] [ set pcolor red ]]

Customizingtheclient'sview

Whenviewmirroringisenabled,bydefaultclientsseethesameviewtheactivityleaderseesontheserver.Butyoucanchangethissothateachclientseessomethingdifferent,notjustaliteral"mirror".

Youcanchangewhataclientseesintwodistinctways.Wecallthem"clientperspectives"and"clientoverrides".

Changingaclient'sperspectivemeansmakingit"watch"or"follow"aparticularagent,much

likethewatchandfollowcommandsthatworkwithordinaryNetLogomodels.Seethedictionaryentriesforhubnet-send-watch,hubnet-send-follow,andhubnet-reset-perspective.

CodeExample:ClientPerspectiveExample

Clientoverridesletyouchangetheappearanceofpatches,turtles,andlinksintheclientviews.Youcanoverrideanyofthevariablesaffectinganagent'sappearance,includingthehidden?variablecausingaturtleorlinktobevisibleorinvisible.Seethedictionaryentriesforhubnet-send-override,hubnet-clear-override,andhubnet-clear-overrides.

CodeExample:ClientOverridesExample

Plotupdatesontheclients

Ifplotmirroringisenabled(intheHubNetControlCenter)andaplotintheNetLogomodelchangesandaplotwiththeexactsamenameexistsontheclients,amessagewiththatchangeissenttotheclientscausingtheclient'splottomakethesamechange.Forexample,let'spretendthereisaHubNetmodelthathasaplotcalledMilkSupplyinNetLogoandtheclients.MilkSupplyisthecurrentplotinNetLogoandintheCommandCenteryoutype:

plot 5

Thiswillcauseamessagetobesenttoalltheclientstellingthemthattheyneedtoplotapointwithayvalueof5inthenextpositionoftheplot.Notice,ifyouaredoingalotofplottingallatonce,thiscangeneratealotofplottingmessagestobesenttotheclients.

ModelingCommonsGuide

Introduction

TheModelingCommons(http://modelingcommons.org/)isaWeb-basedcollaborationsystemforNetLogomodelers.UsersoftheModelingCommonscanshare,download,modify,createvariationsof,commenton,andrunNetLogomodels--boththosethatareapartoftheNetLogomodelslibrary,andalsothosethathavebeenuploadedbyotherNetLogousers.

ByuploadingyourNetLogomodelstotheModelingCommons,youmakeiteasyforotherstosee,review,andcommentonyourwork.Youcanoptionallykeepthemodelprivate,eithertoyourselfortoagroupofyourchoice,ifyouaren'tcomfortablewithlettingeveryoneseethemodel.Youcanalwayschangethepermissionsassociatedwithamodel,ifyouchangeyourmindlateron.

NetLogonowmakesitpossibletosavemodelstotheModelingCommons,justasyoucansavethemto.nlogofilesonyourowncomputer.Youcanaccessthisfunctionalitybyselecting"UploadtoModelingCommons"fromthe"File"menu.

UseoftheModelingCommonsisfreeofcharge.Youmayuseitforyourownpersonalwork,foryourresearchgrouporcompany,orforaclassinwhichyouareastudentorteacher.TheModelingCommonsissponsoredbytheCCL,thesamegroupthatdevelopsanddistributesNetLogo.

ModelingCommonsAccounts

InordertouploadmodelstotheModelingCommons,youmustfirstbearegistereduser.Unregistereduserscanviewanddownloadmodels,butcannotupload,edit,orcommentonthem.

Thefirsttimethatyouinvoke"SavetoModelingCommons"inNetLogo,youwillbepromptedtoenteryoure-mailaddressandpassword.Ifyoualreadyhaveanaccount,thenyoucanenterthisinformationandclickonthe"Login"button.

Ifyoudon'tyethaveanaccountwiththeModelingCommons,thenyouwillneedtocreateone.Clickonthe"CreateAccount"button,andentertherequestedinformation.Onceyouhavedoneso,clickonthe"CreateAccount"button.Iftherearenoerrors,thenyouwillbepromptedtouploadaNetLogomodel.Alternatively,youmaygototheModelingCommonsitselfandregisterwithyourWebbrowser.

UploadingModels

http://modelingcommons.org/


TherearethreewaystouploadamodeltotheModelingCommons:Uploading,updating,andcreatingachild("forking").Thefollowingsectionsdescribetheseindetail.

UploadANewModel

AnewmodelwillbecreatedintheModelingCommons,withitsownpage,description,andforum.YoushouldusethisfunctionthefirsttimethatyousaveamodeltotheModelingCommons.

Youmustgiveyourmodelaname.Modelnamesarenotrequiredtobeunique;youcouldhave2ormoremodelswiththesamename,thoughwerecommendthatyounotdothis.

Bydefault,anyonecanview,fork,andupdateyourmodel.Youcanrestricttheabilitytoviewandforkyourmodelbychangingthevisibilitypermission.Youcanrestricttheabilitytoupdateyourmodelbychangingthechangeabilitypermission.Inordertosetpermissionsformultiplepeople,assignyourmodeltoagroup,andthenrestrictvisibilityorchangeabilitytomembersofthatgroup.GroupscanbecreatedfromtheModelingCommons.Onceyouhaveuploadedyourmodel,youcaneditthepermissionsfromthemodel'sModelingCommonspage.

Youcanoptionallyuploadapreviewimagetoyourmodel.ThepreviewimagewillbedisplayedalongsideyourmodelwheneveritisshownontheModelingCommons.Whileuploadingapreviewimageisoptional,wehighlyrecommendthatyoudoso,inoneofthefollowingthreeways:

The"Usecurrentimage"optiontellsNetLogotousethecurrentviewasyourpreview.Werecommendthatyoufirstrunthemodel,suchthatitshowsoffthekeyvisualfeatures.The"Auto-generateimage"featureauto-generatesapreviewimagebyrunningrandom-seed 0

http://modelingcommons.org/account/groups#group_tabs_new_group

setup repeat 75 [ go ].ThisoptionwillonlybeenabledifyouhavedefinedsetupandgoproceduresforNetLogotorun.The"Imagefromfile"featureallowsyoutouploadanyPNGimage.Previewimagesworkbestwhentheyaresquare.

UploadAChildOfAnExistingModel("forking")

Savingamodelinthisway,sometimesknownas"forking,"doesnotchangeoroverwritetheoriginalmodel.Rather,itcreatesanewmodelontheModelingCommons,muchasaplain"save"woulddo,simultaneouslycreatingaparent-childrelationshipbetweentheoldmodelandthenewone.Thisrelationshipcanbeseenonthe"family"tabforagivenmodel.Youmayforkanymodelforwhichyouhave"view"permissions,includingonethatyoucannotchange.Youmaywish,forexample,tocreateavariationonamodelintheNetLogomodelslibrary.

Toforkamodel,youmustgiveyournewchildaname,aswellasselectanexistingmodeltofork.Toindicatetheexistingmodel,starttypingthenameofthemodelthatyouwouldliketofork.Selectitsnamefromamongthesearchresults.

Finally,youmustenteradescriptionaboutwhatyouarechanginginyourchildmodel,andhowitrelatestoitsparent.

UpdatingAnExistingModel

UsethisoptionifyouhaveimprovedamodelthatalreadyexistsintheModelingCommons.Existing

attachments,discussions,andsocialtagswillbepreserved,butthemodelthatuserscandisplay,run,anddownloadwillbeupdated.Youmayonlyupdateamodelforwhichyouhave"write"permissions.

AllversionsofamodelaresavedintheModelingCommons,soyoushouldfeelfreetoexperimentwithnewideas.Ifsomethinggoeswrong,youcanalwaysrefertoanoldversionfromthe"history"tabonamodel'spage.

Toindicatewhichmodelshouldbeupdated,starttypingthenameofthemodel.Selectthenamethatpopsupwiththesearchresults.Finally,enteradescriptionaboutwhatyouarechanginginyournewversion.

Logging

NetLogo'sloggingfacilityallowsresearcherstorecordstudentactionsforlateranalysis.

LogginginNetLogo,onceinitiated,isinvisibletothestudent.Theresearchercanchoosethetypeofeventsloggedthroughaconfigurationfile.

NetLogousesthelog4jpackageforlogging.Ifyouhavepreviousexperiencewiththispackageyou'llfindlogginginNetLogofamiliar.

LoggingissupportedonlybythespecialNetLogoLoggingapplication.

Startinglogging

Thisdependsonwhatoperatingsystemyouareusing.

MacOSXorWindows

ThereisaspeciallogginglauncherintheNetLogodirectorycalledNetLogoLogging.Doubleclickontheicon.

OnWindows,theNetLogodirectorycanbefoundatC:\Program Files,unlessyouchoseadifferentlocationwhenyouinstalledNetLogo.

Linuxandothers

Toenablelogging,invokethenetlogo.shscriptasfollows:

netlogo.sh --logging netlogo_logging.xml

Youcouldalsomodifythescripttoincludetheseflags,orcopythescriptandmodifythecopy.

Youcanreplacenetlogo_logging.xmlwithanyvalidlog4jXMLconfigurationfile,whichwillbediscussedinmoredetaillater.

Usinglogging

WhenNetLogostartsupitwillaskforausername.Thisnamewillappearinallthelogsgeneratedduringthissession.

Wherelogsarestored

LogsarestoredintheOS-specifictempdirectory.OnmostUnix-likesystemsthatis/tmp.OnWindowsVistathelogscanbefoundinc:\Users\<user>\AppData\Local\Temp,where<user>istheloggedinuser.OnMacOSX,thetempdirectoryvariesforeachuser.YoucandetermineyourtempdirectorybyopeningtheTerminalapplicationandtypingecho $TMPDIRattheprompt.

Therearetwoconveniencecommandsthatwillhelpyoumanagethelogs.__zip-log-filesfilenamewillgatherallthelogsinthetempdirectoryandputtheminonezipfile,atthelocationspecified.Afterdoing__zip-log-filestheexistinglogsarenotdeleted,youcandoso

explicitlybyusing__delete-log-files.

Thefollowingisachartdescribingthenameoftheloggersavailable,thetypeofeventseachlogs,atwhatlevel,andprovidesasampleoutputusingtheXMLLayout.Alltheloggersarefoundinorg.nlogo.log.Logger.Whenreferringtotheloggersintheconfigurationfileyoushouldusethefullyqualifiedname.So,forexample,theloggerGLOBALSwouldactuallybeorg.nlogo.log.Logger.GLOBALS

Logger Events Level Example

GLOBALSaglobalvariablechanges

info,debug

<event logger="org.nlogo.log.Logger.GLOBALS" timestamp="1177341065988" level="INFO" type="globals"> <name>FOO</name> <value>51.0</value></event>

GREENS

sliders,switches,choosers,inputboxesarechangedthroughtheinterface

info

<event logger="org.nlogo.log.Logger.GREENS" timestamp="1177341065988" level="INFO" type="slider"> <action>changed</action> <name>foo</name> <value>51.0</value> <parameters> <min>0.0</min> <max>100.0</max> <inc>1.0</inc> </parameters></event>

CODE

codeiscompiled,including:commandcenter,Codetab,sliderbounds,andbuttons

info

<event logger="org.nlogo.log.Logger.CODE" timestamp="1177341072208" level="INFO" type="command center"> <action>compiled</action> <code>crt 1</code> <agentType>O</agentType> <errorMessage>success</errorMessage></event>

WIDGETS

awidgetisaddedorremovedfromtheinterface

info

<event logger="org.nlogo.log.Logger.WIDGETS" timestamp="1177341058351" level="INFO" type="slider"> <name></name> <action>added</action></event>

BUTTONSabuttonispressedorreleased

info

<event logger="org.nlogo.log.Logger.BUTTONS" timestamp="1177341053679" level="INFO" type="button"> <name>show 1</name> <action>released</action> <releaseType>once</releaseType>

</event>

SPEEDthespeedsliderchanges info

<event logger="org.nlogo.log.Logger.SPEED" timestamp="1177341042202" level="INFO" type="speed"> <value>0.0</value></event>

TURTLESturtlesdieorareborn info

<event logger="org.nlogo.log.Logger.TURTLES" timestamp="1177341094342" level="INFO" type="turtle"> <name>turtle 1</name> <action>born</action> <breed>TURTLES</breed></event>

LINKSlinksdieorareborn info

<event logger="org.nlogo.log.Logger.LINKS" timestamp="1177341094342" level="INFO" type="link"> <name>link 2 7</name> <action>born</action> <breed>LINKS</breed></event>

Howtoconfiguretheloggingoutput

Thedefaultloggingconfiguration(netlogo_logging.xml)lookssomethinglikethis:

NetLogodefines8loggers,alldescenddirectlyfromtherootlogger,whichmeansunlessyouexplicitlysettheproperties(appender,layout,andoutputlevel)intheconfigurationtheywillinheritthemfromtheroot.InthedefaultconfigurationtherootissettolevelINFO,theappenderisorg.nlogo.log.XMLFileAppenderandlayoutisorg.nlogo.log.XMLLayout.TogetherthesegenerateanicelyformattedXMLfileasdefinedinthenetlogo_logging.dtdwhichisbasedonthelog4jdtd.IftheappenderisaFileAppender(includingtheXMLFileAppender)anewfileisstarteachtimetheuseropensamodel.

<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">

<log4j:configuration debug="false" xmlns:log4j='http://jakarta.apache.org/log4j/'>

<appender name="A1" class="org.nlogo.log.XMLFileAppender"> <layout class="org.nlogo.log.XMLLayout"/> </appender>

<category name="org.nlogo.log.Logger.WIDGETS"> <priority value="off" /> </category>

<category name="org.nlogo.log.Logger.TURTLES"> <priority value="off" /> </category>

<category name="org.nlogo.log.Logger.LINKS">

<priority value="off" /> </category>

<root> <priority value ="info" /> <appender-ref ref="A1" /> </root>

</log4j:configuration>

Thisconfiguration,firstdefinesanappendernamed"A1"oftypeXMLFileAppenderwithanXMLLayout.Theappenderdefineswheretheloggingdatagoes,inthiscasethedatagoesintoafile.Infact,ifNetLogoisgivenaFileAppenderitwillautomaticallystartanewfileeverytimetheuseropensanewmodel.TheXMLFileAppenderalsodoessomeformattingandwritestheappropriateheaderstothefile.Thelayoutdefineshowtowriteeachindividualmessage.Unlessyouareanadvanceduserthereisnoneedchange(orworryabout)theappenderorthelayout.

Attheendoftheconfigurationnoticethedefinitionoftherootlogger.Alloftheotherloggersdescendfromtherootloggerand,thus,inheritthepropertiesoftherootunlessexplicitlyset.Thiscaseisfairlysimple,havingsetuptheappenderA1wemakethatthedefaultappenderfortheroot(andallotherloggers)andmakethedefaultpriority"INFO".MessagesthatareloggedattheINFOlevelorhigherwillbewritten,messagesloggedatlowerlevelswillnot.NotethatwithonlyoneexceptionNetLogoalwayslogsatlevelINFO.Setstoglobalsthatdon'tchangethevalueoftheglobalareloggedatlevelDEBUG.Whichmeansthatthesemessagesaredisabledbydefault,sincedebugislowerlevelthaninfo.Therestofthebodyoftheconfigurationfileoverridespropertiesoftherootloggerinafewspecificloggers(orcategoriesastheyareknownintheconfigurationfile,thetermscanbeassumedtobesynonymousfortheproposesofthisdocument).ThatisitturnsofftheWIDGET,TURTLES,andLINKSloggers,bydefault.Tore-enablethemyoucanchangesthepriorityfromofftoinfo,likethis:

<category name="org.nlogo.log.Logger.TURTLES"> <priority value="info" /> </category>

oryoucansimplyremovetheentirereferencetothecategoryfromtheconfigurationfile,asitisnotservinganyotherpurpose.

AdvancedConfiguration

ThisisonlyabasicintroductiontoconfigurationfilesforlogginginNetLogo.Therearemanymoreconfigurationoptionsavailablethroughthelog4jframework.Seethelog4jdocumentation.

https://logging.apache.org/log4j/1.2/manual.html

ControllingGuide

NetLogocanbeinvokedandcontrolledbyanotherprogramrunningontheJavaVirtualMachine.Forexample,youmightwanttocallNetLogofromasmallprogramthatdoessomethingsimplelikeautomateaseriesofmodelruns.Or,youmightwanttoembedNetLogomodelsinalargerapplication.

Formoreinformation,gohere.

https://github.com/NetLogo/NetLogo/wiki/Controlling-API

MathematicaLink

Whatisit?

TheNetLogo-Mathematicalinkprovidesmodelerswithaneasytouse,real-timelinkbetweenNetLogoandMathematica.Together,thesetoolscanprovideuserswithahighlyinteractive,self-documentingworkflowthatneithercanprovidealone.

Mathematicaincludesmanyofthetoolsthatagent-basedmodelersrelyonthroughouttheresearchprocess:advancedimportcapabilities,statisticalfunctions,datavisualization,anddocumentcreation.WiththeNetLogo-Mathematicalink,youcanrunallofthesetoolsside-by-sidewithNetLogo.

BecauseallMathematicadocuments,ornotebooks,containcomments,code,images,annotations,andinteractiveobjects,theintegrationofNetLogoandMathematicaprovidesamorecompletesolutionforcomplexmodelexplorationforstudentsandresearchersalike.

ThebasicfunctionalityofthelinkismuchliketheNetLogoControllingAPI:youcanloadmodels,executecommands,andreportbackdatafromNetLogo.UnliketheControllingAPI,whichisbasedonJava,allinteractionswiththelinkareinterpreted,makingitidealnotonlyforrapidlydesigningcustomBehaviorSpace-likeexperiments,butalsoasacompaniontoNetLogoindebuggingyourmodel.

FormoreinformationaboutMathematica,pleasevisittheWolframResearchwebsite.

WhatcanIdowithit?

HereareafewexamplesofwhatyoucandowiththeMathematica-NetLogolink.

Analyzeyourmodelinreal-timewithseamlesstwo-waydataconversionDevelophighquality,customvisualizationsofmodeldataCollectdetailedsimulationdataacrosslargemulti-dimensionalparameterspacesRapidlydevelopinteractiveinterfacesforexploringmodelbehaviorHavedirectaccesstopatchesandnetworkdatawithbuilt-infunctions

Installation

TheNetLogo-MathematicalinksupportsMathematica10orgreater.ToinstalltheNetLogo-Mathematicalink:

GotothemenubarinMathematicaClickonFileandselectInstall...IntheInstallMathematicaItemdialogSelectPackageforTypeofitemtoinstallClickSource,andselectFromfile...Inthefilebrowser,gotothelocationofyourNetLogoinstallation,clickontheMathematicaLinksubfolder,andselectNetLogo.m.ForInstallName,enterNetLogo.

YoucaneitherinstalltheNetLogolinkinyouruserbasedirectoryorinthesystem-widedirectory.IftheNetLogolinkisinstalledintheuserbasedirectory,otherusersonthesystemmustalsogothroughtheNetLogo-Mathematicalinkinstallationprocesstouseit.Thisoptionmightbepreferableifyoudonothavepermissiontomodifyfilesoutsideofyourhomedirectory.Otherwise,youcaninstallNetLogo-Mathematicalinkinthesystem-wide

http://www.wolfram.com/

Mathematicabasedirectory.

Usage

ThissectionwillverybrieflyintroducehowtousetheNetLogo-MathematicaLink.ItwillshowyouhowtoloadtheNetLogo-Mathematicalinkpackage,startNetLogo,executecommands,andretrievedatafromNetLogo.

Loadingthepackage:OncetheNetLogo-Mathematicalinkisinstalled,youcanloadthepackagebyenteringthefollowingintoyourMathematicanotebook:

<<NetLogo`

LaunchingNetLogofromMathematica:TobeginyourNetLogosessioninMathematica,typethefollowingintoyournotebook:

NLStart["your netlogo path"];

where"yournetlogopath"isthedirectorythatnetlogoislocatedin.TypicallyonaMacthiswillbe"/Applications/NetLogo6.0.2/"

Loadingamodel:Toloadamodel,youmustspecifythefullpathofthemodel.InthisexamplewewillloadtheForestFiremodel,andthepathwillbegivenusingthetypicalMacinstalllocation.

NLLoadModel["/Applications/NetLogo 6.0.2/models/Sample Models/EarthScience/Fire.nlogo"];

ExecutingaNetLogocommand:CommandscanbeexecutedbypassingastringofcommandstoNLCommand[].TheNLCommand[]functionautomaticallysplicescommonMathematicadatatypesintostringssuitableforNetLogo.Thefollowingcommandssetthedensityusingasinglestring,orsetthedensityusingaMathematicadefinedvariable,myDensity.

NLCommand["set density 50"]; myDensity = 60; NLCommand["set density", myDensity];

ReportinginformationfromNetLogo:NetLogodatacanbereportedbacktoMathematicausingNLReport[].Thisincludesnumbers,strings,booleanvalues,andlists.

NLReport["count turtles"]; NLReport["[(list pxcor pycor)] of n-of 10 patches"]

Formoreinformation,seetheNetLogo-MathematicaTutorialnotebookincludedwithNetLogo.Thenotebookwalksyouthroughtheprocessofusingthelink,withmanyexamplesalongtheway.IfyoudonothaveMathematica,butareconsideringusingthelink,youcanfindaPDFofthenotebookincludedwithNetLogointhe"MathematicaLink"directory.

KnownIssues

ANetLogosessioncannotbequitwithoutexitingJ/Link(theJava-Mathematicalink)entirely.ThismaydisruptotherpackagesthatmakeuseofJ/Link.IfamodelloadedwiththeNetLogo-MathematicalinkusesaNetLogoextension,theextensionmustbelocatedinthesamedirectoryasthemodelitself.IftheextensionislocatedinNetLogo'sapplication-wideextensionsdirectory,itwillnotbefound.CallstoNetLogo,suchasNLCommand[]andNLReport[],cannotbeaborted.

Sourcecode

ThesourcecodefortheNetLogo-Mathematicalinkisinthepublicdomain.Itishostedonlineathttps://github.com/NetLogo/Mathematica-Link.

Credits

TheprimarydeveloperoftheNetLogo-MathematicalinkwasEytanBakshy.

Torefertothispackageinacademicpublications,pleaseuse:Bakshy,E.,Wilensky,U.(2007).NetLogo-MathematicaLink.http://ccl.northwestern.edu/netlogo/mathematica.html.CenterforConnectedLearningandComputer-BasedModeling,NorthwesternUniversity,Evanston,IL.

https://github.com/NetLogo/Mathematica-Link

NetLogo3D

NetLogoincludestheNetLogo3Dapplicationthatallowsyoutocreate3Dworlds.

Notice:NetLogo'ssupportfor3DislessdevelopedthanNetLogo2D.Modelscreatedwiththisreleasemaynotbecompatiblewithfutureversions.Whilewe'vemadeeffortstoensureaqualityproduct,NetLogo3Dhasnotbeensubjecttothesamelevelofqualitycontrolasthemainapplication.

IntroductionTutorialDictionary

Introduction

TogetstartedusingNetLogo3D,launchtheNetLogo3DapplicationandcheckouttheSampleModelsinthe3DsectionoftheModelsLibrary.

Whenyou'rereadytowriteyourown3Dmodel,lookattheCodeExamplesinthe3DsectionoftheModelsLibrary.

CodeExample:TurtlePerspectiveExample3Dhelpsyoulearnaboutthedifferentperspectives.

CodeExample:TurtleandObserverMotionExample3Dhelpsyouunderstandhowturtlesandtheobservermovein3D.Youcanalsostepthroughthismodelwiththetutorialbelow.

3DWorlds

Anunspeakablehorrorseizedme.Therewasadarkness;thenadizzy,sickeningsensationofsightthatwasnotlikeseeing;IsawaLinethatwasnoLine;SpacethatwasnotSpace:Iwasmyself,andnotmyself.WhenIcouldfindvoice,Ishriekedloudinagony,"EitherthisismadnessoritisHell."

"Itisneither,"calmlyrepliedthevoiceoftheSphere,"itisKnowledge;itisThreeDimensions:openyoureyeonceagainandtrytolooksteadily."--EdwinA.Abbott,Flatland:Aromanceinmanydimensions

NetLogo3D'sworldhaswidth,heightanddepth.Patchesarecubes.Inadditiontopxcorandpycor,patcheshavepzcor.

TurtleshavethreeCartesiancoordinates,insteadoftwo,todescribeposition.Inadditiontoxcorandycor,turtleshavezcor.

Aturtle'sorientationisdefinedbythreeturtlevariables,heading,pitchandroll.Youcanimaginetheturtleashavingtwovectorstodefineitsorientationin3Dspace.Onevectorcomesstraightoutofthenoseoftheturtle,thisisthedirectiontheturtlewilltravelwhenitmovesforward.Thesecondvectorisperpendiculartotheforwardvectorandcomesoutoftherightsideoftheturtle(asiftheturtleweretostickitsrightarmstraightoutfromitsbody).Headingistheanglebetweentheforwardvectoroftheturtleprojectedontothexy-planeandthevector[010].Pitchistheanglebetweentheforwardvectoroftheturtleandthexy-planeandfinallyrollistheanglebetweentherightvectoroftheturtleandthexy-

plane.Whenturtleturnsrightorleftin3Dspaceitrotatesaroundthedownvector,thatisthevectorthatisperpendiculartoboththeforwardandrightvectors.Dependingontheorientationoftheturtlemorethanoneoftheinternalturtlevariablesmaychangeastheresultofaturn.

Theobserverandthe3Dview

Thepointofviewthatyouseetheworldfromisconsideredthelocationandorientationoftheobserver.Thisissimilartothe3DviewinNetLogo2D.However,thereareafewmorewaystocontroltheobserver.Youcansetthepointthattheobserverisfacingbyusingfaceandfacexyzwhichworkthesamewayastheturtlecommands,theobserverturnssothecenteroftheviewisonthegivenpointorthelocationofthegivenagentatthetimeitiscalled.Youcanchangethelocationoftheobserverusingsetxyz.Theobserverwillmovetoviewtheworldasifstandingonthegivenlocation,thepointtheobserverfaceswillstaythesame.Forexamplecreateanewmodelandobserverwillbelocatedat(0,0,49.5),thatis,onthez-axis49.5patchunitsawayfromtheoriginandtheobserverisfacingtheorigin,(0,0,0).Ifyousetxyz 0 49.5 0theobserverwillmovesoitisonthepositivey-axisbutitwillkeeptheoriginatthecenteroftheview.Youcanalsomovetheobserverusingtherotationprimitivesthatwillallowyoutomovetheobserveraroundtheworldasifonthesurfaceofaspherewherethecenteristhelocationtheobserverisfacing.Youmaynoticefromtheaboveexamplesthattheobserverisnotconstrainedtobewithintheboundsoftheworld.

CustomShapes

NetLogoautomaticallyinterprets2Dshapessotheyareextruded,likeacookiecuttershapeinthe3Dview.Youcanalsousetheprimitiveload-shapes-3dtoloadshapesdescribedinanexternalfileinacustomformatdescribedhere.Currentlywedonotimportshapesinanystandardformats.

Foreachshapeinacustom3Dshapefile,a2Dshapeofthesamenamemustexistaswell.Youcancreatethe2DshapeintheTurtleShapesEditor.

Theinputfilemaycontainanynumberofshapeswithanynumberofrectangularortriangularsurfaces.Theformatoftheinputfileshouldbeasfollows:

number of shapes in filename of first shapetype of surface ( quads or tris )surface1surface2...stoptype of surfacesurfaceA...stopend-shape

Eachsurfaceisdefinedbyaunitnormalvectorandtheverticeslistedinclockwiseorder,trisshouldhavethreeverticesandquadsshouldhavefour.

normal: xn yn znx1 y1 z1

x2 y2 z2x3 y3 z3x4 y4 z4

Afiledeclaringjustatwodimensional,patch-sized,squareinthexy-planecenteredattheoriginwouldlooklikethis:

1squarequadsnormal: 0 0 10.15 0.15 0-0.15 0.15 0-0.15 -0.15 00.15 -0.15 0normal: 0 0 -10.15 0.15 00.15 -0.15 0-0.15 -0.15 0-0.15 0.15 0stopend-shape

Tutorial

Step1:Depth

OneofthefirstthingsyouwillnoticewhenyouopenNetLogo3Disthattheworldisacubeinsteadofasquare.

YoucanopenuptheModelSettings,byclickingonthe"Settings..."buttonatthetopofthe3DView.You'llnoticeinadditiontomax-pxcor,min-pxcor,max-pycor,andmin-pycor,thereisalsomax-pzcorandmin-pzcor.

Thez-axisisperpendiculartoboththex-axisandthey-axis,whenyoureset-perspectiveitistheaxisthatcomesstraightoutofthescreen.Inthedefaultpositionmax-pzcoristhefaceofthecubenearesttoyouandmin-pzcoristhefacefarthestfromyou.Asalwaysmin-pxcorisontheleft,max-pxcorontheright,min-pycoronthebottom,andmax-pycoronthetop.

You'llalsonoticeontheleftsideoftheModelSettingsthatthereareoptionsforwrappinginallthreedirections,however,theyareallcheckedandgrayedout.TopologiesarenotyetsupportedinNetLogo3D,sotheworldalwayswrapsinalldimensions.

MovetotheCommandCenterandtypeprint count patches.

Isthenumbersmallerorlargerthanyouexpected?

Ina3Dworldthenumberofpatchesgrowsveryquicklysincecount patches = world-width * world-height * world-depth.It'simportanttokeepthisinmindwhenyouarebuildingyourmodel.LotsofpatchescanslowyourmodeldownorevencauseNetLogotorunoutofmemory.

Typeask patch 1 2 3 [ set pcolor red ] intotheCommandCenter.Usethemouseinthe3Dviewtorotatetheworld.

Noticetheshapeofthepatchanditspositioninrelationtotheedgesoftheworld.You'llalsonoticethatyounowneedthreecoordinatestoaddresspatchesina3Dworld.

Step2:TurtleMovement

OpentheModelsLibraryintheFilemenu.(IfyouareonaMacandyoudon'thaveaFilemenu,clickonthemainNetLogowindowfirstanditshouldreappear.)OpenTurtleandObserverMotionExample3Din3D/CodeExamples

Takeamomenttolookforthecontrolsandmonitors.Inthebottomleftyou'llnoticeagroupofmonitorsthatdescribethelocationandorientationoftheturtle,thoughuntilyoupressthesetupbuttonthey'llallsay"N/A".

Pressthe"setup"button

Heading,pitch,androllareturtlevariablesthatrepresenttheorientationoftheturtle.Headingisabsoluteinrelationtothex/yplane;itistherotationoftheturtlearoundthez-axis.

Pitchistheanglebetweenthenoseoftheturtleandthexy-plane.Itisrelativetoheading.

Rollistherotationaroundtheturtle'sforwardvector.Itisrelativetoheadingandpitch.

Whenturtlesarecreatedwithcreate-turtlesorcreate-ordered-turtles,theirinitialheadingsvarybuttheirinitialpitchandrollarealwayszero.

Takealookatthe"TurtleMovement"buttons.

Pressthe"left1"button.

Howdoestheturtlemove?Isisthesameordifferentfrom2DNetLogo?Whichoftheturtlevariableschange?

Pressthe"pitch-down1"button.

Howdoestheturtlemove?Whichoftheturtlevariableschange?

Pressthe"left1"buttonagain.

Howdoestheturtlemove?Isitdifferentthanthelasttimeyoupressedthe"left1"button?

TakealittletimetoplaywiththeTurtleMovementbuttons,watchingbothhowtheturtlemovesandwhichoftheturtlevariableschange.

Youprobablynoticedthatoftenmorethanoneoftheturtlevariablesmaychangeforasingleturn.Forthisreasonwesuggestthatyouusetheturtlecommandsratherthan

settingtheorientationvariablesdirectly.

Step3:ObserverMovement

AtthebottomoftheinterfaceyouwillseeOrbit,Zoom,andMovebuttons.Ifyouhaveeverusedthe3DviewinNetLogo2Dorifyouhavebeenusingthemousecontrolsinthe3Dviewthroughthistutorialyouhavebeenmovingtheobserver.Changingthepointofviewinthe3Dviewisactuallymovingandchangingtheorientationoftheobserver.Theobserverhasx,yandzcoordinates,justlikeaturtleorpatch,whileturtlesandpatchesareconstrainedtobeinsidetheworldtheobservercanbeanywhere.Likeaturtletheobserverhasaheading,pitchandroll,thesevariablescontrolwheretheobserverislooking,thatis,whatyouseeintheview.

Movetothe3Dview,andmakesure"Orbit"isselectedinthebottomleftcorneroftheview.Clickandholdthemousebuttoninthemiddleoftheview,movethemouseleft,right,up,anddown.

Howdoesthepositionandorientationoftheobserverchange?

Pressthereset-perspectivebuttoninthelowerrightcorneroftheviewandselect"Zoom"inthelowerleftcorner.Clickandholdthemousebuttoninthemiddleoftheviewandmovethemouseupanddown.

Whichoftheobservervariableschange?Whichstaythesame?

Tryrotatingtheworldabitandthenzoomagain.Pressthe"Move"buttoninthelowerleftcorneroftheview.Clickandholdthemousebuttoninthemiddleoftheviewandmovethemouseup,down,leftandright.

Howdoestheviewchange?Howdotheobservervariableschange?

Afteryouaredoneexploringtheworldusingthemousecontrolsyoucantakealookattheobservercontrolbuttonsinthelowerleftportionoftheinterface.

YoumayalreadybefamiliarwiththefirstthreebuttonsintheobservergroupfromyourexperiencewithNetLogo2D.Watch,follow,andride,arespecialmodesthatautomaticallyupdatethepositionandorientationoftheobserver.Wheninfolloworridemode,theobserverpositionandorientationarethesameastheturtle's.Notethatfollowandridearefunctionallyexactlythesame,thedifferenceisonlyvisualinthe3Dview.Wheninwatchmodetheobserverdoesnotmovebutupdatestofacethetargetagent.

Pressthe"setup"buttonagainsoyouarebacktothedefaultorientation.Pressthe"orbit-right"button.

Howdidtheviewchange?Wasitwhatyouexpected?Howisitsimilarordifferentfromusingthemousecontrols?

Takealittletimetoexperimentwithorbit,rollandzoombuttons;notice

similaritiesanddifferencestothemousecontrols.

Thedirectionoftheorbitcommandsrefertothedirectionthattheobservermoves.Thatis,imaginethattheobserverisonthesurfaceofasphere,thecenterofthesphereisthepointthattheobserverisfacingrepresentedbythebluecross,bydefault(0,0,0).Theobserverwillalwaysfacethecenterofthesphereandtheradiusofthespherewillremainconstant.Thedirections,up,down,left,andright,refertomovingalongthelinesoflatitudeandthelinesoflongitudeofthesphere.Whenyouzoomtheradiusofthespherechangesbutthecenterandtheobserver'sorientationinrelationtothecenterofthespherewillremainthesame.

Pressoneofthe"setxyz"buttons.


Pressthe"facexyz"button.


Whenyousetxyzthecenterofthesphereremainsthesame(sotheobserverautomaticallykeepsthatpointinthecenteroftheview.)However,theradiusofthespheremaychangeaswellastheobserver'sorientationinrelationtothecenter.Whenyoufacexyzorface,thecenterofthespherechangesbuttheobserverdoesnotmove.Theradiusofthespheremaychange,aswellastheorientationoftheobserver.

Dictionary

CommandsandReporters

Turtle-relatedprimitives

distancexyzdistancexyz-nowrapdzleftpatch-atpatch-at-heading-pitch-and-distancetilt-downtilt-uprightroll-leftroll-rightsetxyztowards-pitchtowards-pitch-nowraptowards-pitch-xyztowards-pitch-xyz-nowrapturtles-at

Patch-relatedprimitives

distancexyzdistancexyz-nowrapneighborsneighbors6patchpatch-atpatch-at-heading-pitch-and-distance

Agentsetprimitives

at-pointsbreeds-atturtles-at

Worldprimitives

Since4.1

Since4.1Since4.1

max-pzcormin-pzcorrandom-pzcorrandom-zcorworld-depthload-shapes-3d

Observerprimitives

facefacexyzorbit-downorbit-leftorbit-rightorbit-up__oxcor__oycor__ozcorsetxyzzoom

Linkprimitives

link-pitch

Built-InVariables

Turtles

zcorpitchroll

Patches

pzcor

Primitives

at-points

agentsetat-points[[x1y1z1][x2y2z2]...]

Reportsasubsetofthegivenagentsetthatincludesonlytheagentsonthepatchesthegivendistancesawayfromthisagent.Thedistancesarespecifiedasalistofthree-itemlists,wherethethreeitemsarethex,y,andzoffsets.

Ifthecalleristheobserver,thenthepointsaremeasuredrelativetotheorigin,inotherwords,thepointsaretakenasabsolutepatchcoordinates.

Ifthecallerisaturtle,thepointsaremeasuredrelativetotheturtle'sexactlocation,andnotfromthecenterofthepatchundertheturtle.

ask turtles at-points [[2 4 0] [1 2 1] [10 15 10]][ fd 1 ] ;; only the turtles on the patches at the ;; distances (2,4,0), (1,2,1) and (10,15,10), ;; relative to the caller, move

distancexyzdistancexyz-nowrap

distancexyzxcorycorzcordistancexyz-nowrapxcorycorzcor

Since4.1

Since4.1

Since4.1

3Dversionsofdistancexy.

Reportsthedistancefromthisagenttothepoint(xcor,ycor,zcor).

Thedistancefromapatchismeasuredfromthecenterofthepatch.

distancexyz-nowrapalwaysreportstheinworlddistance,neveradistancethatwouldrequirewrappingaroundtheedgesoftheworld.Withdistancexyzthewrappeddistance(aroundtheedgesoftheworld)isusedifthatdistanceisshorterthantheinworlddistance.

if (distancexyz 0 0 0) < 10 [ set color green ];; all turtles less than 10 units from;; the center of the screen turn green.

dz

dz

Reportsthez-increment(theamountbywhichtheturtle'szcorwouldchange)iftheturtleweretotakeonestepforwardatitscurrentheadingandpitch.

NOTE:dzissimplythesineoftheturtle'spitch.Bothdxanddyhavechangedinthiscase.So,dx=cos(pitch)*sin(heading)anddy=cos(pitch)*cos(heading).

Seealsodx,dy.

facefacexyz

faceagentfacexyzxyz

Setthecaller'sheadingandpitchtowardsagentortowardsthepoint(x,y,z).

Ifthecallerandthetargetareatthesamexandycoordinatesthecaller'sheadingwillnotchange.Ifthecallerandthetargetarealsoatthesamezcoordinatethepitchwillnotchangeeither.

left

leftnumber

Theturtleturnsleftbynumberdegrees,relativetoitscurrentorientation.Whileleftina2Dworldonlymodifiestheturtle'sheading,leftina3Dworldmayalsomodifytheturtle'spitchandroll.

Since4.1.2

Since4.1

Since4.1Since4.1

Since4.1Since4.1

Seealsoleft,tilt-up,tilt-down

link-pitch

link-pitch

Reportsthepitchfromend1toend2ofthislink.

ask link 0 1 [ print link-pitch ];; prints [[towards-pitch other-end] of end1] of link 0 1

Seealsolink-heading,pitch

load-shapes-3d

load-shapes-3dfilename

Loadscustom3Dshapesfromthegivenfile.Seethe3Dguideformoredetails.Youmustalsoadda2DshapeofthesamenametothemodelusingtheTurtleShapesEditor.Customshapesoverridebuilt-in3Dshapesandconverted2Dshapes.

max-pzcormin-pzcor

max-pzcormin-pzcor

Thesereportersgivethemaximumandminimumz-coordinates(respectively)forpatches,whichdeterminesthesizeoftheworld.

UnlikeinolderversionsofNetLogotheorigindoesnothavetobeatthecenteroftheworld.However,theminimumz-coordinatehastobelessthanorequalto0andthemaximumz-coordinatehastobegreaterthanorequalto0.

Note:Youcansetthesizeoftheworldonlybyeditingtheview--thesearereporterswhichcannotbeset.

Seealsomax-pxcor,max-pycor,min-pxcor,min-pycor,andworld-depth.

neighborsneighbors6

neighborsneighbors6

Since4.1Since4.1Since4.1Since4.1

Since4.1

3Dversionsofneighborsandneighbors4.

Reportsanagentsetcontainingthe26surroundingpatches(neighbors)or6surroundingpatches(neighbors6).

show sum values-from neighbors [count turtles-here] ;; prints the total number of turtles on the twenty-six ;; patches around this turtle or patchask neighbors6 [ set pcolor red ] ;; turns the six neighboring patches red

orbit-downorbit-leftorbit-rightorbit-up

orbit-downnumberorbit-leftnumberorbit-rightnumberorbit-upnumber

Rotatetheobserveraroundthelastpointfaced.Imaginetheobserverisonthesurfaceofasphere,thelastpointfaceisthecenterofthatsphere.Upanddownorbitalongthelinesoflongitudeandrightandleftorbitalongthelinesoflatitude.Theobserverwillremainfacingthelastpointfacedsotheheadingandpitchmaychangeasresultoforbiting.However,becauseweassumeanabsolutenorthpole(paralleltothepositivez-axis)therollwillneverchange.

Seealsosetxyz,faceandzoom

__oxcor__oycor__ozcor

__oxcor__oycor__ozcor

Reportsthex-,y-,orz-coordinateoftheobserver.

Seealsosetxyz

patch

patchpxcorpycorpzcor

3Dversionofpatch.

Since4.1

Since4.1

Giventhreeintegers,reportsthesinglepatchwiththegivenpxcor,pycorandpzcor.pxcor,pycorandpzcormustbeintegers.

ask (patch 3 -4 2) [ set pcolor green ];; patch with pxcor of 3 and pycor of -4 and pzcor of 2 turns green

Seealsopatch

patch-at

patch-atdxdydz

3Dversionofpatch-at.

Reportsthesinglepatchat(dx,dy,dz)fromthecaller,thatis,dxpatcheseast,dypatchesnorthanddzpatchesupfromthecaller.

ask patch-at 1 -1 1 [ set pcolor green ];; turns the patch just southeast and up from the caller green

patch-at-heading-pitch-and-distance

patch-at-heading-pitch-and-distanceheadingpitchdistance

3Dversionofpatch-at-heading-and-distance.

patch-at-heading-pitch-and-distancereportsthesinglepatchthatisthegivendistancefromthisturtleorpatch,alongthegivenabsoluteheadingandpitch.(Incontrasttopatch-left-and-aheadandpatch-right-and-ahead,thisturtle'scurrentheadingisnottakenintoaccount.)

ask patch-at-heading-pitch-and-distance 0 90 1 [ set pcolor green ];; turns the patch directly above the caller green.

pitch

pitch

Thisisabuilt-inturtlevariable.Pitchistheanglebetweenthe"nose"oftheturtleandthexy-plane.Headingandpitchtogetherdefinetheforwardvectoroftheturtleorthedirectionthattheturtleisfacing.

Thisisanumbergreaterthanorequalto0andlessthan360.0isparalleltothexy-plane,90isparalleltothez-axis.Whileyoucansetpitchwerecommendthatyouusetheprimitivestoturntheturtle.Dependingonthepositionmorethanonerelativeangle

Since4.1

Since4.1

(heading,pitchandroll)maychangeatonce.

Example:

;; assume roll and heading are 0set pitch 45 ;; turtle is now north and upset heading heading + 10 ;; same effect as "tilt-up 10"

Seealsoheading,roll,tilt-up,tilt-down,right,left

pzcor

pzcor

Thisisabuilt-inpatchvariable.Itholdsthezcoordinateofthepatch.Itisalwaysaninteger.Youcannotsetthisvariable,becausepatchesdon'tmove.

pzcorisgreaterthanorequaltomin-pzcorandlessthanorequaltomax-pzcor.

Allpatchvariablescanbedirectlyaccessedbyanyturtlestandingonthepatch.

Seealsopxcor,pycor,zcor.

random-pzcor

random-pzcor

Reportsarandomintegerrangingfrommin-pzcortomax-pxcorinclusive.

ask turtles [ ;; move each turtle to the center of a random patch setxyz random-pxcor random-pycor random-pzcor]

Seealsorandom-pxcor,random-pycor.

random-zcor

random-zcor

Reportsarandomfloatingpointnumberfromtheallowablerangeofturtlecoordinatesalongthezaxis.

Turtlecoordinatesrangefrommin-pzcor-0.5(inclusive)tomax-pzcor+0.5(exclusive).

ask turtles [ ;; move each turtle to a random point setxyz random-xcor random-ycor random-zcor]

Since4.1

Since4.1

Since4.1

Seealsorandom-xcor,random-ycor.

right

rightnumber

Theturtleturnsrightbynumberdegrees,relativetoitscurrentorientation.Whilerightina2Dworldonlymodifiestheturtle'sheading,rightina3Dworldmayalsomodifytheturtle'spitchandroll.

Seealsorightandleft

roll

roll

Thisisabuilt-inturtlevariable.Rollistheanglebetweenthe"wing-tip"oftheturtleandthexy-plane.

Thisisanumbergreaterthanorequalto0andlessthan360.Youcansetthisvariabletomakeaturtleroll.Sincerollisalwaysfromtheturtle'spointofview,rollingrightandleftonlyonlychangerollregardlessofturtleorientation.

Example:

set roll 45 ;; turtle rotated rightset roll roll + 10 ;; same effect as "roll-right 10"

Seealsoheading,pitch,roll-left,roll-right.

roll-left

roll-leftnumber

Thewingtipoftheturtlerotatestotheleftnumberdegreeswithrespecttothecurrentheadingandpitch.

roll-right

roll-rightnumber

Thewingtipoftheturtlerotatestotherightnumberdegreeswithrespecttothecurrentheadingandpitch.

Since4.1

Since4.1Since4.1

Since4.1Since4.1

setxyz

setxyzxyz

3Dversionofsetxy.

Theagent,aturtleortheobserver,setsitsx-coordinatetox,itsy-coordinatetoyanditsz-coordinatetoz.Whentheobserverusessetxyzitremainsfacingthesamepointsotheheading,pitch,androll,mayalsochange.

Forturtlesequivalenttoset xcor x set ycor y set zcor z,exceptithappensinonetimestepinsteadofthree.

setxyz 0 0 0;; agent moves to the middle of the center patch

Seealsoface

tilt-downtilt-up

tilt-downnumbertilt-upnumber

Thenoseoftheturtlerotatesbynumberdegrees,relativetoitscurrentorientation.Dependingontheorientationoftheturtlemorethanoneoftherelativeangles(heading,pitch,androll)maychangewhenaturtleturns.

towards-pitchtowards-pitch-nowrap

towards-pitchagenttowards-pitch-nowrapagent

Reportsthepitchfromthisagenttothegivenagent.

Ifthewrappeddistance(aroundtheedgesofthescreen)isshorterthantheon-screendistance,towards-pitchwillreportthepitchofthewrappedpath.towards-pitch-nowrapneverusesthewrappedpath.

Note:Inordertogetoneturtletofaceanotheryouneedtousebothtowards-pitchandtowards.

Note:askingforthepitchfromanagenttoitself,oranagentonthesamelocation,willcausearuntimeerror.

Seealsotowards

Since4.1Since4.1

Since4.1

Since4.1

towards-pitch-xyztowards-pitch-xyz-nowrap

towards-pitch-xyzxyztowards-pitch-xyz-no-wrapxyz

Reportsthepitchfromthisagenttothecoordinatesx,y,z

Ifthewrappeddistance(aroundtheedgesofthescreen)isshorterthantheon-screendistance,towards-pitchwillreportthepitchofthewrappedpath.towards-pitch-nowrapneverusesthewrappedpath.

Note:Inordertogetaturtletofaceagivenlocationyouneedtousebothtowards-pitch-xyzandtowardsxy.

Note:askingforthepitchfromanagenttothelocationitisstandingonwillcausearuntimeerror.

Seealsotowardsxy

turtles-at<breeds>-at

turtles-atdxdydz<breeds>-atdxdydz

3Dversionsofturtles-atandbreeds-at.

Reportsanagentsetcontainingtheturtlesonthepatch(dx,dy,dz)fromthecaller(includingthecalleritselfifit'saturtle).

;; suppose I have 40 turtles at the originshow [count turtles-at 0 0 0] of turtle 0=> 40

world-depth

world-depth

ReportsthetotaldepthoftheNetLogoworld.

Thedepthoftheworldisthesameasmax-pzcor-min-pzcor+1.

Seealsomax-pzcor,min-pzcor,world-width,andworld-height

zcor

dictionary.htnl#turtles-at

Since4.1

zcor

Thisisabuilt-inturtlevariable.Itholdsthecurrentzcoordinateoftheturtle.Thisisafloatingpointnumber,notaninteger.Youcansetthisvariabletochangetheturtle'slocation.

Thisvariableisalwaysgreaterthanorequalto(-screen-edge-z)andstrictlylessthanscreen-edge-z.

Seealsosetxy,xcor,ycor,pxcor,pycor,pzcor

zoom

zoomnumber

Movetheobservertowardthepointitisfacing,numbersteps.Theobserverwillnevermovebeyondthepointitisfacingsoifnumberisgreaterthanthedistancetothatpointitwillonlymoveasfarasthepointitisfacing.

ExtensionsGuide

NetLogoallowsuserstowritenewcommandsandreportersinJavaandotherlanguagesandusethemintheirmodels.ThissectionoftheUserManualintroducesthisfacilityandshowshowtouseanextensioninyourmodelonceyouhaveobtainedormadeone.

ExtensionscreatedbymembersoftheNetLogocommunityareavailablefromhttps://github.com/NetLogo/NetLogo/wiki/Extensions.

Forinformationoncreatingyourownextensions,gohere.

UsingExtensions

Touseanextensioninamodel,addtheextensionskeywordatthebeginningoftheCodetab,beforedeclaringanybreedsorvariables.

Afterextensionscomesalistofextensionnamesinsquarebrackets.Forexample:

extensions [sound speech]

UsingextensionstellsNetLogotofindandopenthespecifiedextensionandmakesthecustomcommandsandreportersfoundintheextensionavailabletothecurrentmodel.Youcanusethesecommandsandreportersjustasiftheywerebuilt-inNetLogoprimitives.

Whereextensionsarelocated

NetLogowilllookforextensionsinseveralplaces:

1. Inthefolderofthecurrentmodel.2. TheextensionsfolderlocatedwiththeNetLogoinstallation.FortypicalNetLogo

installations:OnMacOSX:/Applications/NetLogo 6.0.2/extensionsOn64-bitWindowswith64-bitNetLogoor32-bitWindowswith32-bitNetLogo:C:\Program Files\NetLogo 6.0.2\app\extensionsOn64-bitWindowswith32-bitNetLogo:C:\Program Files (x86)\NetLogo6.0.2\app\extensionsOnLinux:theapp/extensionssubdirectoryoftheNetLogodirectoryextractedfromtheinstallation.tgz

EachNetLogoextensionconsistsofafolderwiththesamenameastheextension,entirelyinlowercase.ThisfoldermustcontainaJARfilewiththesamenameasthefolder.Forexamplethesoundextensionisstoredinafoldercalledsoundwithafileinsidecalledsound.jar.

ToinstallaNetLogoextensionforusebyanymodel,puttheextension'sfolderintheNetLogoextensionsdirectory.Or,youcanjustkeeptheextension'sfolderinthesamefolderasthemodelthatusesit.

Someextensionsdependonadditionalfiles.Thesefileswillbeintheextension'sfolderalongwiththeJARfile.Thefoldermayalsocontainotherfilessuchasdocumentationandexamplemodels.

https://github.com/NetLogo/NetLogo/wiki/Extensions

https://github.com/NetLogo/NetLogo/wiki/Extensions-API

NetLogoArduinoExtension

Using

Forafirstusewithoutcompilingcode,dothefollowing:

1. AcquiretheNetLogosoftware.TheArduinoextensioncomespre-installedwithNetLogo5.2.1andlater.

2. AcquireanArduinoboardandinstallthearduinoIDE

3. UsetheArduinoIDEtoedittheSketch(ifdesired)andsendtotheboard.(Seeelaboratecommentsinthesketchforrecommendationsaboutwhattocommentout/leaveindependingonyoursetup&circuitontheboard.)

4. OncetheArduinohasthesketchloadedonit,itwillrunthatsketchwheneveritispoweredon.

5. Openthetest“ArduinoExample”modelintheNetLogoModelslibrary(it’sinthe“IABMTextbook”>“Chapter8”folder)

6. ConnecttheArduinotoaUSBportonthecomputerifitisnotstillconnectedfromstep3.

7. PressOPENtochoosetheporttocommunicatewithandestablishtheconnection.

8. Usethebuttonstosendbytecommands;usetheinterfacetoinspectvariablevalue(s)thatyoursketchissending.

9. Notethatbytypingarduino:primitivesyoucangetalistoftheavailablecommandsintheextension.

Notes

ANetLogomodelusingthisextensionmustworkinconjunctionwithanArduinoSketch.Thesetwoendpointscommunicatebywayofanapplicationprotocolthattheydefine.Forexample,iftheNetLogomodelsendsabyte‘1’overthewirethismaymeansomethingtotheArduinoSketch,whichwillrespondaccordingly.TheArduinoSketchforitsownpartmaysendname-valuepairsovertheserialport,whichthencanbelookedupasynchronouslybytheNetLogomodel.

Themodelerisfreetobuildassimpleorascomplexanapplicationprotocolontopofthisrawcommunicationmechanism.

Theasynchronousnatureoftheboard-to-computercommunicationshasonenotablelimitation.Ifyouchoosetotrytosimulateasynchronous,BLOCKINGREADcommunicationspattern,(e.g.,bysendingabyte-basedsignaltotheboard,whichtriggersaresponseinaknownname-valuepair),thenyouarelikelytobe‘offbyone’response.Thatis,ifyoudothefollowinginNetLogocode:

arduino:write-byte bshow arduino:get "varname"

YouarelikelytogetthevalueofvarnamefromthePRIORcommandrepresentedby

http://ccl.northwestern.edu/netlogo/download.shtml

writingthebyteb.ThisisbecausethesecondlineofNetLogocodewillexecutewhiletheArduinoisoffgeneratinganewvalueforvarname.

Therearewaysofgettingaroundthis(simulatingablockinginterfacebypollingonavaluetoindicatefresh“news”onvarname).ButthisextensionworksbestinsettingswheretheArduinoSketchis“chatty”andtheNetLogomodelsamplesthisstreamwhenitneedsdata.

Compatibility

ThiscodehasbeentestedonWindows7and10with32-bitNetLogoandonMacOSX.Youarelikelytoencounterissueswhenrunningthiswith64-bitNetLogoinWindows8orWindows10,soifyouhaveWindows8or10,pleasedownloadthe32-BitversionofNetLogoifyouplanonusingtheArduinoextension.Westriveforcross-platformcompatibilityacrossMac,Win,andLinux.Soifyouhavetroubles,pleaseletusknow.

Questions

Ifyourunintoproblemsorhavequestionsabouttheextension,[email protected].

Primitives

arduino:primitivesarduino:portsarduino:openarduino:closearduino:getarduino:write-stringarduino:write-intarduino:write-bytearduino:is-open?

arduino:primitives

arduino:primitives

Reportsalistofprimitivesavailableintheextension,withbasichintsabouttheirsyntax.

arduino:ports

arduino:ports

Reportsalistofportnames

arduino:open

arduino:openport-name

Openstheportnamedport-name.

arduino:close

arduino:close

Closesthecurrentlyopenport.



arduino:get

arduino:getvar-name

Readsandreportsthevalueassociatedwithvar-nameontheArduinoboard.Note:var-nameiscaseinsensitive.

arduino:write-string

arduino:write-stringstring-message

Writesastringmessagetothecurrentlyopenport.

arduino:write-int

arduino:write-intint-message

Writesaintegermessagetothecurrentlyopenport.

arduino:write-byte

arduino:write-bytebyte-message

Writesabytemessagetothecurrentlyopenport.

arduino:is-open?

arduino:is-open?

Reportsabooleanvalue(trueorfalse)indicatingifaportisopen.

NetLogoArrayExtension

Using

Thearrayextensionispre-installedinNetLogo.

Tousethearrayextensioninyourmodel,addalinetothetopofyourCodetab:

extensions [array]

Ifyourmodelalreadyusesotherextensions,thenitalreadyhasanextensionslineinit,sojustaddarraytothelist.

FormoreinformationonusingNetLogoextensions,seetheExtensionsGuide

WhentoUse

Ingeneral,anythingyoucandowithanarrayinNetLogo,youcouldalsojustusealistfor.Butyoumaywanttoconsiderusinganarrayinsteadforspeedreasons.Listsandarrayshavedifferentperformancecharacteristics,soyoumaybeabletomakeyourmodelrunfasterbyselectingtheappropriatedatastructure.

Arraysareusefulwhenyouneedacollectionofvalueswhosesizeisfixed.Youcanquicklyaccessoralteranyiteminanarrayifyouknowitsposition.

UnlikeNetLogo’slistsandstrings,arraysare“mutable”.Thatmeansthatyoucanactuallymodifythemdirectly,ratherthanconstructinganalteredcopyaswithlists.Ifthearrayisusedinmorethanoneplaceinyourcode,anychangesyoumakewillshowupeverywhere.It’strickytowritecodeinvolvingmutablestructuresandit’seasytomakesubtleerrorsorgetsurprisingresults,sowesuggeststickingwithlistsandstringsunlessyou’recertainyouwantandneedmutability.

ExampleuseofArrayExtension

let a array:from-list n-values 5 [0]print a=> {{array: 0 0 0 0 0}}print array:length a=> 5foreach n-values 5 [ i -> i ] [ i -> array:set a i i * i ]print a=> {{array: 0 1 4 9 16}}print array:item a 0=> 0print array:item a 3=> 9array:set a 3 50print a=> {{array: 0 1 4 50 16}}

Primitives

array:from-listarray:itemarray:setarray:lengtharray:to-list

array:from-list

array:from-list

array:from-listlist

Reportsanewarraycontainingthesameitemsinthesameorderastheinputlist.

array:item

array:itemarrayindex

Reportstheiteminthegivenarraywiththegivenindex(rangingfromzerotothelengthofthearrayminusone).

array:set

array:setarrayindexvalue

Setstheiteminthegivenarraywiththegivenindex(rangingfromzerotothelengthofthearrayminusone)tothegivenvalue.

Notethatunlikethereplace-itemprimitiveforlists,anewarrayisnotcreated.Thegivenarrayisactuallymodified.

array:length

array:lengtharray

Reportsthelengthofthegivenarray,thatis,thenumberofitemsinthearray.

array:to-list

array:to-listarray

Reportsanewlistcontainingthesameitemsinthesameorderasthegivenarray.

NetLogoBitmapExtension

Using

Thebitmapextensionispre-installedinNetLogo.Forinstructionsonusingit,orformoreinformationaboutNetLogoextensions,seetheNetLogoUserManual.

WhatdoestheBitmapExtensiondo?

TheBitmapExtensionallowsyoutomanipulateandimportimagesintothedrawingandpatches.ItoffersfeaturesnotprovidedbytheNetLogocoreprimitives,suchas:scaling,manipulationofdifferentcolorchannels,andwidthandheightreporters.

Gettingstarted

ToimportandmanipulateimagesyouwillneedtoincludethebitmapextensioninyourNetLogomodel.

extensions[ bitmap ]

TheimagefileformatssupportedaredeterminedbyyourJavavirtualmachine’simageiolibrary.TypicallythisisPNG,JPG,GIF,andBMP.PNGisagood,standardchoicethatislikelytoworkeverywhere.

Iftheimageformatsupportstransparency(alpha),thatinformationwillbeimportedaswell.

Primitives

bitmap:average-colorbitmap:channelbitmap:copy-to-drawingbitmap:copy-to-pcolorsbitmap:difference-rgbbitmap:exportbitmap:from-viewbitmap:to-grayscalebitmap:heightbitmap:importbitmap:scaledbitmap:width

bitmap:average-color

bitmap:average-colorimage

Reportsa3-elementlistdescribingtheamountofR,G,andBinimage,bysummingacrossallpixels,andnormalizingeachcomponentbythenumberofpixelsintheimage,soeachcomponentrangesfrom0to255.

bitmap:channel

bitmap:channelimagechannel

Extractseitherthealpha,red,green,orbluechannelfromanimage.Theinputchannelshouldbeaninteger0-3indicatingthechanneltoremove(alpha=0,red=1,green=2,blue=3).Theresultingimageisagrayscaleimagerepresentingspecifiedchannel.

bitmap:copy-to-drawing

bitmap:copy-to-drawingimagexy

Importsthegivenimageintothedrawingwithoutscalingtheimageatthegivenpixelcoordinates.

bitmap:copy-to-pcolors

bitmap:copy-to-pcolorsimageboolean

Importsthegivenimageintothepcolors,scaledtofittheworld.ThesecondinputindicateswhetherthecolorsshouldbeinterpretedasNetLogocolorsorleftasRGBcolors.falsemeansRGBcolors.

bitmap:difference-rgb

bitmap:difference-rgbimage1image2

Reportsanimagethatistheabsolutevalueofthepixel-wiseRGBdifferencebetweentwoimages.Notethatimage1andimage2MUSTbethesamewidthandheightaseachother,orerrorswillensue.

bitmap:export

bitmap:exportimagefilename

Writesimagetofilename.

bitmap:from-view

bitmap:from-view

Reportsanimageofthecurrentview.

bitmap:to-grayscale

bitmap:to-grayscaleimage

Convertsthegivenimagetograyscale.

bitmap:height

bitmap:heightimage

Reportstheheightofgivenimage

bitmap:import

bitmap:importfilename

ReportsaLogoBitmapcontainingtheimageatfilename.

bitmap:scaled

bitmap:scaledimagewidthheight

Reportsanewimagethatisimagescaledtothegivenwidthandheight

bitmap:width

bitmap:widthimage

Reportsthewidthofthegivenimage

NetLogoCfExtension

Using

TheCFextensioncurrentlyincludesprimitivesthatallowyoutodothingssimilartoif-elseif-elsechainsyouseeinotherlanguages,aswellasthingssimilartoswitchesinotherlanguages.However,itdoesitinamoreflexiblewaythanmanylanguages.Afewquickexamplestogetyoustarted:

let x 5let y 7cf:whencf:case [ x > y ] [ print "x is bigger than y!" ]cf:case [ x < y ] [ print "x is less than y!" ]cf:else [ print "x is the same as y!" ]

let my-awesome-number 5cf:match my-awesome-numbercf:case [ [n] -> n > 7 ] [ print "The number is greater than 7!" ]cf:case [ [n] -> n < 3 ] [ print "The number is less than 3!" ]cf:else [ print "The number is somewhere in between 3 and 7!" ]

Cases

Centraltothisextensionistheconceptofacase.Acaseissimplyalistoftwoelements,wherethefirstelementisareporterandthesecondelementiseitherareporteroracommand.Thefirstelement,calledthecondition,mustreporteithertrueorfalse.Thesecondargumentiscalledtheconsequent.Ifyou’recuriousabouthowCFworks,keepreadingthissection.Otherwise,feelfreetoskiptothelistofprimitives;youdon’tneedtounderstandtheinternalstostartusingCF.

AlmostallprimitivesintheCFextensiontakealistofcasesasanargument.Typically,theygothroughthecases,lookingforatruecondition.Whentheyfindone,theythenruntheconsequent.AlthoughCFprovidesprimitivesthatmakeconstructingalistofcaseseasy,youcouldactuallyjustbuildsuchalistwithprimitivesalreadyinNetLogo,likeso:

let x 5let y 7let list-of-cases (list (list task [ x > y ] task [ print "x is greater than y!" ]) (list task [ x < y ] task [ print "x is less than y!" ]) (list task [ true ] task [ print "x is the same as y!" ]))

However,thisisnotverynicelooking.WithCF,youcanwriteitlikethisinstead:

let x 5let y 7

let list-of-casescf:case [ x > y ] [ print "x is greater than y!" ]cf:case [ x < y ] [ print "x is less than y!" ]cf:else [ print "x is the same as y!" ]

Primitives

cf:whencf:selectcf:matchcf:matchingcf:casecf:case-iscf:else

cf:when

cf:whenlist-of-cases

Runsthecommandtaskfromthefirstcaseinthelistwithatruecondition.Forinstance:

let x 3cf:whencf:case [ x < 2 ] [ print "x is less than 2!" ]cf:case [ x < 4 ] [ print "x is less than 4!" ]cf:case [ x < 6 ] [ print "x is less than 6!" ]cf:else [ print "x is greater than or equal to 6!" ]

Theabovecodewillprintoutx is less than 4! sincethat’sthefirstcasewithatruecondition.

Ifnotruecaseisfound,andnocf:elsegiven,cf:whenwillerrorwithasuggestionforafix.

cf:select

cf:selectlist-of-cases

Picksthefirstcaseinthelistwithatrueconditionandreportstheresultofitsconsequent.Theconsequentsofthecasesinacf:selectmustbereportertasks.Thus,cf:selectisexactlylikecf:when,exceptthatitreportsthevaluefromthetruecase,ratherthanjustrunningit.Forexample:

let x 3print cf:selectcf:case [ x < 2 ] [ "x is less than 2!" ]cf:case [ x < 4 ] [ "x is less than 4!" ]cf:case [ x < 6 ] [ "x is less than 6!" ]cf:else [ "x is greater than or equal to 6!" ]

Theabovecodewillprintoutx is less than 4! sincethat’sthefirstcasewithatruecondition.

Ifnotruecaseisfound,andnocf:elsegiven,cf:selectwillerrorwithasuggestionforafix.

cf:match

cf:matchvaluelist-of-cases

cf:matchislikecf:when,exceptthatitappliestheconditionsinitscasestothegivenvalue.Forinstance:

ask patch 0 0 [ set pcolor red ]cf:match ([ pcolor ] of patch 0 0)cf:case [ [c] -> c = green ] [ print "The center patch is green!" ]cf:case [ [c] -> c = red ] [ print "The center patch is red!" ]cf:case [ [c] -> c = blue ] [ print "The center patch is blue!" ]cf:else [ print "I don't know what color the center patch is!" ]

TheabovecodewillprintoutThe center patch is green! sincethat’sthefirstcasewithatruecondition.

Thevalueisalsopassedtotheconsequentofthecase.Forinstance:

cf:match one-of turtlescf:case [ [t] -> [color] of t = red ] [ [t] -> ask t [ show "I'm red!" ] ]cf:case [ [t] -> [color] of t = blue ] [ [t] -> ask t [ show "I'm blue!" ] ]cf:else [ [t] -> ask t [ show "I'm some other color!" ] ]

Ifnomatchingcaseisfound,cf:matchwillerrorwithasuggestionforafix.

cf:matching

valuecf:matchinglist-of-cases

cf:matchingislikecf:match,exceptthatitreportstheresultofthematchingcase.cf:matchingistocf:matchascf:selectistocf:when.Forinstance:

let my-awesome-number 3print my-awesome-number cf:matchingcf:case [ [num] -> num < 2 ] [ "The number is less than 2!" ]cf:case [ [num] -> num < 4 ] [ "The number is less than 4!" ]cf:case [ [num] -> num < 6 ] [ "The number is less than 6!" ]cf:else [ "The number is greater than or equal to 6!" ]

TheabovecodewillprintoutThe number is less than 4! sincethat’sthefirstcasewithatruecondition.cf:matchingalsoappliestheconsequentofthematchingcasetothegivenvalue,justlikecf:match:

print (one-of turtles) cf:matchingcf:case [ [t] -> [color] of t = red ] [ [t] -> [ "I'm red!" ] of t ]cf:case [ [t] -> [color] of t = blue ] [ [t] -> [ "I'm blue!" ] of t ]cf:else [ [t] -> [ "I'm some other color!" ] of t ]

Ifnomatchingcaseisfound,cf:matchingwillerrorwithasuggestionforafix.

cf:case

cf:caseconditionconsequentlist-of-remaining-cases

cf:caseallowsyoutoconstructalistofcasesthattheotherprimitiveswillthenpickfrom.Itconstructsanewcasefromthethetwogiventasksandaddsittothefrontofthelistofremainingcases.Thus,youcanchainittogetherwithotherinstancesofcf:casetocreateanarbitrarilylonglistofcases.

Notethatbecausetheconditioninacaseisjustananonymousreporter,youcancheckformanycommonconditionsinaveryconcisemanner.Forinstance,ifwewanttodosomethingdependingonthebreedofaturtle,youcando:

cf:match my-turtlecf:case is-wolf? [ show "Growl!" ]cf:case is-a-sheep? [ show "Baah!" ]cf:case is-dog? [ show "Bark!" ]cf:case is-cat? [ show "Meow!" ]cf:else [ show "I'm not sure what sound to make..." ]

cf:case-is

cf:case-isrelationshipconsequentlist-of-remaining-cases

cf:case-isallowsyoutowritesomecommonusesofcf:caseincf:matchorcf:matchinginamoreconcise,readableway.Thegivenreportershouldbearelationshipsuchas=,<,ormember?.cf:case-isthenfillsinthesecondargumentofthereporterwiththegivenvalue.Thisismucheasiertounderstandinanexample:

let x 5print x cf:matchingcf:case-is = 0 [ "x is 0!" ]cf:case-is = 1 [ "x is 1!" ]cf:case-is > 2 [ "x is greater than 2!" ]cf:case-is member? [ -1 -2 -3] [ "x is either -1, -2, or -3" ]cf:else [ "x is something else" ]

Thus,cf:case-isallowsyoutodosomethingquitesimilartoswitchinsomeotherlanguages,butisalsomuchmoreflexible.

cf:else

cf:elsecommand/reporter

cf:elsecreatesacasewheretheconditionisalwaystrue.Thus,itallowsyoutocreateacasethatwillberunifalltheothercasesfail.Youshouldalmostalwaysfinishupachainofcaseswithcf:else.However,ifyou’dprefertoerrorratherthanhaveadefaultcase,youcanreplacecf:elsewith[],likeso:

let x -5cf:whencf:case [ 0 < x and x < 10 ] [ print "x is between 0 and 10!" ]cf:case [ x < 100 ] [ print "x is less than 100!" ][]

Theabovecodewillerror,sincenomatchingcasewillbefound.

NetLogoCsvExtension

Commonusecasesandexamples

Readafileallatonce

Justusecsv:from-file "/path/to/myfile.csv"!Seefrom-fileformoreinformation.

Readafileonelineatatime

Forreallybigfiles,youmaynotwanttostoretheentirefileinmemory,butratherjustprocessitalineatatime.Forinstance,ifyouwanttosumeachofthecolumnsofanumericCSVfile,youcando:

to-report sum-columns [ file ] file-open file set result csv:from-row file-read-line while [ not file-at-end? ] [ let row csv:from-row file-read-line set result (map [?1 + ?2] result row) ] file-close report resultend

Youcanalsousethistechniqueto…

Readafileonelinepertick

Here’sanexamplemodelthatreadsinafileonelinepertick:

globals [ data ]

to setup clear-all file-close-all % Close any files open from last run file-open "data.csv" % other setup goes here reset-ticksend

to go if file-at-end? [ stop ] set data csv:from-row file-read-line % model update goes here tickend

Writeafile

Justusecsv:to-file "/path/to/myfile.csv" my-data!Seeto-fileformoreinformation.

Primitives

FormattingNetLogodataasCSV

csv:to-rowcsv:to-stringcsv:to-file

ParsingCSVinputtoNetLogodata

csv:from-rowcsv:from-stringcsv:from-file

csv:from-row

csv:from-rowstringcsv:from-rowstringdelimiter

ParsesthegivenstringasthoughitwerearowfromaCSVfileandreturnsitasalistofvalues.Forexample:

observer> show csv:from-row "one,two,three"observer: ["one" "two" "three"]

Quotescanbeusedwhenitemscontaincommas:

observer> show csv:from-row "there's,a,comma,\"in,here\""observer: ["there's" "a" "comma" "in,here"]

Youcanputtwoquotesinarowtoputanactualquoteinanentry.Iftheentryisnotquoted,youcanjustuseonequote:

observer> foreach (csv:from-row "he said \"hi there\",\"afterwards, she said \"\"hello\"\"\"") printhe said "hi there"afterwards, she said "hello"

Number-like-entrieswillbeparsedasnumbers:

observer> show csv:from-row "1,-2.5,1e3"observer: [1 -2.5 1000]

trueandfalsewithanycapitalizationwillbeparsedasbooleans:

observer> show csv:from-row "true,TRUE,False,falsE"observer: [true true false false]

Touseadifferentdelimiter,youcanspecifyasecond,optionalargument.Onlysinglecharacterdelimitersaresupported:

observer> show (csv:from-row "1;2;3" ";")observer: [1 2 3]

Differenttypesofvaluescanbemixedfreely:

observer> show csv:from-row "one,2,true"observer: ["one" 2 true]

csv:from-string

csv:from-stringstringcsv:from-stringstringdelimiter

ParsesastringrepresentationofoneormoreCSVrowsandreturnsitasalistoflistsofvalues.Forexample:

observer> show csv:from-string "1,two,3\nfour,5,true"observer: [[1 "two" 3] ["four" 5 true]]

csv:from-file

csv:from-filecsv-filecsv:from-filecsv-filedelimiter

ParsesanentireCSVfiletoalistoflistsofvalues.Forexample,ifwehaveafileexample.csvthatcontains:

1,2,34,5,67,8,910,11,12

Then,weget:

observer> show csv:from-file "example.csv"observer: [[1 2 3] [4 5 6] [7 8 9] [10 11 12]]

Theparserdoesn’tcareiftherowshavedifferentnumbersofitemsonthem.Thenumberofitemsintherowslistwillalwaysbe<number of delimiters> + 1 ,thoughblanklinesareskipped.Thismakeshandlingfileswithheadersquiteeasy.Forinstance,ifwehaveheader.csvthatcontains:

My Data2/1/2015

Parameters:start,stop,resolution,population,birth?0,4,1,100,true

Data:time,x,y0,0,01,1,12,4,83,9,27

Thisgives:

observer> foreach csv:from-file "header.csv" showobserver: ["My Data"]observer: ["2/1/2015"]observer: ["Parameters:"]observer: ["start" "stop" "resolution" "population" "birth?"]observer: [0 4 1 100 true]observer: ["Data:"]observer: ["time" "x" "y"]observer: [0 0 0]observer: [1 1 1]observer: [2 4 8]observer: [3 9 27]

csv:to-row

csv:to-rowlistcsv:to-rowlistdelimiter

ReportsthegivenlistasaCSVrow.Forexample:

observer> show csv:to-row ["one" 2 true]observer: "one,2,true"

csv:to-string

csv:to-stringlistcsv:to-stringlistdelimiter

ReportsthegivenlistoflistsasaCSVstring.Forexample:

observer> show csv:to-string [[1 "two" 3] [4 5]]observer: "1,two,3\n4,5"

csv:to-file

csv:to-filecsv-filelistcsv:to-filecsv-filelistdelimiter

WritesthegivenlistofliststoanewCSVfile.Forexample:

observer> csv:to-file "myfile.csv" [[1 "two" 3] [4 5]]

willresultinafilemyfile.csvcontaining:

1,two,34,5

NetLogoGisExtension

Using

ThisextensionaddsGIS(GeographicInformationSystems)supporttoNetLogo.ItprovidestheabilitytoloadvectorGISdata(points,lines,andpolygons),andrasterGISdata(grids)intoyourmodel.

TheextensionsupportsvectordataintheformofESRIshapefiles.Theshapefile(.shp)formatisthemostcommonformatforstoringandexchangingvectorGISdata.TheextensionsupportsrasterdataintheformofESRIASCIIGridfiles.TheASCIIgridfile(.ascor.grd)isnotascommonastheshapefile,butissupportedasaninterchangeformatbymostGISplatforms.

Howtouse

Ingeneral,youfirstdefineatransformationbetweenGISdataspaceandNetLogospace,thenloaddatasetsandperformvariousoperationsonthem.TheeasiestwaytodefineatransformationbetweenGISspaceandNetLogospaceistotaketheunionofthe“envelopes”orboundingrectanglesofallofyourdatasetsinGISspaceandmapthatdirectlytotheboundsoftheNetLogoworld.SeeGISGeneralExamplesforanexampleofthistechnique.

YoumayalsooptionallydefineaprojectionfortheGISspace,inwhichcasedatasetswillbere-projectedtomatchthatprojectionastheyareloaded,aslongaseachofyourdatafileshasanassociated.prjfilethatdescribestheprojectionorgeographiccoordinatesystemofthedata.Ifnoassociated.prjfileisfound,theextensionwillassumethatthedatasetalreadyusesthecurrentprojection,regardlessofwhatthatprojectionis.

Oncethecoordinatesystemisdefined,youcanloaddatasetsusinggis:load-dataset.ThisprimitivereportseitheraVectorDatasetoraRasterDataset,dependingonwhattypeoffileyoupassit.

AVectorDatasetconsistsofacollectionofVectorFeatures,eachoneofwhichisapoint,line,orpolygon,alongwithasetofpropertyvalues.AsingleVectorDatasetmaycontainonlyoneofthethreepossibletypesoffeatures.

ThereareseveralthingsyoucandowithaVectorDataset:askitforthenamesofthepropertiesofitsfeatures,askitforits“envelope”(boundingrectangle),askforalistofallVectorFeaturesinthedataset,searchforasingleVectorFeatureorlistofVectorFeatureswhosevalueforaparticularpropertyislessthanorgreaterthanaparticularvalue,orlieswithinagivenrange,ormatchesagivenstringusingwildcardmatching(“*”,whichmatchesanynumberofoccurrencesofanycharacters).IftheVectorFeaturesarepolygons,youcanalsoapplythevaluesofaparticularpropertyofthedataset’sfeaturestoagivenpatchvariable.

TherearealsoseveralthingsyoucandowithaVectorFeaturefromaVectorDataset:askitforalistofvertexlists,askitforapropertyvaluebyname,askitforitscentroid(centerofgravity),andaskforasubsetofagivenagentsetwhoseagentsintersectthegivenVectorFeature.Forpointdata,eachvertexlistwillbeaone-elementlist.Forlinedata,eachvertexlistwillrepresenttheverticesofalinethatmakesupthatfeature.Forpolygondata,eachvertexlistwillrepresentone“ring”ofthepolygon,andthefirstandlastvertexofthelistwillbethesame.ThevertexlistsaremadeupofvaluesoftypeVertex,andthecentroidwillbeavalueoftypeVertexaswell.

ThereareanumberofoperationsdefinedforRasterDatasetsaswell.Mostlytheseinvolvesamplingthevaluesinthedataset,orre-samplingarastertoadifferentresolution.Youcanalsoapplyarastertoagivenpatchvariable,andconvolvearasterusinganarbitraryconvolutionmatrix.

CodeExample:GISGeneralExampleshasgeneralexamplesofhowtousetheextension

CodeExample:GISGradientExampleisamoreadvancedexampleofrasterdatasetanalysis.

KnownIssues

ValuesoftypeRasterDataset,VectorDataset,VectorFeature,andVertexarenothandledproperlybyexport-worldandimport-world.Tosavedatasets,youmustusethegis:store-datasetprimitive.

Thereiscurrentlynowaytodistinguishpositive-area“shell”polygonsfromnegative-area“hole”polygons,ortodeterminewhichholesareassociatedwithwhichshells.

Credits

TheprimarydeveloperoftheGISextensionwasEricRussell.

TheGISextensionmakesuseofseveralopen-sourcesoftwarelibraries.Forcopyrightandlicenseinformationonthose,seethecopyrightsectionofthemanual.TheextensionalsocontainselementsborrowedfromMyWorldGIS.

ThisdocumentationandtheexampleNetLogomodelsareinthepublicdomain.TheGISextensionitselfisfreeandopensourcesoftware.SeetheREADME.mdfileintheextension/gisdirectoryfordetails.

WewouldlovetohearyoursuggestionsonhowtoimprovetheGISextension,orjustaboutwhatyou’reusingitfor.PostquestionsandcommentsattheNetLogoUsersGroup,orwritedirectlytoEricRussellandtheNetLogoteamatccl-gis@ccl.northwestern.edu

Primitives

RasterDatasetPrimitives

gis:width-ofgis:height-ofgis:raster-valuegis:set-raster-valuegis:minimum-ofgis:maximum-ofgis:sampling-method-ofgis:set-sampling-methodgis:raster-samplegis:raster-world-envelopegis:create-rastergis:resamplegis:convolvegis:apply-raster

DatasetPrimitives

gis:load-datasetgis:store-datasetgis:type-ofgis:patch-datasetgis:turtle-datasetgis:link-dataset

VectorDatasetPrimitives

gis:shape-type-ofgis:property-namesgis:feature-list-ofgis:vertex-lists-of

http://www.myworldgis.org



gis:centroid-ofgis:location-ofgis:property-valuegis:find-featuresgis:find-one-featuregis:find-less-thangis:find-greater-thangis:find-rangegis:property-minimumgis:property-maximumgis:apply-coveragegis:coverage-minimum-thresholdgis:set-coverage-minimum-thresholdgis:coverage-maximum-thresholdgis:set-coverage-maximum-thresholdgis:intersects?gis:contains?gis:contained-by?gis:have-relationship?gis:relationship-ofgis:intersecting

CoordinateSystemPrimitives

gis:set-transformationgis:set-transformation-dsgis:set-world-envelopegis:set-world-envelope-dsgis:world-envelopegis:envelope-ofgis:envelope-union-ofgis:load-coordinate-systemgis:set-coordinate-system

DrawingPrimitives

gis:drawing-colorgis:set-drawing-colorgis:drawgis:fillgis:paintgis:import-wms-drawing

gis:set-transformation

gis:set-transformationgis-envelopenetlogo-envelope

DefinesamappingbetweenGIScoordinatesandNetLogocoordinates.Thegis-envelopeandnetlogo-envelopeparametersmusteachbefour-elementlistsconsistingof:

[minimum-x maximum-x minimum-y maximum-y]

Thescaleofthetransformationwillbeequaltotheminimumofthescalenecessarytomakethemappingbetweentherangesofxvaluesandthescalenecessarytomakethemappingbetweentherangesofyvalues.TheGISspacewillbecenteredinNetLogospace.

Forexample,thefollowingtwolistswouldmapallofgeographic(latitudeandlongitude)spaceindegreestoNetLogoworldspace,regardlessofthecurrentdimensionsoftheNetLogoworld:

(list -180 180 -90 90)(list min-pxcor max-pxcor min-pycor max-pycor)

However,ifyou’resettingtheenvelopeoftheNetLogoworld,youshouldprobablybeusingset-world-envelope.

gis:set-transformation-ds

gis:set-transformation-dsgis-envelopenetlogo-envelope

Doesthesamethingasset-transformationabove,exceptthatitallowsthescaleformappingtherangeofxvaluestobedifferentthanthescaleforyvalues.The“-ds”ontheendstandsfor“differentscales”.UsingdifferentscaleswillcausedistortionoftheshapeofGISfeatures,andsoitisgenerallynotrecommended,butitmaybeusefulforsomemodels.

Hereisanexampleofthedifferencebetweenset-transformationandset-transformation-ds:

Using[set-transformation](#gisset-transformation),the

scalealongthexandyaxisisthesame,preservingtheround

shapeoftheEarthinthisOrthographicprojection.

Using[set-transformation-ds](#gisset-transformation-ds),thescalealongthexaxisisstretchedsothatthe

earthcoverstheentireNetLogoView,whichinthiscasedistortstheshape

oftheEarth.

gis:set-world-envelope

gis:set-world-envelopegis-envelope

AshorthandforsettingthetransformationbymappingtheenvelopeoftheNetLogoworldtothegivenenvelopeinGISspace,whilekeepingthescalesalongthexandyaxisthesame.Itisequivalentto:

set-transformation gis-envelope (list min-pxcor max-pxcor min-pycor max-pycor)

Thisprimitiveissuppliedbecausemostofthetimeyou’llwanttosettheenvelopeoftheentireNetLogoworld,ratherthanjustapartofit.

gis:set-world-envelope-ds

gis:set-world-envelope-dsgis-envelope

AshorthandforsettingthetransformationbymappingtheenvelopeoftheNetLogoworldtothegivenenvelopeinGISspace,usingdifferentscalesalongthexandyaxisifnecessary.Itisequivalentto:

set-transformation-ds gis-envelope (list min-pxcor max-pxcor min-pycor max-pycor)

Seethepicturesaboveforthedifferencebetweenusingequalscalesforxandycoordinatesandusingdifferentscales.

gis:world-envelope

gis:world-envelope

Reportstheenvelope(boundingrectangle)oftheNetLogoworld,transformedintoGISspace.Anenvelopeconsistsofafour-elementlistoftheform:


gis:envelope-of

gis:envelope-ofthing

Reportstheenvelope(boundingrectangle)ofthinginGIScoordinates.ThethingmaybeanAgent,anAgentSet,aRasterDataset,aVectorDataset,oraVectorFeature.Anenvelopeconsistsofafour-elementlistoftheform:


gis:envelope-union-of

gis:envelope-union-ofenvelope1envelope2gis:envelope-union-ofenvelope1...

Reportsanenvelope(boundingrectangle)thatentirelycontainsthegivenenvelopes.Anenvelopeconsistsofafour-elementlistoftheform


Noassumptionismadeaboutthecoordinatesystemofthearguments,thoughiftheyarenotinthesamecoordinatesystem,resultswillbeunpredictable.

gis:load-coordinate-system

gis:load-coordinate-systemfile

Loadsanewglobalprojectionusedforprojectingorre-projectingGISdataasitisloadedfromafile.ThefilemustcontainavalidWell-KnownText(WKT)projectiondescription.

WKTprojectionfilesarefrequentlydistributedalongsideGISdatafiles,andusuallyhavea“.prj”filenameextension.

Relativepathsareresolvedrelativetothelocationofthecurrentmodel,ortheuser’shomedirectoryifthecurrentmodelhasn’tbeensavedyet.

TheGISextensiondoesnotsupportallWKTcoordinatesystemsandprojections.Onlygeographic("GEOGCS")andprojected("PROJCS")coordinatesystemsaresupported.Forprojectedcoordinatesystems,onlythefollowingprojectionsaresupported:

Albers_Conic_Equal_AreaLambert_Conformal_Conic_2SPPolyconicLambert_Azimuthal_Equal_AreaMercator_1SPRobinsonAzimuthal_EquidistantMillerStereographic

http://geoapi.sourceforge.net/2.0/javadoc/org/opengis/referencing/doc-files/WKT.html

Cylindrical_Equal_AreaOblique_MercatorTransverse_MercatorEquidistant_Conichotine_oblique_mercatorGnomonicOrthographic

Seeremotesensing.orgforacompletelistofWKTprojectionsandtheirparameters.

gis:set-coordinate-system

gis:set-coordinate-systemsystem

Setstheglobalprojectionusedforprojectingorre-projectingGISdataasitisloaded.ThesystemmustbeeitherastringinWell-KnownText(WKT)format,oraNetLogolistthatconsistsofWKTconvertedtoalistbymovingeachkeywordinsideitsassociatedbracketsandputtingquotesaroundit.Thelatterispreferredbecauseitmakesthecodemuchmorereadable.

ThesamelimitationsonWKTsupportapplyasdescribedaboveinthedocumentationforload-coordinate-system

gis:load-dataset

gis:load-datasetfile

Loadsthegivendatafile,re-projectingthedataasnecessaryifaglobalprojectionisdefinedandifthedatafileitselfhasanassociated.prjfile,thenreportstheresultingdataset.

Ifno“.prj”fileispresent,thenload-datasetassumesthattheprojectionofthedatabeingloadedisthesameasthecurrentglobalcoordinatesystem.

Relativepathsareresolvedrelativetothelocationofthecurrentmodel,ortheuser’shomedirectoryifthecurrentmodelhasn’tbeensavedyet.

Currently,twotypesofdatafilearesupported:

“.shp”(ESRIshapefile):containsvectordata,consistingofpoints,lines,orpolygons.Whenthetargetfileisashapefile,load-datasetreportsaVectorDataset.“.asc”or“.grd”(ESRIASCIIgrid):containsrasterdata,consistingofagridofvalues.WhenthetargetfileisanASCIIgridfile,load-datasetreportsaRasterDataset.

gis:store-dataset

gis:store-datasetdatasetfile

Savesthegivendatasettothegivenfile.Ifthenameofthefiledoesnothavetheproperfileextension,theextensionwillbeautomaticallyappendedtothename.Relativepathsareresolvedrelativetothelocationofthecurrentmodel,ortheuser’shomedirectoryifthecurrentmodelhasn’tbeensavedyet.

Currently,thisprimitiveonlyworksforRasterDatasets,anditcanonlysavethosedatasets

http://remotesensing.org/geotiff/proj_list/

http://geoapi.sourceforge.net/2.0/javadoc/org/opengis/referencing/doc-files/WKT.html

asESRIASCIIgridfiles.

gis:type-of

gis:type-ofdataset

ReportsthetypeofthegivenGISdataset:either“VECTOR”or“RASTER”

gis:patch-dataset

gis:patch-datasetpatch-variable

ReportsanewrasterwhosecellscorresponddirectlytoNetLogopatches,andwhosecellvaluesconsistofthevaluesofthegivenpatchvariable.Thisprimitiveisbasicallytheinverseofapply-raster;apply-rastercopiesvaluesfromarasterdatasettoapatchvariable,whilethisprimitivecopiesvaluesfromapatchvariabletoarasterdataset.

gis:turtle-dataset

gis:turtle-datasetturtle-set

Reportsanew,pointVectorDatasetbuiltfromtheturtlesinthegivenagentset.Thepointsarelocatedatlocationsoftheturtles,translatedfromNetLogospaceintoGISspaceusingthecurrentcoordinatetransformation.Andthedataset’spropertiesconsistofalloftheturtlevariablescommontoeveryturtleintheagentset.

gis:link-dataset

gis:link-datasetlink-set

Reportsanew,lineVectorDatasetbuiltfromthelinksinthegivenagentset.Theendpointsofeachlineareatthelocationoftheturtlesconnectedbyeachlink,translatedfromNetLogospaceintoGISspaceusingthecurrentcoordinatetransformation.Andthedataset’spropertiesconsistofallofthelinkvariablescommontoeverylinkintheagentset.

gis:shape-type-of

gis:shape-type-ofVectorDataset

Reportstheshapetypeofthegivendataset.Thepossibleoutputvaluesare“POINT”,“LINE”,and“POLYGON”.

gis:property-names

gis:property-namesVectorDataset

ReportsalistofstringswhereeachstringisthenameofapropertypossessedbyeachVectorFeatureinthegivenVectorDataset,suitableforuseingis:property-value.

gis:feature-list-of

gis:feature-list-ofVectorDataset

ReportsalistofallVectorFeaturesinthegivendataset.

gis:vertex-lists-of

gis:vertex-lists-ofVectorFeature

ReportsalistoflistsofVertexvalues.Forpointdatasets,eachvertexlistwillcontainexactlyonevertex:thelocationofapoint.Forlinedatasets,eachvertexlistwillcontainatleasttwopoints,andwillrepresenta“polyline”,connectingeachadjacentpairofverticesinthelist.Forpolygondatasets,eachvertexlistwillcontainatleastthreepoints,representingapolygonconnectingeachvertex,andthefirstandlastverticesinthelistwillbethesame.

gis:centroid-of

gis:centroid-ofVectorFeature

ReportsasingleVertexrepresentingthecentroid(centerofgravity)ofthegivenfeature.Forpointdatasets,thecentroidisdefinedastheaveragelocationofallpointsinthefeature.Forlinedatasets,thecentroidisdefinedastheaverageofthelocationsofthemidpointsofalllinesegmentsinthefeature,weightedbysegmentlength.Forpolygondatasets,thecentroidisdefinedastheweightedsumofthecentroidsofadecompositionoftheareainto(possiblyoverlapping)triangles.SeethisFAQformoredetailsonthepolygoncentroidalgorithm.

gis:location-of

gis:location-ofVertex

Reportsatwo-elementlistcontainingthexandyvalues(inthatorder)ofthegivenvertextranslatedintoNetLogoworldspaceusingthecurrenttransformation,oranemptylistifthegivenvertexliesoutsidetheNetLogoworld.

gis:property-value

gis:property-valueVectorFeatureproperty-name

ReportsthevalueofthepropertywiththegivennameforthegivenVectorDataset.Thereportedvaluemaybeanumber,astring,orabooleanvalue,dependingonthetypeofthefieldintheunderlyingdatafile.

Forshapefiles,valuesfromdBaseCHARACTERandDATEfieldsarereturnedasstrings,valuesfromNUMBERandFLOATfieldsarereturnedasnumbers,andvaluesfromLOGICALfieldsarereturnedasbooleanvalues.MEMOfieldsarenotsupported.DATEvaluesareconvertedtostringsusingISO8601format(YYYY-MM-DD).

gis:find-features

http://www.faqs.org/faqs/graphics/algorithms-faq/

gis:find-featuresVectorDatasetproperty-namespecified-value

ReportsalistofallVectorFeaturesinthegivendatasetwhosevalueforthepropertyproperty-namematchesspecified-value(astring).Valuecomparisonisnotcasesensitive,andthewildcardcharacter“*”willmatchanynumberofoccurrences(includingzero)ofanycharacter.

gis:find-one-feature

gis:find-one-featureVectorDatasetproperty-namespecified-value

ReportsthefirstVectorFeatureinthedatasetwhosevalueforthepropertyproperty-namematchesthegivenstring.Valuecomparisonisnotcasesensitive,andthewildcardcharacter“*”willmatchanynumberofoccurrences(includingzero)ofanycharacter.Featuresaresearchedintheorderthattheyappearinthedatafilethatwasthesourceofthedataset,andsearchingstopsassoonasamatchisfound.ReportsnobodyifnomatchingVectorFeatureisfound.

gis:find-less-than

gis:find-less-thanVectorDatasetproperty-namevalue

ReportsalistofallVectorFeaturesinthegivendatasetwhosevalueforthepropertyproperty-nameislessthanthegivenvalue.Stringvaluesarecomparedusingcase-sensitivelexicographicorderasdefinedintheJavaDocumentation.Usingastringvalueforanumericpropertyoranumericvalueforastringpropertywillcauseanerror.

gis:find-greater-than

gis:find-greater-thanVectorDatasetproperty-namevalue

ReportsalistofallVectorFeaturesinthegivendatasetwhosevalueforthepropertyproperty-nameisgreaterthanthegivenvalue.Stringvaluesarecomparedusingcase-sensitivelexicographicorderasdefinedintheJavaDocumentation.Usingastringvalueforanumericpropertyoranumericvalueforastringpropertywillcauseanerror.

gis:find-range

gis:find-rangeVectorDatasetproperty-nameminimum-valuemaximum-value

ReportsalistofallVectorFeaturesinthegivendatasetwhosevalueforthepropertyproperty-nameisstrictlygreaterthanminimum-valueandstrictlylessthanmaximum-value.Stringvaluesarecomparedusingcase-sensitivelexicographicorderasdefinedintheJavaDocumentation.Usingastringvalueforanumericpropertyoranumericvalueforastringpropertywillcauseanerror.

gis:property-minimum

gis:property-minimumVectorDatasetproperty-name

ReportsthesmallestvalueforthegivenpropertyoveralloftheVectorFeaturesinthe

http://docs.oracle.com/javase/1.5.0/docs/api/java/lang/String.html#compareTo(java.lang.String)



givendataset.Stringvaluesarecomparedusingcase-sensitivelexicographicorderasdefinedintheJavaDocumentation.

gis:property-maximum

gis:property-maximumVectorDatasetproperty-name

ReportsthelargestvalueforthegivenpropertyoveralloftheVectorFeaturesinthegivendataset.Stringvaluesarecomparedusingcase-sensitivelexicographicorderasdefinedintheJavaDocumentation.

gis:apply-coverage

gis:apply-coverageVectorDatasetproperty-namepatch-variable

CopiesvaluesfromthegivenpropertyoftheVectorDataset’sfeaturestothegivenpatchvariable.Thedatasetmustbeapolygondataset;pointsandlinesarenotsupported.

Foreachpatch,itfindsallVectorFeaturesthatintersectthatpatch.Then,ifthepropertyisastringproperty,itcomputesthemajorityvaluebycomputingthetotalareaofthepatchcoveredbyVectorFeatureshavingeachpossiblevalueoftheproperty,thenreturningthevaluewhichrepresentsthelargestproportionofthepatcharea.Ifthepropertyisanumericproperty,itcomputesaweightedaverageofpropertyvaluesfromallVectorFeatureswhichintersectthepatch,weightedbytheproportionofthepatchareatheycover.

Therearetwoexceptionstothisdefaultbehavior:

Ifapercentageofapatches’areagreaterthanthecoverage-maximum-thresholdiscoveredbyasingleVectorFeature,thenthepropertyvaluefromthatVectorFeatureiscopieddirectly.IfmorethanoneVectorFeaturecoversapercentageofareagreaterthanthethreshold,onlythefirstwillbeused.

Ifthetotalpercentageofapatches’areacoveredbyVectorFeaturesislessthanthecoverage-minimum-threshold,thetargetpatchvariableissettoNotANumber.

Bydefault,theminimumthresholdis10%andthemaximumthresholdis33%.Thesevaluesmaybemodifiedusingthefourprimitivesthatfollow.

gis:coverage-minimum-threshold

gis:coverage-minimum-threshold

Reportsthecurrentcoverageminimumthresholdusedbygis:apply-coverage.

gis:set-coverage-minimum-threshold

gis:set-coverage-minimum-thresholdnew-threshold

Setsthecurrentcoverageminimumthresholdtobeusedbygis:apply-coverage.

gis:coverage-maximum-threshold



gis:coverage-maximum-threshold

Reportsthecurrentcoveragemaximumthresholdusedbygis:apply-coverage.

gis:set-coverage-maximum-threshold

gis:set-coverage-maximum-thresholdnew-threshold

Setsthecurrentcoveragemaximumthresholdtobeusedbygis:apply-coverage.

gis:intersects?

gis:intersects?xy

Reportstrueifthegivenobjects’spatialrepresentationsshareatleastonepointincommon,andfalseotherwise.Theobjectsxandymaybeanyoneof:

aVectorDataset,inwhichcasetheobject’sspatialrepresentationistheunionofallthepoints,lines,orpolygonsthedatasetcontains.aVectorFeature,inwhichcasetheobject’sspatialrepresentationisdefinedbythepoint,line,orpolygonthefeaturecontains.Aturtle,inwhichcasethespatialrepresentationisapoint.Alink,whosespatialrepresentationisalinesegmentconnectingthetwopointsrepresentedbytheturtlesthelinkisconnecting.Apatch,whosespatialrepresentationisarectangularpolygon.Anagentset,whosespatialrepresentationistheunionoftherepresentationsofalloftheagentsitcontains.Alistcontainingofanyoftheitemslistedhere,includinganotherlist.Thespatialrepresentationofsuchalististheunionofthespatialrepresentationsofitscontents.

gis:contains?

gis:contains?xy

Reportstrueifeverypointofy’sspatialrepresentationisalsoapartofx’sspatialrepresentation.Notethatthismeansthatpolygonsdocontaintheirboundaries.Theobjectsxandymaybeanyoneof


gis:contained-by?

gis:contained-by?xy

Reportstrueifeverypointofx’sspatialrepresentationisalsoapartofy’sspatialrepresentation.Theobjectsxandymaybeanyoneof:


gis:have-relationship?

gis:have-relationship?xy

Reportstrueifthespatialrepresentationsofthetwoobjectshavethegivenspatialrelationship,andfalseotherwise.ThespatialrelationshipisspecifiedusingaDimensionallyExtendedNine-IntersectionModel(DE-9IM)matrix.Thematrixconsistsof9elements,eachofwhichspecifiestherequiredrelationshipbetweenthetwoobjects’interiorspace,boundaryspace,orexteriorspace.Theelementsmusthaveoneofsixpossiblevalues:

“T”,meaningthespacesmustintersectinsomeway“F”,meaningthespacesmustnotintersectinanyway“0”,meaningthedimensionofthespaces’intersectionmustbezero(i.e.,itmustbeapointornon-emptysetofpoints).“1”,meaningthedimensionofthespaces’intersectionmustbeone(i.e.,itmustbealineornon-emptysetoflinesegments).“2”,meaningthedimensionofthespaces’intersectionmustbetwo(i.e.,itmustbeapolygonorsetofpolygonswhoseareaisgreaterthanzero).“*”,meaningthatthetwospacesmayhaveanyrelationship.

Forexample,thismatrix:

xInterior Boundary Exterior

yInterior T * *

Boundary * * *Exterior F F *

wouldreturntrueifandonlyifsomepartofobjectx’sinteriorliesinsideobjecty’sinterior,andnopartofobjectx’sinteriororboundaryintersectsobjecty’sexterior.Thisisessentiallyamorerestrictiveformofthecontains?primitive;oneinwhichpolygonsarenotconsideredtocontaintheirboundaries.

Thematrixisgiventothehave-relationship?primitiveasastring,whoseelementsaregiveninthefollowingorder:

1 2 34 5 67 8 9

Sotousetheexamplematrixabove,youwouldwrite:

gis:have-relationship? x y "T*****FF*"

AmuchmoredetailedandformaldescriptionoftheDE-9IMmatrixandtheassociatedpoint-settheorycanbefoundintheOpenGISSimpleFeaturesSpecificationforSQL.

Theobjectsxandymaybeanyoneof:


gis:relationship-of

gis:relationship-ofxy

ReportstheDimensionallyExtendedNine-IntersectionModel(DE-9IM)matrixthatdescribesthespatialrelationshipofthetwoobjects.Thematrixconsistsof9elements,eachofwhichdescribestherelationshipbetweenthetwoobjects’interiorspace,boundaryspace,orexteriorspace.Eachelementwilldescribethedimensionoftheintersectionoftwospaces,meaningthatitmayhaveoneoffourpossiblevalues:

“-1”,meaningthespacesdonotintersect“0”,meaningthedimensionofthespaces’intersectioniszero(i.e.,theyintersectatapointorsetofpoints).“1”,meaningthedimensionofthespaces’intersectionisone(i.e.,theyintersectalongoneormorelines).“2”,meaningthedimensionofthespaces’intersectionistwo(i.e.,theirintersectionisanon-emptypolygon).

Forexample,thetwopolygonsxandyshownhere:

http://www.opengeospatial.org/standards/sfs

havethefollowingDE-9IMmatrix:

xInterior Boundary Exterior

yInterior 2 1 2

Boundary 1 0 1Exterior 2 1 2

Whichwouldbereportedbytherelationship-ofprimitiveasthestring“212101212”.

AmuchmoredetailedandformaldescriptionoftheDE-9IMmatrixandtheassociatedpoint-settheorycanbefoundintheOpenGISSimpleFeaturesSpecificationforSQL.

Theobjectsxandymaybeanyoneof:


gis:intersecting

patch-setgis:intersectingdata

ReportsanewagentsetcontainingonlythosemembersofthegivenagentsetwhichintersectgivenGISdata,whichmaybeanyoneof:aVectorDataset,aVectorFeature,anAgent,anAgentSet,oralistcontaininganyoftheabove.

gis:width-of

gis:width-ofRasterDataset

Reportsthenumberofcolumnsinthedataset.Notethatthisisthenumberofcellsfromlefttoright,notthewidthofthedatasetinGISspace.

http://www.opengeospatial.org/standards/sfs

gis:height-of

gis:height-ofRasterDataset

Reportsthenumberofrowsinthedataset.Notethatthisisthenumberofcellsfromtoptobottom,nottheheightofthedatasetinGISspace.

gis:raster-value

gis:raster-valueRasterDatasetxy

Reportsthevalueofthegivenrasterdatasetinthegivencell.Cellcoordinatesarenumberedfromlefttoright,andfromtoptobottom,beginningwithzero.Sotheupperleftcellis(0,0),andthebottomrightcellis(gis:width-of dataset-1,gis:height-of dataset-1).

gis:set-raster-value

gis:set-raster-valueRasterDatasetxyvalue

Setsthevalueofthegivenrasterdatasetatthegivencelltoanewvalue.Cellcoordinatesarenumberedfromlefttoright,andfromtoptobottom,beginningwithzero.Sotheupperleftcellis(0,0),andthebottomrightcellis(gis:width-of dataset-1,gis:height-ofdataset-1).

gis:minimum-of

gis:minimum-ofRasterDataset

Reportsthehighestvalueinthegivenrasterdataset.

gis:maximum-of

gis:maximum-ofRasterDataset

Reportsthelowestvalueinthegivenrasterdataset.

gis:sampling-method-of

gis:sampling-method-ofRasterDataset

Reportsthesamplingmethodusedtocomputethevalueofthegivenrasterdatasetatasinglepoint,oroveranareasmallerthanasinglerastercell.SamplingisperformedbytheGISextensionprimitivesraster-sample,resample,convolve,andapply-raster.Thesamplingmethodwillbeoneofthefollowing:

"NEAREST_NEIGHBOR":thevalueofthecellnearestthesamplinglocationisused."BILINEAR":thevalueofthefournearestcellsaresampledbylinearweighting,accordingtotheirproximitytothesamplingsite."BICUBIC":thevalueofthesixteennearestcellsaresampled,andtheirvaluesare

combinedbyweightaccordingtoapiecewisecubicpolynomialrecommendedbyRifman(seeDigitalImageWarping,GeorgeWolberg,1990,pp129-131,IEEEComputerSocietyPress)."BICUBIC_2":thevalueissampledusingthesameprocedureandthesamepolynomialaswithBICUBICabove,butusingadifferentcoefficient.ThismethodmayproducesomewhatsharperresultsthanBICUBIC,butthatresultisdatadependent.

Formoreinformationonthesesamplingmethodsandonrastersamplingingeneral,seethiswikipediaarticle.

gis:set-sampling-method

gis:set-sampling-methodRasterDatasetsampling-method

Setsthesamplingmethodusedbythegivenrasterdatasetatasinglepoint,oroveranareasmallerthanasinglerastercell.SamplingisperformedbytheGISextensionprimitivesraster-sample,resample,convolve,andapply-raster.Thesamplingmethodmustbeoneofthefollowing:

"NEAREST_NEIGHBOR""BILINEAR""BICUBIC""BICUBIC_2"

Seesampling-method-ofaboveforamorespecificdescriptionofeachsamplingmethod.

gis:raster-sample

gis:raster-sampleRasterDatasetsample-location

Reportsthevalueofthegivenrasteroverthegivenlocation.Thelocationmaybeanyofthefollowing:

Alistoflength2,whichistakentorepresentapointinnetlogospace([xcor ycor])ofthesortreportedbylocation-ofVertex.Therasterdatasetissampledatthepointofthatlocation.Alistoflength4,whichistakentorepresentanenvelopeinGISspace,ofthesortreportedbyenvelope-of.Therasterdatasetissampledovertheareaofthatenvelope.Apatch,inwhichcasetherasterdatasetissampledovertheareaofthepatch.Aturtle,inwhichcasetherasterdatasetissampledatthelocationofthatturtle.AVertex,inwhichcasetherasterdatasetissampledatthelocationofthatVertex.

Iftherequestedlocationisoutsidetheareacoveredbytherasterdataset,thisprimitivereportsthespecialvaluerepresenting“notanumber”,whichisprintedbyNetLogoas“NaN”.Usingthespecial“notanumber”valueasanargumenttoprimitivesthatexpectanumbermaycauseanerror,butyoucantestthevaluereportedbythisprimitivetofilterout“notanumber”values.Avaluethatisnotanumberwillbeneitherlessthannorgreaterthananumbervalue,soyoucandetect“notanumber”valuesusingthefollowing:

let value gis:raster-sample dataset turtle 0; set color to blue if value is a number, red if value is "not a number"ifelse (value <= 0) or (value >= 0)[ set color blue ][ set color red ]

http://en.wikipedia.org/wiki/Image_scaling

Iftherequestedlocationisapoint,thesampleisalwayscomputedusingthemethodsetbyset-sampling-method.Iftherequestedlocationisanarea(i.e.,anenvelopeorpatch),thesampleiscomputedbytakingtheaverageofallrastercellscoveredbytherequestedarea.

gis:raster-world-envelope

gis:raster-world-envelopeRasterDatasetxy

ReportstheGISenvelopeneededtomatchtheboundariesofNetLogopatcheswiththeboundariesofcellsinthegivenrasterdataset.Thisenvelopecouldthenbeusedasanargumenttoset-transformation-ds.

TheremaybemorecellsinthedatasetthantherearepatchesintheNetLogoworld.Inthatcase,youwillneedtoselectasubsetofcellsinthedatasetbyspecifyingwhichcellinthedatasetyouwanttomatchwiththeupper-leftcorneroftheNetLogoworld.Cellsarenumberedfromlefttoright,andfromtoptobottom,beginningwithzero.Sotheupperleftcellis(0,0),andthebottomrightcellis(gis:width-of dataset-1,gis:height-of dataset-1).

gis:create-raster

gis:create-rasterwidthheightenvelope

Createsandreportsanew,emptyrasterdatasetwiththegivennumberofcolumnsandrows,coveringthegivenenvelope.

gis:resample

gis:resampleRasterDatasetenvelopewidthheight

ReportsanewdatasetthatconsistsofthegivenRasterDatasetresampledtocoverthegivenenvelopeandtocontainthegivennumberofcolumnsandrows.Ifthenewraster’scellsaresmallerthantheexistingraster’scells,theywillberesampledusingthemethodsetbyset-sampling-method.Ifthenewcellsarelargerthantheoriginalcells,theywillbesampledusingthe"NEAREST_NEIGHBOR"method.

gis:convolve

gis:convolveRasterDatasetkernel-rowskernel-columnskernelkey-columnkey-row

Reportsanewrasterwhosedataconsistsofthegivenrasterconvolvedwiththegivenkernel.

Aconvolutionisamathematicaloperationthatcomputeseachoutputcellbymultiplyingelementsofakernelwiththecellvaluessurroundingaparticularsourcecell.Akernelisamatrixofvalues,withoneparticularvaluedefinedasthe“keyelement”,thevaluethatiscenteredoverthesourcecellcorrespondingtothedestinationcellwhosevalueisbeingcomputed.

Thevaluesofthekernelmatrixaregivenasalist,whichenumeratestheelementsofthematrixfromlefttoright,toptobottom.Sotheelementsofa3-by-3matrixwouldbelisted

inthefollowingorder:

1 2 34 5 67 8 9

Thekeyelementisspecifiedbycolumnandrowwithinthematrix.Columnsarenumberedfromlefttoright,beginningwithzero.Rowsarenumberedfromtoptobottom,alsobeginningwithzero.So,forexample,thekernelforthehorizontalSobeloperator,whichlookslikethis:

1 0 -1

2 0(key)

-2

1 0 -1

wouldbespecifiedasfollows:

let horizontal-gradient gis:convolve dataset 3 3 [1 0 -1 2 0 -2 1 0 -1] 1 1

gis:apply-raster

gis:apply-rasterRasterDatasetpatch-variable

Copiesvaluesfromthegivenrasterdatasettothegivenpatchvariable,resamplingtherasterasnecessarysothatitscellboundariesmatchupwithNetLogopatchboundaries.Thisresamplingisdoneasifusingresampleratherthanraster-sample,forthesakeofefficiency.However,patchesnotcoveredbytherasterareassignedvaluesof“notanumber”inthesamewaythatraster-samplereportsvaluesforlocationsoutsidetheraster.

gis:drawing-color

gis:drawing-color

ReportsthecolorusedbytheGISextensiontodrawvectorfeaturesintotheNetLogodrawinglayer.ColorcanberepresentedeitherasaNetLogocolor(asinglenumberbetweenzeroand140)oranRGBcolor(alistof3numbers).SeedetailsintheColorssectionoftheProgrammingGuide.

gis:set-drawing-color

gis:set-drawing-colorcolor

SetsthecolorusedbytheGISextensiontodrawvectorfeaturesintotheNetLogodrawinglayer.ColorcanberepresentedeitherasaNetLogocolor(asinglenumberbetweenzeroand140)oranRGBcolor(alistof3numbers).SeedetailsintheColorssectionoftheProgrammingGuide.

gis:draw

http://en.wikipedia.org/wiki/Sobel_operator

gis:drawvector-dataline-thickness

DrawsthegivenvectordatatotheNetLogodrawinglayer,usingthecurrentGISdrawingcolor,withthegivenlinethickness.ThedatamayconsisteitherofanentireVectorDataset,orasingleVectorFeature.Thisprimitivedrawsonlytheboundaryofpolygondata,andforpointdata,itfillsacirclewitharadiusequaltothelinethickness.

gis:fill

gis:fillvector-dataline-thickness

FillsthegivenvectordataintheNetLogodrawinglayerusingthecurrentGISdrawingcolor,usingthegivenlinethicknessaroundtheedges.ThedatamayconsisteitherofanentireVectorDataset,orasingleVectorFeature.Forpointdata,itfillsacirclewitharadiusequaltothelinethickness.

gis:paint

gis:paintRasterDatasettransparency

PaintsthegivenrasterdatatotheNetLogodrawinglayer.Thehighestvalueinthedatasetispaintedwhite,thelowestispaintedinblack,andtheothervaluesarepaintedinshadesofgrayscaledlinearlybetweenwhiteandblack.

Thetransparencyinputdetermineshowtransparentthenewimageinthedrawingwillbe.Validinputsrangefrom0(completelyopaque)to255(completelytransparent).

gis:import-wms-drawing

gis:import-wms-drawingserver-urlspatial-referencelayerstransparency

ImportsanimageintotheNetLogodrawinglayerusingtheWebMappingServiceprotocol,asdefinedbytheOpenGeospatialConsortium.

Thespatialreferenceandlayersinputsshouldbegivenasstrings.ThespatialreferenceinputcorrespondstotheSRSparametertotheGetMaprequestasdefinedinsection7.2.3.5ofversion1.1.1oftheWMSstandard.ThelayersinputcorrespondstotheLAYERSparametertotheasdefinedin7.2.3.3ofversion1.1.1oftheWMSstandard.

YoucanfindthelistofvalidspatialreferencecodesandlayernamesbyexaminingtheresponsetoaGetCapabilitiesrequesttotheWMSserver.ConsulttherelevantstandardforinstructionsonhowtoissueaGetCapabilitiesrequesttotheserverandhowtointerprettheresults.

Thetransparencyinputdetermineshowtransparentthenewimageinthedrawingwillbe.Validinputsrangefrom0(completelyopaque)to255(completelytransparent).

http://www.opengeospatial.org/standards/wms

http://www.opengeospatial.org/

NetLogoGogoExtension

Usage

TheGoGoExtensioncomespreinstalledwhenyoudownloadandinstallNetLogo.Tousetheextensioninyourmodel,addthislinetothetopofyourCodetab:

extensions [ gogo ]

Ifyourmodelalreadyusesotherextensions,thenitalreadyhasanextensionslineinit,sojustaddgogotothelist.

Afterloadingtheextension,youcanseewhetheroneormoreHID-basedgogosareonandattachedtothecomputerbytypingthefollowingintothecommandcenter:

gogo:howmany-gogos

Changes

ComparedtopreviousversionsoftheGoGoextension,thisversionoffers:

Improvedrobustness.WithpriorversionsoftheGoGoextension,crasheswerefairlycommonduetoproblemsintheUSB-Serialstackacrossplatforms.TheswitchtoHIDimprovedrobustness,andthenewextensionalsousesa“daemon”architecturewhichshieldsNetLogofromanyproblemsthatmayoccurindirectcommunicationwiththeGoGoboard.TheresultisasubstantialreductioninthenumberofcrashesofNetLogo.NoInstallationofDrivers.BecausethenewGoGofirmwarepresentstheboardasanHIDdevice,theextensioncouldbewrittensoasnottorequireinstallingdrivers.Thismeansthereisnoneedfortheusertohaveadministratorrightsonthecomputer.DirectionalityforMotors.Theboardnowhaspolarity-ensuringoutputconnectors,sothat“counterclockwise”or“clockwise”cannowbespecifiedincode.

Primitives

OtherOutputs

gogo:ledgogo:beep

Utilities

gogo:read-all

General

gogo:primitivesgogo:howmany-gogos

Sensors

gogo:read-sensorsgogo:read-sensor

OutputsandServos

gogo:talk-to-output-portsgogo:set-output-port-powergogo:output-port-ongogo:output-port-offgogo:output-port-clockwisegogo:output-port-counterclockwisegogo:set-servo

gogo:primitives

gogo:primitives

Returnsalistoftheprimitivesofthisextension.

gogo:howmany-gogos

gogo:howmany-gogos

ReportsthenumberofUSBHIDdevicesvisibletothecomputerandhavingthecorrectvendorandproductIDtobeaGoGoboard.Aboardwillonlybedetectedifitisbothconnectedandpoweredon.UsingthisprimitiveisonewaytodeterminequicklywhetheraGoGoboardhastheHIDfirmwareloaded.(AUSB-Serialversionoftheboardwillnotbedetected.).

gogo:talk-to-output-ports

gogo:talk-to-output-portslist-of-portnames

Establishesalistofoutputportsthatwillbecontrolledwithsubsequentoutput-portcommands.Seebelow…

gogo:set-output-port-power

gogo:set-output-port-powerpower-level

power-levelisanumberbetween0and100,reflectingthepercentageofmaximumpower.Setstheamountofpowerthatwillbefedtotheoutputportsindicatedintalk-to-output-ports.Thiswillnotaffecttheon-offstateoftheoutputports.So,forexample,ifamotorisalreadyconnectedtoanoutputportandrunning,changingitspowerwillchangeitsspeed.Ifthemotorisnotrunning,changingthepowerlevelwillnotturniton;instead,itwillaffectthespeedatwhichthemotorstartswhenitisturnedonwithoutput-port-on.

gogo:output-port-on

gogo:output-port-on

Turnsontheoutputportswhichhavebeenindicatedwithtalk-to-output-ports.Ifnonehavebeensetwithtalk-to-output-ports,noportswillbeturnedon.

gogo:output-port-off

gogo:output-port-off

Turnsofftheoutputportswhichhavebeenindicatedwithtalk-to-output-ports.Ifnonehavebeensetwithtalk-to-output-ports,noportswillbeturnedoff.

gogo:output-port-clockwise

gogo:output-port-clockwise

Setsthepolarityoftheoutputport(s)thathavebeenspecifiedwithtalk-to-output-ports,sothatamotorattachedtooneoftheseportswouldturnclockwise.

gogo:output-port-counterclockwise

gogo:output-port-counterclockwise

Setsthepolarityoftheoutputport(s)thathavebeenspecifiedwithtalk-to-output-ports,sothatamotorattachedtooneoftheseportswouldturncounterclockwise.

gogo:set-servo

gogo:set-servonumber

SetsthePulse-WidthModulation(PWM)proportionoftheoutputport(s)thathavebeenspecifiedwithtalk-to-output-ports.Notethattheservoconnectorsarethemalepinsnexttothestandardmotorconnectors.DifferentservosrespondtodifferentPWMranges,butallservosreadPWMproportionsandsetthepositionoftheirmaingearaccordingly.

gogo:led

gogo:ledon-or-off

Turnstheuser-LEDonoroff,dependingontheargument.gogo:led1turnstheLEDon;gogo:led0turnsitoff.

gogo:beep

gogo:beep

CausestheGoGoboardtobeep.

gogo:read-sensors

gogo:read-sensors

ReportsalistcontainingthecurrentreadingsofalleightsensorsportsoftheGoGo.

gogo:read-sensor

gogo:read-sensorwhich-sensor

Reportsthevalueofsensornumberwhich-sensor,wherewhich-sensorisanumberbetween0-7.

gogo:read-all

gogo:read-all

Reportsalldataavailablefromtheboard,inaraw-listformusefulfordebugging.

gogo:send-bytes

gogo:send-byteslist

SendsalistofbytestotheGoGoboard.UsefulfordebuggingorfortestinganyneworfuturefunctionalitythatisaddedtotheGoGoboardwithnewfirmwareupdates.

NetLogoLsExtension

LevelSpacefundamentals

LevelSpacemustbeloadedinamodelusingextensions [ls]atthetopofyourmodel.Oncethisisdone,amodelwillbeabletoloadupothermodelsusingtheLevelSpaceprimitives,runcommandsandreportersinthem,andclosethemdownwhentheyarenolongerneeded.

AskingandreportinginLevelSpaceisconceptuallyprettystraightforward:Youpassblocksofcodetochildmodels,andthechildmodelsrespondasifyouhadtypedthatcodeintotheirCommandCenter.LevelSpaceallowsyoutoreportstrings,numbers,andlistsfromachildtoitsparent.Itisnotpossibletodirectlyreportturtles,patches,links,oranyoftheirrespectivesets.Further,itisnotpossibletopushdatafromachildtoitsparent-parentsmustasktheirchildrentoreport.Thismimicksthewayinwhichturtlescannot“push”datatotheobserver,butrelyontheobservertoaskthemforit.

Ingeneral,theLevelSpacesyntaxhasbeendesignedtoalignwithexistingNetLogoprimitiveswheneverpossible.

HeadlessandInteractiveModels

LevelSpacehastwodifferentchildmodeltypes;headlessmodelsandinteractivemodels.Theyeachhavetheirstrengthsandweaknesses:

Interactivemodels*arefull-fledgedmodelsthatgivefullaccesstotheirinterfaceandwidgets,*runabitslower,andusemorememory*arevisiblebydefault

HeadlessModels*onlygiveyouaccesstotheirviewandcommandcenter*arefasteranduselessmemorythaninteractivemodels.*arehiddenbydefault

Typicallyyouwillwanttouseheadlessmodelswhenyouarerunningalargenumberofmodels,orifyousimplywanttorunthemfaster.Interactivemodelsaregoodifyourunasmallamountofmodels,ifyouarewritingaLevelSpacemodelandneedtobeabletodebug,orifyouneedaccesstowidgetsduringruntime.

KeepingTrackofModels

Childmodelsarekepttrackofintheextensionwithanidnumber,startingwith0,andallcommunicationfromparenttochildisdonebyreferencingthisnumber,henceforthreferredtoasmodel-id.

Theeasiestwaytoworkwithmultiplemodelsistostoretheirmodel-idinalist,anduseNetLogo’slistprimitivestosort,filter,etc.themduringruntime.

Keepingtrackofmodelsisimportant:MostLevelSpaceprimitiveswillfailandcausearuntimeinterruptionifprovidedamodel-idtoanon-existingmodel.Youcanusels:model-exists? model-idtocheckifmodel-idreferstoanexistingmodel.

Ageneralusecase:AskingandReporting

ThisusecaseisbasedontheModelVisualizerandPlotterExample-modelfromtheNetLogoModelsLibrary.

Asimplethingwecandoistoopenupsomemodels,runthemconcurrently,andcalculatetheaverageofsomereporter.Let’ssaythatweareinterestedinfindingthemeannumberofsheepinabunchofWolfSheepPredationmodels.Firstwewouldopenupsomeofthesemodels,andsetthemup:

to setup ls:reset ca ls:create-models 30 "Wolf Sheep Predation.nlogo" ls:ask ls:models [ set grass? true setup ] reset-ticksend

Wethenwanttorunallourchildmodels,andthenfindoutwhatthemeannumberofsheepis:

to go ls:ask ls:models [ go ] show mean [ count sheep ] ls:of ls:modelsend

Ageneralusecase:Inter-ModelInteractions

ThisusecaseisbasedontheModelInteractionsExample-modelfromtheNetLogoModelsLibrary.

Let’simaginethatwehavetwomodels:aWolfSheepPredation-modelcalledWSP,andaClimateChangemodelcalledCC.Nowlet’simaginethatwewanttheregrowthtimeinthewSPmodeltodependonthetemperatureintheCCmodel.UsingLevelSpace’sprimitives,wecoulddosomethinglikethis:

; save new regrowth time in a temporary LevelSpace let-variable ls:let new-regrowth-time 25 + ( abs [ temperature - 55 ] ls:of CC ) / 2

; remove decimals, pass it to the wolf sheep predation model and change the time ls:ask WSP [ set grass-regrowth-time round new-regrowth-time ]

; finally ask both models to go ls:ask ls:models [ go ]

AgeneralUsecase:Tidyingup“Dead”ChildModels

Aspreviouslymentioned,itisimportanttokeeptrackof“living”and“dead”modelswhenyoudynamicallycreateanddisposeofmodels.Letusimaginewehavesomelistsofmodelsofdifferentkinds,andwewanttomakesurethatweonlykeepthemodelsthatarealive.Afterrunningcodethatkillschildmodelswecanusethels:model-exists?primitivetocleanupourlistofmodelslikethis:

to-report remove-dead-models [list-of-models] report filter [ [ model-id ] -> ls:model-exists model-id] list-of-modelsend

Wethenreassigneachlistofmodelswiththis,e.g.

set a-list-of-models remove-dead-models a-list-of-modelsset another-list-of-models remove-dead-models a-list-of-models

CitingLevelSpaceinResearch

IfyouuseLevelSpaceinresearch,weaskthatyouciteus,

Hjorth,A.Head,B.&Wilensky,U.(2015).“LevelSpaceNetLogoextension”.http://ccl.northwestern.edu/rp/levelspace/index.shtmlEvanston,IL:CenterforConnectedLearningandComputerBasedModeling,NorthwesternUniversity.

Primitives

CommandingandReporting

ls:askls:ofls:reportls:withls:let

LogicandControl

ls:modelsls:showls:show-allls:hidels:hide-allls:path-ofls:name-ofls:model-exists?

OpeningandClosingModels

ls:create-modelsls:create-interactive-modelsls:closels:reset

ls:create-models

ls:create-modelsnumberpathls:create-modelsnumberpathanonymouscommand

Createthespecifiednumberofinstancesofthegiven.nlogomodel.Thepathcanbeabsolute,orrelativetothemainmodel.Comparedwithls:create-interactive-models,thisprimitivecreateslightweightmodelsthatarehiddenbydefault.Youshouldusethisprimitiveifyouplanonhavingmanyinstancesofthegivenmodel.Themodelsmaybeshownusingls:show;whenvisible,theywillhaveaviewandcommandcenter,butnootherwidgets,e.g.plotsormonitors.

Ifgivenacommand,LevelSpacewillcallthecommandafterloadingeachinstanceofthemodelwiththemodel-idastheargument.Thisallowsyoutoeasilystoremodelidsinavariableorlistwhenloadingmodels,ordootherinitialization.Forexample,tostoreamodelidinavariable,youcando:

let model-id 0(ls:create-models "My-Model.nlogo" [ [id] -> set model-id id ])

ls:create-interactive-models

ls:create-interactive-modelsnumberpathls:create-interactive-modelsnumberpathanonymouscommand

Likels:create-models,createsthespecifiednumberofinstancesofthegiven.nlogo

http://ccl.northwestern.edu/rp/levelspace/index.shtml

model.Unlikels:create-models,ls:create-interactive-modelscreatesmodelsthatarevisiblebydefault,andhaveallwidgets.Youshouldusethisprimitiveifyouplanonhavingonlyahandfulofinstancesofthegivenmodel,andwouldliketobeabletointeractwiththeinstancesthroughtheirinterfacesduringruntime.

ls:close

ls:closemodel-or-list-of-models

Closethemodelormodelswiththegivenmodel-id.

ls:reset

ls:reset

Closedownallchildmodels(and,recursively,theirchildmodels).You’lloftenwanttocallthisinyoursetupprocedure.

Notethatclear-alldoesnotcloseLevelSpacemodels.

ls:ask

ls:askmodel-or-list-of-modelscommandargument

Askthegivenchildmodelorlistofchildmodelstorunthegivencommand.Thisistheprimaryofdoingthingswithchildmodels.Forexample:

ls:ask model-id [ create-turtles 5 ]

Youcanalsoaskalistofmodelstoalldothesamething:

ls:ask ls:models [ create-turtles 5 ]

Youmaysupplythecommandwitharguments,justlikeyouwouldwithanonymouscommands:

let turtle-id 0let speed 5(ls:ask model-id [ [t s] -> ask turtle t [ fd s ] ] turtle-id speed)

Notethatthecommandscannotaccessvariablesintheparentmodeldirectly.Youmusteitherpassinformationinthroughargumentsorusingls:let.

ls:of

reporterls:ofmodel-or-list-of-models

Runthegivenreporterinthegivenmodelandreporttheresult.

ls:ofisdesignedtoworklikeNetLogo’sinbuiltof:Ifyousendls:ofamodel-id,itwillreportthevalueofthereporterfromthatmodel.Ifyousenditalistofmodel-ids,itwill

reportalistofvaluesofthereporterstringfromallmodels.Youcannotpassargumentstols:of,butyoucanusels:let.

[ count turtles ] ls:of model-id

ls:report

ls:reportmodel-or-list-of-modelsreporterargument

Runthegivenreporterinthegivenmodelandreporttheresult.Thisformexiststoallowyoutopassargumentstothereporter.

let turtle-id 0(ls:report model-id [ [a-turtle] -> [ color ] of turtle a-turtle ] turtle-id)

ls:with

list-of-modelsls:withreporter

Reportsanewlistofmodelscontainingonlythosemodelsthatreporttruewhentheyrunthereporterblock.

ls:models ls:with [ count turtles > 100 ]

ls:let

ls:letvariable-namevalue

Createsavariablecontainingthegivendatathatcanbeaccessedbythechildmodels.

ask turtles [ ls:let my-color color ls:ask my-model [ ask turtles [ set color my-color ] ]]

ls:letworksquitesimilartoletinthatthevariableisonlylocallyaccessible:

ask turtles [ ls:let my-color color];; my-color is innaccessible here

ls:letisverysimilartolet,exceptinafewcases.

ls:letwilloverwritepreviousvaluesinthevariable

Ifyoudo

ls:let my-var 5

ls:let my-var 6

my-varwillbesetequalto6.Thereisnols:set.

ls:letsupportsvariableshadowing

Ifyoudo

ls:let my-var 5ask turtles [ ls:let my-var 6 ls:ask child-model [ show my-var ]]ls:ask child-model [ show my-var ]

child-modelwillshow6andthen5.Thisisknownasvariableshadowing.

Theparentmodelcannotdirectlyreadthevalueofanlsvariable

Forexample,thisdoesnotwork.

ls:let my-var 5show my-var

Thisisintentional.lsvariablesaremeanttobeusedforsharingdatawithchildmodels.Theparentmodelalreadyhasaccesstothedata.

Furthermore,changingthevalueofanlsletvariableinachildmodelwillnotaffectitinanyothermodel.Forexample:

ls:let my-var 0ls:ask ls:models [ set my-var my-var + 1 show my-var]

Allmodelswillprint1.

ls:letdoesnotrespectthescopeofif,when,andrepeat

Thisbehaviorshouldbeconsideredabugandnotreliedupon.ItisanunfortunateconsequenceofthewaytheNetLogoengineworks.Hopefully,we’llbeabletocorrectthisinafutureversionofNetLogo.

Forexample,thisisallowable:

if true [ ls:let my-var 5]ls:ask child-model [ create-turtles my-var ]

Thescopeofaskisrespected,however.

ls:models

ls:models

https://en.wikipedia.org/wiki/Variable_shadowing

Reportalistofmodel-idsforallexistingmodels.

ls:show

ls:showmodel-or-list-of-models

Makesallofthegivenmodelsvisible.

ls:show-all

ls:show-allmodel-or-list-of-models

Makesallofthegivenmodelsandtheirdescendentsvisible.

ls:hide

ls:hidemodel-or-list-of-models

Hideallofthegivenmodels.Hidingmodelsisagoodwayofmakingyoursimulationrunfaster.

ls:hide-all

ls:hide-allmodel-or-list-of-models

Hideallofthegivenmodelsandtheirdescendents.Hidingmodelsisagoodwayofmakingyoursimulationrunfaster.

ls:path-of

ls:path-ofmodel-or-list-of-models

Reportthefullpath,includingthe.nlogofilename,ofthemodel.Ifalistofmodelsisgiven,alistofpathsisreported.

ls:name-of

ls:name-ofmodel-or-list-of-models

Reportsthenameofthe.nlogofileofthemodel.Thisisthenameofthewindowinwhichthemodelappearswhenvisible.Ifalistofmodelsisgiven,alistofnamesisreported.

ls:model-exists?

ls:model-exists?model-or-list-of-models

Reportabooleanvalueforwhetherthereisamodelwiththatmodel-id.Thisisoftenusefulwhenyouaredynamicallygeneratingmodels,andwanttoensurethatyouarenotaskingmodelsthatnolongerexisttodostuff.

NetLogoMatrixExtension

Using

ThematrixextensionaddsanewmatrixdatastructuretoNetLogo.Amatrixisamutable2-dimensionalarraycontainingonlynumbers.

WhentoUse

Althoughmatricesstorenumbers,muchlikealistoflists,oranarrayofarrays,theprimaryreasontousethematrixdatatypeistotakeadvantageofspecialmathematicaloperationsassociatedwithmatrices.Forinstance,matrixmultiplicationisaconvenientwaytoperformgeometrictransformations,andtherepeatedapplicationofmatrixmultiplicationcanalsobeusedtosimulateotherdynamicprocesses(forinstance,processesongraph/networkstructures).

Ifyou’dliketoknowmoreaboutmatricesandhowtheycanbeused,youmightconsideracourseonlinearalgebra,orsearchthewebfortutorials.Thematrixextensionalsoallowsyoutosolvelinearalgebraicequations(specifiedinamatrixformat),andeventoidentifytrendsinyourdataandperformlinear(ordinaryleastsquares)regressionsondatasetswithmultipleexplanatoryvariables.

HowtoUse

Thematrixextensioncomespreinstalled.

Tousethematrixextensioninyourmodel,addalinetothetopofyourCodetab:

extensions [matrix]

Ifyourmodelalreadyusesotherextensions,thenitalreadyhasanextensionslineinit,sojustaddmatrixtothelist.

Example

let m matrix:from-row-list [[1 2 3] [4 5 6]]print m=> {{matrix: [ [ 1 2 3 ][ 4 5 6 ] ]}}print matrix:pretty-print-text m=>[[ 1 2 3 ] [ 4 5 6 ]]

print matrix:dimensions m=> [2 3];;(NOTE: row & column indexing starts at 0, not 1)print matrix:get m 1 2 ;; what number is in row 1, column 2?=> 6matrix:set m 1 2 10 ;; change the 6 to a 10print m=> {{matrix: [ [ 1 2 3 ][ 4 5 10 ] ]}}

let m2 matrix:make-identity 3print m2=> {{matrix: [ [ 1 0 0 ][ 0 1 0 ][ 0 0 1 ] ]}}print matrix:times m m2 ;; multiplying by the identity changes nothing=> {{matrix: [ [ 1 2 3 ][ 4 5 10 ] ]}}

;; make a new matrix with the middle 1 changed to -1let m3 (matrix:set-and-report m2 1 1 -1)print m3=> {{matrix: [ [ 1 0 0 ][ 0 -1 0 ][ 0 0 1 ] ]}}print matrix:times m m3=> {{matrix: [ [ 1 -2 3 ][ 4 -5 10 ] ]}}

print matrix:to-row-list (matrix:plus m2 m3)=> [[2 0 0] [0 0 0] [0 0 2]]

Primitives

Matrixcreationandconversionto/fromlists

matrix:make-constantmatrix:make-identitymatrix:from-row-listmatrix:from-column-listmatrix:to-row-listmatrix:to-column-listmatrix:copymatrix:pretty-print-text

Advancedfeatures

matrix:solvematrix:forecast-linear-growthmatrix:forecast-compound-growthmatrix:forecast-continuous-growthmatrix:regress

Matrixdataretrievalandmanipulation

matrix:getmatrix:get-rowmatrix:get-columnmatrix:setmatrix:set-rowmatrix:set-columnmatrix:swap-rowsmatrix:swap-columnsmatrix:set-and-reportmatrix:dimensionsmatrix:submatrixmatrix:map

Mathoperations

matrix:times-scalarmatrix:timesmatrix:*matrix:times-element-wisematrix:plus-scalarmatrix:plusmatrix:+matrix:minusmatrix:-matrix:inversematrix:transposematrix:real-eigenvaluesmatrix:imaginary-eigenvaluesmatrix:eigenvectorsmatrix:detmatrix:rankmatrix:trace

matrix:make-constant

matrix:make-constantn-rowsn-colsinitialValue

Reportsanewn-rowsbyn-colsmatrixobject,withallentriesinthematrixcontainingthesamevalue(number).

matrix:make-identity

matrix:make-identitysize

Reportsanewsquarematrixobject(withdimensionsn-sizexn-size),consistingoftheidentitymatrix(1salongthemaindiagonal,0selsewhere).

matrix:from-row-list

matrix:from-row-listnested-list

Reportsanewmatrixobject,createdfromaNetLogolist,whereeachiteminthatlistisanotherlist(correspondingtoeachoftherowsofthematrix.)

print matrix:from-row-list [[1 2] [3 4]]=> {{matrix: [ [ 1 2 ][ 3 4 ] ]}};; Corresponds to this matrix:;; 1 2;; 3 4

matrix:from-column-list

matrix:from-column-listnested-list

Reportsanewmatrixobject,createdfromaNetLogolistcontainingeachofthecolumnsofthematrix.

matrix:to-row-list

matrix:to-row-listmatrix

Reportsalistoflists,containingeachrowofthematrix.

matrix:to-column-list

matrix:to-column-listmatrix

Reportsalistoflists,containingeachcolumnofthematrix.

matrix:copy

matrix:copymatrix

Reportsanewmatrixthatisanexactcopyofthegivenmatrix.Thisprimitiveisimportantbecausethematrixtypeismutable(changeable).Here’sacodeexample:

let m1 matrix:from-column-list [[1 4 7][2 5 8][3 6 9]] ; a 3x3 matrixprint m1=> {{matrix: [ [ 1 2 3 ][ 4 5 6 ][ 7 8 9 ] ]}}let m2 m1 ;; m2 refers to the same matrix object as m1let m3 matrix:copy m1 ;; m3 is a new copy containing m1's data

matrix:set m1 0 0 100 ;; now m1 is changed

print m1=> {{matrix: [ [ 100 2 3 ][ 4 5 6 ][ 7 8 9 ] ]}}

print m2=> {{matrix: [ [ 100 2 3 ][ 4 5 6 ][ 7 8 9 ] ]}};;Notice that m2 was also changed, when m1 was changed!

print m3=> {{matrix: [ [ 1 2 3 ][ 4 5 6 ][ 7 8 9 ] ]}}

matrix:pretty-print-text

matrix:pretty-print-textmatrix

Reportsastringthatisatextualrepresentationofthematrix,inaformatthatisreasonablyhuman-readablewhendisplayed.

matrix:get

matrix:getmatrixrow-icol-j

Reportsthe(numeric)valueatlocationrow-i(secondargument),col-j(thirdargument),inthegivenmatrixgiveninthefirstargument

matrix:get-row

matrix:get-rowmatrixrow-i

Reportsasimple(notnested)NetLogolistcontainingtheelementsofrow-i(secondargument)ofthematrixsuppliedinthefirstargument.

matrix:get-column

matrix:get-columnmatrixcol-j

Reportsasimple(notnested)NetLogolistcontainingtheelementsofcol-jofthematrixsuppliedinthefirstargument.

matrix:set

matrix:setmatrixrow-icol-jnew-value

Changesthegivenmatrixbysettingthevalueatlocationrow-i,col-jtonew-value

matrix:set-row

matrix:set-rowmatrixrow-isimple-list

Changesthegivenmatrixmatrixbyreplacingtherowatrow-iwiththecontentsofthesimple(notnested)NetLogolistsimple-list.Thesimple-listmusthavealengthequaltothenumberofcolumnsinthematrix,i.e.,thematrixrowlength.

matrix:set-column

matrix:set-columnmatrixcol-jsimple-list

Changesthegivenmatrixmatrixbyreplacingthecolumnatcol-jwiththecontentsofthesimple(notnested)NetLogolistsimple-list.Thesimple-listmusthavealengthequaltothenumberofrowsinthematrix,i.e.,thematrixcolumnlengthlength.

matrix:swap-rows

matrix:swap-rowsmatrixrow1row2

Changesthegivenmatrixmatrixbyswappingtherowsatrow1androw2witheachother.

matrix:swap-columns

matrix:swap-columnsmatrixcol1col2

Changesthegivenmatrixmatrixbyswappingthecolumnsatcol1andcol2witheachother.

matrix:set-and-report

matrix:set-and-reportmatrixrow-icol-jnew-value

Reportsanewmatrix,whichisacopyofthegivenmatrixexceptthatthevalueatrow-i,col-jhasbeenchangedtonew-value.ANetLogostatementsuchasset mat matrix:set-and-report mat 2 3 10willresultinmatpointingtothisnewmatrix,acopyoftheoldversionofmatwiththeelementatrow2,column3beingsetto10.Theoldversionofmatwillbe“lost”.

matrix:dimensions

matrix:dimensionsmatrix

Reportsa2-elementlist([num-rows,num-cols]),containingthenumberofrowsandnumberofcolumnsinthegivenmatrix

matrix:submatrix

matrix:submatrixmatrixr1c1r2c2

Reportsanewmatrixobject,consistingofarectangularsubsectionofthegivenmatrix.Therectangularregionisfromrowr1upto(butnotincluding)rowr2,andfromcolumnc1upto(butnotincluding)columnc2.

Hereisanexample:

let m matrix:from-row-list [[1 2 3][4 5 6][7 8 9]]print matrix:submatrix m 0 1 2 3 ; matrix, row-start, col-start, row-end, col-end ; rows from 0 (inclusive) to 2 (exclusive), ; columns from 1 (inclusive) to 3 (exclusive)=> {{matrix: [ [ 2 3 ][ 5 6 ] ]}}

matrix:map

matrix:mapanonymousreportermatrixmatrix:mapanonymousreportermatrixanything

Reportsanewmatrixwhichresultsfromapplyingreporter(ananonymousreporterorthenameofareporter)toeachoftheelementsofthegivenmatrix.Forexample,

matrix:map sqrt matrix

wouldtakethesquarerootofeachelementofmatrix.Ifmorethanonematrixargumentisprovided,thereporterisgiventheelementsofeachmatrixasarguments.Thus,

(matrix:map + matrix1 matrix2)

wouldaddmatrix1andmatrix2.

Thisreporterismeanttobethesameasmap,butformatricesinsteadoflists.

matrix:times-scalar

matrix:times-scalarmatrixfactor

AsofNetLogo5.1,matrix:timescanmultiplymatricesbyscalarsmakingthisfunctionobsolete.Usematrix:timesinstead.

Reportsanewmatrix,whichistheresultofmultiplyingeveryentryintheoriginalmatrixbythegivenscalingfactor.

matrix:times

matrix:timesm1m2matrix:timesm1m2...

Reportsamatrix,whichistheresultofmultiplyingthegivenmatricesandscalars(usingstandardmatrixmultiplication–makesureyourmatrixdimensionsmatchup.)Withoutparentheses,ittakestwoarguments.Withparenthesesittakestwoormore.Theargumentsmayeitherbenumbersormatrices,butatleastonemustbeamatrix.

matrix:*

m1matrix:*m2

Reportsamatrix,whichistheresultofmultiplyingthegivenmatricesand/orscalars(usingstandardmatrixmultiplication–makesureyourmatrixdimensionsmatchup.)Thisisexactlythesameasmatrix:times m1 m2

Takesprecedenceovermatrix:+andmatrix:-,sameasnormalmultiplication.

matrix:times-element-wise

matrix:times-element-wisem1m2

Reportsamatrix,whichistheresultofmultiplyingthegivenmatricestogether,element-wise.Allelementsaremultipliedbyscalarargumentsaswell.Notethatallmatrixargumentsmusthavethesamedimensions.Withoutparentheses,ittakestwoarguments.Withparenthesesittakestwoormore.Theargumentsmayeitherbenumbersormatrices,butatleastonemustbeamatrix.

matrix:plus-scalar

matrix:plus-scalarmatrixnumber

AsofNetLogo5.1,matrix:pluscanaddmatricesandscalarsmakingthisfunctionobsolete.Usematrix:plusinstead.

Reportsamatrix,whichistheresultofaddingtheconstantnumbertoeachelementofthegivenmatrix.

matrix:plus

matrix:plusm1m2matrix:plusm1m2...

Reportsamatrix,whichistheresultofaddingthegivenmatricesandscalars.Scalarsareaddedtoeachelement.Withoutparentheses,ittakestwoarguments.Withparenthesesittakestwoormore.Theargumentsmayeitherbenumbersormatrices,butatleastonemustbeamatrix.

matrix:+

m1matrix:+m2

Reportsamatrix,whichistheresultofaddingthegivenmatricesand/orscalars.Thisisexactlythesameasmatrix:plusm1 m2

Takesprecedenceaftermatrix:*,sameasnormaladdition.

matrix:minus

matrix:minusm1m2matrix:minusm1m2...

Reportsamatrix,whichistheresultofsubtractingallargumentsbesidesm1fromm1.Scalarargumentsaretreatedasmatricesofthesamesizeasthematrixargumentswitheveryelementequaltothatscalar.Withoutparentheses,ittakestwoarguments.Withparenthesesittakestwoormore.Theargumentsmayeitherbenumbersormatrices,butatleastonemustbeamatrix.

matrix:-

m1matrix:-m2

Reportsamatrix,whichistheresultofsubtractingthegivenmatricesand/orscalars.Thisisexactlythesameas

matrix:minus m1 m2

Takesprecedenceaftermatrix:*,sameasnormalsubtraction.

matrix:inverse

matrix:inversematrix

Reportstheinverseofthegivenmatrix,orresultsinanerrorifthematrixisnotinvertible.

matrix:transpose

matrix:transposematrix

Reportsthetransposeofthegivenmatrix.

matrix:real-eigenvalues

matrix:real-eigenvaluesmatrix

Reportsalistcontainingtherealeigenvaluesofthegivenmatrix.

matrix:imaginary-eigenvalues

matrix:imaginary-eigenvaluesmatrix

Reportsalistcontainingtheimaginaryeigenvaluesofthegivenmatrix.

matrix:eigenvectors

matrix:eigenvectorsmatrix

Reportsamatrixthatcontainstheeigenvectorsofthegivenmatrix.(Eacheigenvectorasacolumnoftheresultingmatrix.)

matrix:det

matrix:detmatrix

Reportsathedeterminantofthematrix.

matrix:rank

matrix:rankmatrix

Reportstheeffectivenumericalrankofthematrix,obtainedfromSVD(SingularValueDecomposition).

matrix:trace

matrix:tracematrix

Reportsthetraceofthematrix,whichissimplythesumofthemaindiagonalelements.

matrix:solve

matrix:solveAC

Reportsthesolutiontoalinearsystemofequations,specifiedbytheAandCmatrices.Ingeneral,solvingasetoflinearequationsisakintomatrixdivision.Thatis,thegoalistofindamatrixBsuchthatA*B=C.(Forsimplelinearsystems,CandBcanbothbe1-dimensionalmatrices–i.e.vectors).IfAisnotasquarematrix,thena“leastsquares”solutionisreturned.

;; To solve the set of equations x + 3y = 10 and 7x - 4y = 20;; We make our A matrix [[1 3][7 -4]], and our C matrix [[10][20]]let A matrix:from-row-list [[1 3][7 -4]]let C matrix:from-row-list [[10][20]]print matrix:solve A C=> {{matrix: [ [ 4 ][ 2.0000000000000004 ] ]}};; NOTE: as you can see, the results may be only approximate;; (In this case, the true solution should be x=4 and y=2.)

matrix:forecast-linear-growth

matrix:forecast-linear-growthdata-list

Reportsafour-elementlistoftheform:

[ forecast constant slope R2 ]

Theforecastisthepredictednextvaluethatwouldfollowinthesequencegivenbythedata-listinput,basedonalineartrend-line.Normallydata-listwillcontainobservationsonsomevariable,Y,fromtimet=0totimet=(n-1)wherenisthenumberofobservations.TheforecastisthepredictedvalueofYatt=n.Theconstantandslopearetheparametersofthetrend-line

Y = *constant* + *slope* * t.

TheR2valuemeasuresthegoodnessoffitofthetrend-linetothedata,withanR2=1beingaperfectfitandanR2of0indicatingnodiscernibletrend.LineargrowthassumesthatthevariableYgrowsbyaconstantabsoluteamounteachperiod.

;; a linear extrapolation of the next item in the list.print matrix:forecast-linear-growth [20 25 28 32 35 39]=> [42.733333333333334 20.619047619047638 3.6857142857142824 0.9953743395474031];; These results tell us:;; * the next predicted value is roughly 42.7333;; * the linear trend line is given by Y = 20.6190 + 3.6857 * t;; * Y grows by approximately 3.6857 units each period;; * the R^2 value is roughly 0.9954 (a good fit)

matrix:forecast-compound-growth

matrix:forecast-compound-growthdata-list


[ forecast constant growth-proportion R2 ]

Whereasmatrix:forecast-linear-growthassumesgrowthbyaconstantabsoluteamounteachperiod,matrix:forecast-compound-growthassumesthatYgrowsbyaconstantproportioneachperiod.Theconstantandgrowth-proportionaretheparametersofthetrend-line

Y = constant * growth-proportiont.

Notethatthegrowthproportionistypicallyinterpretedasgrowth-proportion=(1.0+growth-rate).Therefore,ifmatrix:forecast-compound-growthreturnsagrowth-proportionof1.10,thatimpliesthatYgrowsby(1.10-1.0)=10%eachperiod.Notethatifgrowthisnegative,matrix:forecast-compound-growthwillreturnagrowth-proportionoflessthanone.E.g.,agrowth-proportionof0.90impliesagrowthrateof-10%.

NOTE:ThecompoundgrowthforecastisachievedbytakingthelnofY.(Seematrix:regress,below.)Becauseitisimpossibletotakethenaturallogofzerooranegativenumber,matrix:forecast-compound-growthwillresultinanerrorifitfindsazeroornegativenumberindata-list.

;; a compound growth extrapolation of the next item in the list.print matrix:forecast-compound-growth [20 25 28 32 35 39]=> [45.60964465307147 21.15254147944863 1.136621034423892 0.9760867518334806];; These results tell us:;; * the next predicted value is approximately 45.610;; * the compound growth trend line is given by Y = 21.1525 * 1.1366 ^ t;; * Y grows by approximately 13.66% each period;; * the R^2 value is roughly 0.9761 (a good fit)

matrix:forecast-continuous-growth

matrix:forecast-continuous-growthdata-list


[ forecast constant growth-rate R2 ].Whereasmatrix:forecast-compound-growthassumesdiscretetimewithYgrowingbyagivenproportioneachfiniteperiodoftime(e.g.,amonthorayear),matrix:forecast-continuous-growthassumesthatYiscompoundedcontinuously(e.g.,eachsecondorfractionofasecond).Theconstantandgrowth-ratearetheparametersofthetrend-line

Y = constant * e(growth-rate * t)

matrix:forecast-continuous-growthisthe“calculus”analogofmatrix:forecast-compound-growth.Thetwowillnormallyyieldsimilar(butnotidentical)results,asshownintheexamplebelow.growth-ratemay,ofcourse,benegative.

NOTE:ThecontinuousgrowthforecastisachievedbytakingthelnofY.(Seematrix:regress,below.)Becauseitisimpossibletotakethenaturallogofzerooranegativenumber,matrix:forecast-continuous-growthwillresultinanerrorifitfindsazeroornegativenumberindata-list.

;; a continuous growth extrapolation of the next item in the list.print matrix:forecast-continuous-growth [20 25 28 32 35 39]=> [45.60964465307146 21.15254147944863 0.12805985615332668 0.9760867518334806];; These results tell us:;; * the next predicted value is approximately 45.610;; * the compound growth trend line is given by Y = 21.1525 * e ^ (0.1281 * t);; * Y grows by approximately 12.81% each period if compounding takes place continuously;; * the R^2 value is roughly 0.9761 (a good fit)

matrix:regress

matrix:regressdata-matrix

AllthreeoftheforecastprimitivesabovearejustspecialcasesofperforminganOLS(ordinary-least-squares)linearregression–thematrix:regressprimitiveprovidesaflexible/general-purposeapproach.Theinputisamatrixdata-matrix,withthefirstcolumnbeingtheobservationsonthedependentvariableandeachsubsequentcolumnbeingtheobservationsonthe(1ormore)independentvariables.Thuseachrowconsistsofanobservationofthedependentvariablefollowedbythecorrespondingobservationsforeachindependentvariable.

TheoutputisaLogonestedlistcomposedoftwoelements.Thefirstelementisalistcontainingtheregressionconstantfollowedbythecoefficientsoneachoftheindependentvariables.Thesecondelementisa3-elementlistcontainingtheR2statistic,thetotalsumofsquares,andtheresidualsumofsquares.Thefollowingcodeexampleshowshowthematrix:regressprimitivecanbeusedtoperformthesamefunctionasthecodeexamplesshowninthematrix:forecast-*-growthprimitivesabove.(However,keepinmindthatthematrix:regressprimitiveismorepowerfulthanthis,andcanhavemanymoreindependentvariablesintheregression,asindicatedinthefourthexamplebelow.)

;; this is equivalent to what the matrix:forecast-linear-growth doeslet data-list [20 25 28 32 35 39]let indep-var (n-values length data-list [ x -> x ]) ; 0,1,2...,5let lin-output matrix:regress matrix:from-column-list (list data-list indep-var)let lincnst item 0 (item 0 lin-output)let linslpe item 1 (item 0 lin-output)let linR2 item 0 (item 1 lin-output);;Note the "6" here is because we want to forecast the value at time t=6.print (list (lincnst + linslpe * 6) (lincnst) (linslpe) (linR2))

;; this is equivalent to what the matrix:forecast-compound-growth doeslet com-log-data-list (map ln [20 25 28 32 35 39])let com-indep-var2 (n-values length com-log-data-list [ x -> x ]) ; 0,1,2...,5let com-output matrix:regress matrix:from-column-list (list com-log-data-list com-indep-var2)let comcnst exp item 0 (item 0 com-output)let comprop exp item 1 (item 0 com-output)let comR2 item 0 (item 1 com-output);;Note the "6" here is because we want to forecast the value at time t=6.print (list (comcnst * comprop ^ 6) (comcnst) (comprop) (comR2))

;; this is equivalent to what the matrix:forecast-continuous-growth doeslet con-log-data-list (map ln [20 25 28 32 35 39])let con-indep-var2 (n-values length con-log-data-list [ x -> x ]) ; 0,1,2...,5let con-output matrix:regress matrix:from-column-list (list con-log-data-list con-indep-var2)let concnst exp item 0 (item 0 con-output)let conrate item 1 (item 0 con-output)let conR2 item 0 (item 1 con-output)print (list (concnst * exp (conrate * 6)) (concnst) (conrate) (conR2))

;; example of a regression with two independent variables:;; Pretend we have a dataset, and we want to know how well happiness;; is correlated to snack-food consumption and accomplishing goals.let happiness [2 4 5 8 10]let snack-food-consumed [3 4 3 7 8]let goals-accomplished [2 3 5 8 9]print matrix:regress matrix:from-column-list (list happiness snack-food-consumed goals-accomplished)=> [[-0.14606741573033788 0.3033707865168543 0.8202247191011234] [0.9801718440185063 40.8 0.8089887640449439]];; linear regression: happiness = -0.146 + 0.303*snack-food-consumed + 0.820*goals-accomplished;; (Since the 0.820 coefficient is higher than the 0.303 coefficient, it appears that each goal;; accomplished yields more happiness than does each snack consumed, although both are positively;; correlated with happiness.);; Also, we see that R^2 = 0.98, so the two factors together provide a good fit.

NetLogoNwExtension

Usage

Thefirstthingthatoneneedstounderstandinordertoworkwiththenetworkextensionishowtotelltheextensionwhichnetworktoworkwith.Considerthefollowingexamplesituation:

breed [ bankers banker ]breed [ clients client ]

undirected-link-breed [ friendships friendship ]directed-link-breed [ accounts account ]

Basically,youhavebankersandclients.Clientscanhaveaccountswithbankers.Bankerscanprobablyhaveaccountwithotherbankers,andanyonecanbefriendswithanyone.

Nowwemightwanttoconsiderthiswholethingasonebignetwork.Ifthatisthecase,thereisnothingspecialtodo:bydefault,theNWextensionprimitivesconsiderallturtlesandalllinkstobepartofthecurrentnetwork.

Wecouldalso,however,beonlyinterestedinasubsetofthenetwork.Maybewewanttoconsideronlyfriendshiprelations.Furthermore,maybewewanttoconsideronlythefriendshipsbetweenbankers.Afterall,havingaveryhighcentralityinanetworkofbankerfriendshipsisverydifferentfromhavingahighcentralityinanetworkofclientfriendships.

Tospecifysuchnetworks,weneedtotelltheextensionbothwhichturtlesandwhichlinksweareinterestedin.Alltheturtlesfromthespecifiedsetofturtleswillbeincludedinthenetwork,andonlythelinksfromthespecifiedsetoflinksthatarebetweenturtlesofthespecifiedsetwillbeincluded.Forexample,ifyouaskforbankersandfriendships,eventhelonelybankerswithnofriendswillbeincluded,butfriendshiplinksbetweenbankersandclientswillnotbeincluded.Thewaytotelltheextensionaboutthisiswiththenw:set-contextprimitive,whichyoumustcallpriortodoinganyoperationsonanetwork.

Someexamples:

nw:set-context turtles links willgiveyoueverything:bankersandclients,friendshipsandaccounts,asonebignetwork.nw:set-context turtles friendships willgiveyouallthebankersandclientsandfriendshipsbetweenanyofthem.nw:set-context bankers friendships willgiveyouallthebankers,andonlyfriendshipsbetweenbankers.nw:set-context bankers links willgiveyouallthebankers,andanylinksbetweenthem,whethertheselinksarefriendshipsoraccounts.nw:set-context clients accounts willgiveyoualltheclients,andaccountsbetweeneachother,butsinceinourfictionalexampleclientscanonlyhaveaccountswithbankers,thiswillbeacompletelydisconnectednetwork.

Specialagentsetsvsnormalagentsets

ItmustbenotedthatNetLogohastwotypesofagentsetsthatbehaveslightlydifferently,andthatthishasanimpactonthewaynw:set-contextworks.Wewillsayafewwordsabouttheseconceptsherebut,forathoroughunderstanding,itishighlyrecommendedthatyoureadthesectiononagentsetsintheNetLogoprogrammingguide.

The“special”agentsetsinNetLogoareturtles,linksandthedifferent“breed”agentsets.Whatisspecialaboutthemisthattheycangrow:ifyoucreateanewturtle,itwillbeaddedtotheturtlesagentset.Ifyouhaveabankersbreedandyoucreateanewbanker,itwillbeaddedtothebankersagentsetandtotheturtlesagentset.Samegoesforlinks.Otheragentsets,suchasthosecreatedwiththewithprimitive(e.g.,turtles with [ color = red ] )ortheturtle-setandlink-setprimitives)areneveraddedto.Thecontentofnormalagentsetswillonlychangeiftheagentsthattheycontaindie.

Toshowhowdifferenttypesofagentsetsinteractwithnw:set-context,let’screateaverysimplenetwork:

clear-allcreate-turtles 3 [ create-links-with other turtles ]

Let’ssetthecontexttoturtlesandlinks(whichisthedefaultanyway)andusenw:get-contexttoseewhatwehave:

nw:set-context turtles linksshow map sort nw:get-context

Wegetallthreeturtlesandallthreelinks:

[[(turtle 0) (turtle 1) (turtle 2)] [(link 0 1) (link 0 2) (link 1 2)]]

Nowlet’skilloneturtle:

ask one-of turtles [ die ]show map sort nw:get-context

Asexpected,thecontextisupdatedtoreflectthedeathoftheturtleandofthetwolinksthatdiedwithit:

[[(turtle 0) (turtle 1)] [(link 0 1)]]

Whatifwenowcreateanewturtle?

create-turtles 1show map sort nw:get-context

Sinceourcontextisusingthespecialturtlesagentset,thenewturtleisautomaticallyadded:

[[(turtle 0) (turtle 1) (turtle 3)] [(link 0 1)]]

Nowlet’sdemonstratehowitworkswithnormalagentsets.Westartoverwithanewnetworkofredturtles:

clear-allcreate-turtles 3 [ create-links-with other turtles set color red]

Andwesetthecontexttoturtles with [ color = red ]) andlinks

nw:set-context (turtles with [ color = red ]) linksshow map sort nw:get-context

Sinceallturtlesarered,wegeteverythinginourcontext:


Butwhatifweaskoneofthemtoturnblue?

ask one-of turtles [ set color blue ]show map sort nw:get-context

Nochange.Theagentsetusedinourcontextremainsunaffected:


Ifwekilloneofthem,however…

ask one-of turtles [ die ]show map sort nw:get-context

Itgetsremovedfromtheset:


Whatifweaddanewredturtle?

create-turtles 1 [ set color red ]show map sort nw:get-context

Nope:


Anoteregardingfloatingpointcalculations

NeitherJGraphTnorJung,thetwonetworklibrariesthatweuseinternally,usestrictfpfloatingpointcalculations.Thisdoesmeanthatexactreproducibilityofresultsinvolvingfloatingpointcalculationsbetweendifferenthardwarearchitecturesisnotfullyguaranteed.(NetLogoitselfalwaysusesstrictmathsothisonlyappliestosomeprimitivesoftheNWextension.)

Performance

Inordertobefastinasmanycircumstancesaspossible,theNWextensiontrieshardtonevercalculatethingstwice.Itremembersallpaths,distances,andcentralitiesthatitcalculates.So,whilethefirsttimeyouaskforthedistancebetweenturtle 0andturtle 3782maytakesometime,afterthat,itshouldbealmostinstantaneous.Furthermore,itkeepstrackofvaluesitjusthappenedtocalculatealongtheway.Forexample,ifturtle 297isclosertoturtle 0thanturtle 3782is,itmayjusthappentofigureoutthedistancebetweenturtle 0andturtle 297whileitfiguresoutthedistancebetweenturtle 0andturtle 3782.Itwillrememberthisvalue,sothatifyouaskitforthedistancebetweenturtle 0andturtle 297,itdoesn’thavetodoallthatworkagain.

ThereareafewcircumstanceswheretheNWextensionhastoforgetthings.Ifthenetworkchangesatall(youaddturtlesorlinks,orremoveturtlesorlinks),ithastoforgeteverything.Forweightedprimitives,ifthevalueoftheweightvariablechangesforanyofthelinksinthenetwork,itwillforgetthevaluesassociatedwiththatweightvariable.

Ifyou’reworkingonanetworkthatcanchangeregularly,trytodoallyournetworkcalculationsatonce,thenallyournetworkchangesatonce.Themoreyourinterweavenetworkcalculationsandnetworkchanges,themoretheNWextensionwillhavetorecalculatethings.Forexample,ifyouhaveatrafficmodel,andcarsneedtofigureouttheshortestpathtotheirdestinationbasedonthetrafficeachtick,haveallthecarsfindtheirshortestpaths,thenchangethenetworkweightstoaccountforhowtraffichaschanged.

Theremayberareoccasionsinwhichyoudon’twanttheNWextensiontoremembervalues.Forexample,ifyou’reworkingonanextremelylargenetwork,rememberingallthosevaluesmaytakemorememorythanyouhave.Inthatcase,youcanjustcallnw:set-context (first nw:get-context) (last nw:get-context) toforcetheNWextensiontoimmediatelyforgeteverything.

Primitives

Generators

nw:generate-preferential-attachmentnw:generate-randomnw:generate-watts-strogatznw:generate-small-worldnw:generate-lattice-2dnw:generate-ringnw:generate-starnw:generate-wheel

PathandDistance

nw:turtles-in-radiusnw:turtles-in-reverse-radiusnw:distance-tonw:weighted-distance-tonw:path-tonw:turtles-on-path-tonw:weighted-path-tonw:turtles-on-weighted-path-tonw:mean-path-lengthnw:mean-weighted-path-length

Clusterer/CommunityDetection

nw:bicomponent-clustersnw:weak-component-clustersnw:louvain-communitiesnw:maximal-cliquesnw:biggest-maximal-cliques

ContextManagement

nw:set-contextnw:get-contextnw:with-context

ImportandExport

nw:save-matrixnw:load-matrixnw:save-graphmlnw:load-graphmlnw:loadnw:save

CentralityMeasures

nw:betweenness-centralitynw:eigenvector-centralitynw:page-ranknw:closeness-centralitynw:weighted-closeness-centrality

ClusteringMeasures

https://github.com/jgrapht

http://jung.sourceforge.net/

http://en.wikipedia.org/wiki/Strictfp

nw:clustering-coefficientnw:modularity

nw:set-context

nw:set-contextturtlesetlinkset

Specifiesthesetofturtlesandthesetoflinksthattheextensionwillconsidertobethecurrentgraph.Alltheturtlesfromturtlesetandallthelinksfromlinksetthatconnecttwoturtlesfromturtlesetwillbeincluded.

Thiscontextisusedbyallotherprimitives(unlessspecifiedotherwise)untilanewcontextisspecified.(Atthemoment,onlythegeneratorprimitivesandthefileinputprimitivesareexceptionstothisrule.)

Seetheusagesectionforamuchmoredetailedexplanationofnw:set-context.

nw:get-context

nw:get-context

Reportsthecontentofthecurrentgraphcontextasalistcontainingtwoagentsets:theagentsetofturtlesthatarepartofthecontextandtheagentsetoflinksthatarepartofthecontext.

Let’ssaywestartwithablankslateandthedefaultcontextconsistingofturtlesandlinks,nw:get-contextwillreportalistthespecialturtlesandlinksbreedagentsets:

observer> clear-allobserver> show nw:get-contextobserver: [turtles links]

Ifweaddsometurtlesandlinkstoourcontext,we’llstillseethesamething,eventhoughturtlesandlinkshaveinternallygrown:

observer> crt 2 [ create-links-with other turtles ]observer> show nw:get-contextobserver: [turtles links]

Ifyouhadsetyourcontexttonormalagentsetsinstead(builtwithturtle-set,link-setorwith)hereiswhatyouwouldsee:

observer> clear-allobserver> nw:set-context turtle-set turtles link-set linksobserver> show nw:get-contextobserver: [(agentset, 0 turtles) (agentset, 0 links)]

Ifyouthencreatenewturtlesandlinks,theyarenotaddedtothecontextbecausenormalagentsetsdon’tgrow(seeSpecialagentsetsvsnormalagentsets):

observer> crt 2 [ create-links-with other turtles ]observer> show nw:get-contextobserver: [(agentset, 0 turtles) (agentset, 0 links)]

Butifyouconstructnewagentsetsandsetthecontexttothem,yournewagentswillbethere:

observer> nw:set-context turtle-set turtles link-set linksobserver> show nw:get-contextobserver: [(agentset, 2 turtles) (agentset, 1 link)]

Ifyouwanttoseetheactualcontentofyourcontext,itiseasytoturnyouragentsetsintoliststhatcanbenicelydisplayed.Justuseacombinationofmapandsort:

observer> show map sort nw:get-contextobserver: [[(turtle 0) (turtle 1)] [(link 0 1)]]

Finally,youcanusenw:get-contexttostoreacontextthatyoueventuallywanttorestore:

extensions [ nw ]to store-and-restore-context clear-all crt 2 [ set color red

create-links-with other turtles with [ color = red ] [ set color yellow ] ] crt 2 [ set color blue create-links-with other turtles with [ color = blue ] [ set color green ] ] nw:set-context turtles with [ color = red ] links with [ color = yellow ] show map sort nw:get-context let old-turtles item 0 nw:get-context let old-links item 1 nw:get-context nw:set-context turtles with [ color = blue ] links with [ color = green ] show map sort nw:get-context nw:set-context old-turtles old-links show map sort nw:get-contextend

Hereistheresult:

observer> store-and-restore-contextobserver: [[(turtle 0) (turtle 1)] [(link 0 1)]]observer: [[(turtle 2) (turtle 3)] [(link 2 3)]]observer: [[(turtle 0) (turtle 1)] [(link 0 1)]]

nw:with-context

nw:with-contextturtlesetlinksetcommand-block

Executesthecommand-blockwiththecontexttemporarilysettoturtlesetandlinkset.Aftercommand-blockfinishesrunning,thepreviouscontextwillberestored.

Forexample:

observer> create-turtles 3 [ create-links-with other turtles ]observer> nw:with-context (turtle-set turtle 0 turtle 1) (link-set link 0 1) [ show nw:get-context ]observer: [(agentset, 2 turtles) (agentset, 1 link)observer> show nw:get-contextobserver: [turtles links]

IfyouhaveNWextensioncoderunningintwoforeverbuttonsorloopblocksthateachneedtousedifferentcontexts,youshouldusenw:with-contextineachtomakesuretheyareoperatinginthecorrectcontext.

nw:turtles-in-radius

nw:turtles-in-radiusradius

Returnsthesetofturtleswithinthegivendistance(numberoflinksfollowed)ofthecallingturtleinthecurrentcontext,includingthecallingturtle.

nw:turtles-in-radiusformwillfollowbothundirectedlinksanddirectedoutlinks.Youcanthinkofturtles-in-radiusas“turtleswhoIcangettoinradiussteps”.

Ifyouwanttheprimitivetofollowonlyundirectedlinksoronlydirectedlinks,youcandoitbysettingthecontextappropriately.Forexample:nw:set-context turtles undir-links (assumingundir-linksisanundirectedlinkbreed)ornw:set-context turtles dir-links (assumingdir-linksisadirectedlinkbreed).

Example:

clear-allcreate-turtles 5ask turtle 0 [ create-link-with turtle 1 ]ask turtle 0 [ create-link-with turtle 2 ]ask turtle 1 [ create-link-with turtle 3 ]ask turtle 2 [ create-link-with turtle 4 ]ask turtle 0 [ show sort nw:turtles-in-radius 1]

Willoutput:

(turtle 0): [(turtle 0) (turtle 1) (turtle 2)]

Asyoumayhavenoticed,theresultincludesthecallingturtle.ThismimicsthebehavioroftheregularNetLogoin-radiusprimitive.

nw:turtles-in-reverse-radius

nw:turtles-in-reverse-radiusradius

Likenw:turtles-in-radius,butfollowsin-linksinsteadofout-links.Alsofollowundirectedlinks.Youcanthinkofturtles-in-reverse-radiusas“turtleswhocangettomeinradiussteps”.

nw:distance-to

nw:distance-totarget-turtle

Findstheshortestpathtothetargetturtleandreportsthetotaldistanceforthispath,orfalseifnopathexistsinthecurrentcontext.Eachlinkcountsforadistanceofone.

Example:

to go clear-all create-turtles 5 ask turtle 0 [ create-link-with turtle 1 ] ask turtle 1 [ create-link-with turtle 2 ] ask turtle 0 [ create-link-with turtle 3 ] ask turtle 3 [ create-link-with turtle 4 ] ask turtle 4 [ create-link-with turtle 2 ] ask turtle 0 [ show nw:distance-to turtle 2 ]end

Willoutput:

(turtle 0): 2

nw:weighted-distance-to

nw:weighted-distance-totarget-turtleweight-variable

Likenw:distance-to,buttakeslinkweightintoaccount.Theweightscannotbenegativenumbers.

Example:

links-own [ weight ]to go clear-all create-turtles 5 ask turtle 0 [ create-link-with turtle 1 [ set weight 2.0 ] ] ask turtle 1 [ create-link-with turtle 2 [ set weight 2.0 ] ] ask turtle 0 [ create-link-with turtle 3 [ set weight 0.5 ] ] ask turtle 3 [ create-link-with turtle 4 [ set weight 0.5 ] ] ask turtle 4 [ create-link-with turtle 2 [ set weight 0.5 ] ] ask turtle 0 [ show nw:weighted-distance-to turtle 2 weight ]end

Willoutput:

(turtle 0): 1.5

nw:path-to

nw:path-totarget-turtle

Findstheshortestpathtothetargetturtleandreportstheactualpathbetweenthesourceandthetargetturtle.Thepathisreportedasthelistoflinksthatconstitutethepath.

Ifnopathexistbetweenthesourceandthetargetturtles,falsewillbereportedinstead.

NotethattheNW-Extensionrememberspathsthatitscalculatedpreviouslyunlessthenetworkchanges.Thus,youdon’tneedtostorepathstoefficientlymoveacrossthenetwork;youcanjustkeepre-callingoneofthepathprimitives.Ifthenetworkchanges,however,thestoredanswersareforgotten.Example:

ccl.northwestern.edu/netlogo/docs/dictionary.html#in-radius

links-own [ weight ]to go clear-all create-turtles 5 ask turtle 0 [ create-link-with turtle 1 ] ask turtle 1 [ create-link-with turtle 2 ] ask turtle 0 [ create-link-with turtle 3 ] ask turtle 3 [ create-link-with turtle 4 ] ask turtle 4 [ create-link-with turtle 2 ] ask turtle 0 [ show nw:path-to turtle 2 ]end

Willoutput:

(turtle 0): [(link 0 1) (link 1 2)]

nw:turtles-on-path-to

nw:turtles-on-path-totarget-turtle

Likenw:path-to,buttheturtlesonthepatharereported,insteadofthelinks,includingthesourceturtleandtargetturtle.

Example:

to go clear-all create-turtles 5 ask turtle 0 [ create-link-with turtle 1 ] ask turtle 1 [ create-link-with turtle 2 ] ask turtle 0 [ create-link-with turtle 3 ] ask turtle 3 [ create-link-with turtle 4 ] ask turtle 4 [ create-link-with turtle 2 ] ask turtle 0 [ show nw:turtles-on-path-to turtle 2 ]end

Willoutput:

(turtle 0): [(turtle 0) (turtle 1) (turtle 2)]

nw:weighted-path-to

nw:weighted-path-totarget-turtleweight-variable

Likenw:path-to,buttakeslinkweightintoaccount.

Example:

links-own [ weight ]to go clear-all create-turtles 5 ask turtle 0 [ create-link-with turtle 1 [ set weight 2.0 ] ] ask turtle 1 [ create-link-with turtle 2 [ set weight 2.0 ] ] ask turtle 0 [ create-link-with turtle 3 [ set weight 0.5 ] ] ask turtle 3 [ create-link-with turtle 4 [ set weight 0.5 ] ] ask turtle 4 [ create-link-with turtle 2 [ set weight 0.5 ] ] ask turtle 0 [ show nw:weighted-path-to turtle 2 weight ]end

Willoutput:

(turtle 0): [(link 0 3) (link 3 4) (link 2 4)]

nw:turtles-on-weighted-path-to

nw:turtles-on-weighted-path-totarget-turtleweight-variable

Likenw:turtles-on-path-to,buttakeslinkweightintoaccount.

Example:

links-own [ weight ]to go clear-all create-turtles 5 ask turtle 0 [ create-link-with turtle 1 [ set weight 2.0 ] ] ask turtle 1 [ create-link-with turtle 2 [ set weight 2.0 ] ] ask turtle 0 [ create-link-with turtle 3 [ set weight 0.5 ] ] ask turtle 3 [ create-link-with turtle 4 [ set weight 0.5 ] ] ask turtle 4 [ create-link-with turtle 2 [ set weight 0.5 ] ] ask turtle 0 [ show nw:weighted-path-to turtle 2 weight ]end

Willoutput:

(turtle 0): [(turtle 0) (turtle 3) (turtle 4) (turtle 2)]

nw:mean-path-length

nw:mean-path-length

Reportstheaverageshortest-pathlengthbetweenalldistinctpairsofnodesinthecurrentcontext.

Reportsfalseunlesspathsexistbetweenallpairs.

Example:

links-own [ weight ]to go clear-all create-turtles 3 ask turtle 0 [ create-link-with turtle 1 [ set weight 2.0 ] ] ask turtle 1 [ create-link-with turtle 2 [ set weight 2.0 ] ] show nw:mean-path-length create-turtles 1 ; create a new, disconnected turtle show nw:mean-path-lengthend

Willouput:

observer: 1.3333333333333333observer: false

nw:mean-weighted-path-length

nw:mean-weighted-path-lengthweight-variable

Likenw:mean-path-length,buttakesintoaccountlinkweights.

Example:

links-own [ weight ]to go clear-all create-turtles 3 ask turtle 0 [ create-link-with turtle 1 [ set weight 2.0 ] ] ask turtle 1 [ create-link-with turtle 2 [ set weight 2.0 ] ] show nw:mean-path-length show nw:mean-weighted-path-length weight create-turtles 1 ; create a new, disconnected turtle show nw:mean-path-length show nw:mean-weighted-path-length weightend

Willouput:

observer: 2.6666666666666665observer: false

nw:betweenness-centrality

nw:betweenness-centrality

Tocalculatethebetweennesscentralityofaturtle,youtakeeveryotherpossiblepairsofturtlesand,foreachpair,youcalculatetheproportionofshortestpathsbetweenmembersofthepairthatpassesthroughthecurrentturtle.Thebetweennesscentralityofaturtleisthesumofthese.

Asofnow,linkweightsarenottakenintoaccount.

nw:eigenvector-centrality

nw:eigenvector-centrality

TheEigenvectorcentralityofanodecanbethoughtofastheamountofinfluenceanodehasonanetwork.Inpractice,turtlesthatareconnectedtoalotofotherturtlesthatarethemselveswell-connected(andsoon)getahigherEigenvectorcentralityscore.

Inthisimplementation,theeigenvectorcentralityisnormalizedsuchthatthehighesteigenvectorcentralityanodecanhaveis1.ThisimplementationisdesignedtoagreewithGephi’simplementationouttoatleast3decimalplaces.IfyoudiscoverthatitdisagreeswithGephionaparticularnetwork,pleasereportit.

Theprimitiverespectslinkdirection,eveninmixed-directednetworks.ThisistheoneplacewhereitshoulddisagreewithGephi;Gephirefusestotreatdirectedlinksasdirectedinmixed-networks.


nw:page-rank

nw:page-rank

Thepagerankofanodecanbethoughtofastheproportionoftimethatanagentwalkingforeveratrandomonthenetworkwouldspendatthisnode.Theagenthasanequalchanceoftakinganyofanodesedges,andwilljumparoundthenetworkcompletelyrandomly15%ofthetime.Inpractice,likewitheigenvectorcentrality,turtlesthatareconnectedtoalotofotherturtlesthatarethemselveswell-connected(andsoon)getahigherpagerank.

Pagerankisoneoftheseveralalgorithmsthatsearchenginesusetodeterminetheimportanceofawebsite.

Thesumofallpagerankvaluesshouldbeapproximatelyone.Unlikeeigenvectorcentrality,pagerankisdefinedforallnetworks,nomattertheconnectivity.Currently,ittreatsalllinksasundirectedlinks.


nw:closeness-centrality

nw:closeness-centrality

Theclosenesscentralityofaturtleisdefinedastheinverseoftheaverageofit’sdistancestoallotherturtles.(Somepeopleusethesumofdistancesinsteadoftheaverage,buttheextensionusestheaverage.)

Notethatthisprimitivereportstheintra-componentclosenessofaturtle,thatis,ittakesintoaccountonlythedistancestotheturtlesthatarepartofthesamecomponentasthecurrentturtle,sincedistancetoturtlesinothercomponentsisundefined.Theclosenesscentralityofanisolatedturtleisdefinedtobezero.

nw:weighted-closeness-centrality

nw:weighted-closeness-centralitylink-weight-variable

Thisisidenticaltonw:closeness-centrality,exceptthatweightsprovidedbythegivenvariablearetreatedasthedistancesoflinks.

nw:clustering-coefficient

nw:clustering-coefficient

Reportsthelocalclusteringcoefficientoftheturtle.Theclusteringcoefficientofanodemeasureshowconnecteditsneighborsare.Itisdefinedasthenumberoflinksbetweenthenode’sneighborsdividedbythetotalnumberofpossiblelinksbetweenitsneighbors.

http://en.wikipedia.org/wiki/Betweenness_centrality

http://en.wikipedia.org/wiki/Centrality#Eigenvector_centrality

https://github.com/NetLogo/NW-Extension/issues/new

https://en.wikipedia.org/wiki/PageRank

http://en.wikipedia.org/wiki/Centrality#Closeness_centrality

http://en.wikipedia.org/wiki/Connected_component_%28graph_theory%29

http://en.wikipedia.org/wiki/Clustering_coefficient#Local_clustering_coefficient

nw:clustering-coefficienttakesthedirectednessoflinksintoaccount.Adirectedlinkcountsasasinglelinkwhereasanundirectedlinkcountsastwolinks(onegoingone-way,onegoingtheother).

Theglobalclusteringcoefficientmeasureshowmuchnodestendtoclustertogetherinthenetworkingeneral.Itisdefinedbasedonthetypesoftripletsinthenetwork.Atripletconsistsofacentralnodeandtwoofitsneighbors.Ifitsneighborsarealsoconnected,it’saclosedtriplet.Ifitsneighborsarenotconnected,it’sanopentriplet.Theglobalclusteringcoefficientissimplythenumberofclosedtripletsinanetworkdividedbythetotalnumberoftriplets.Itcanbecalculatedfromthelocalclusteringcoefficientquiteeasilywiththefollowingcode

to-report global-clustering-coefficient let closed-triplets sum [ nw:clustering-coefficient * count my-links * (count my-links - 1) ] of turtles let triplets sum [ count my-links * (count my-links - 1) ] of turtles report closed-triplets / tripletsend

Notethattheabovewillonlyworkwiththedefaultcontext,andmayneedtotweakedifyou’vesettheturtlesorlinksinthenetworktosomethingotherthanturtlesandlinks.

Theaveragelocalclusteringcoefficientisanotherpopularmethodformeasuringtheamountofclusteringinthenetworkasawhole.Itmaybecalculatedwith

mean [ nw:clustering-coefficient ] of turtles

nw:modularity

nw:modularity

Modularityisameasurementofcommunitystructureinthenetwork.Itisdefinedbasedonthenumberofin-communitylinksversusthenumberofbetween-communitylinks.Thisprimitivetakesasinputalistofagentsets,whereeachoftheagentsetsisonethecommunitiesthatyou’reseparatingthenetworkinto.

Thismeasurementworksonundirected,directed,andmixed-directednessnetworks.Inthecaseofmixed-directedness,undirectedlinksaretreatedessentiallythesameastwoopposingdirectedlinks.Itdoesnottakeweightintoaccount.

Example:

nw:modularity (list (turtles with [ color = blue ]) (turtles with [ color = red ]))

nw:bicomponent-clusters

nw:bicomponent-clusters

Reportsthelistofbicomponentclustersinthecurrentnetworkcontext.Abicomponent(alsoknownasamaximalbiconnectedsubgraph)isapartofanetworkthatcannotbedisconnectedbyremovingonlyonenode(i.e.youneedtoremoveatleasttwotodisconnectit).Theresultisreportedasalistofagentsets,inrandomorder.Notethatoneturtlecanbeamemberofmorethanonebicomponentatonce.

nw:weak-component-clusters

nw:weak-component-clusters

Reportsthelistof“weakly”connectedcomponentsinthecurrentnetworkcontext.Aweaklyconnectedcomponentissimplyagroupofnodeswherethereisapathfromeachnodetoeveryothernode.A“strongly”connectedcomponentwouldbeonewherethereisadirectedpathfromeachnodetoeveryother.Theextensiondoesnotsupporttheidentificationofstronglyconnectedcomponentsatthemoment.

Theresultisreportedasalistofagentsets,inrandomorder.Notethatoneturtlecannotbeamemberofmorethanoneweaklyconnectedcomponentatonce.

nw:louvain-communities

nw:louvain-communities

Detectscommunitystructurepresentinthenetwork.ItdoesthisbymaximizingmodularityusingtheLouvainmethod.Thecommunitiesarereportedasalistofturtle-sets.

http://en.wikipedia.org/wiki/Clustering_coefficient#Global_clustering_coefficient

https://en.wikipedia.org/wiki/Modularity_(networks)

http://en.wikipedia.org/wiki/Biconnected_component

http://en.wikipedia.org/wiki/Connected_component_%28graph_theory%29

https://en.wikipedia.org/wiki/Louvain_Modularity

Oftenyou’llwanttotellturtlesaboutthecommunitythattheyarein.Youcandothislikeso:

turtles-own [ community ]

...

foreach ls:louvain-communities [ [comm] -> ask comm [ set community comm ]]

Youcangiveeachcommunityitsowncolorwithsomethinglikethis:

let communities ls:louvain-communitieslet colors sublist 0 (length communities) base-colors(foreach communities colors [ [community col] -> ask community [ set color col ]])

nw:maximal-cliques

nw:maximal-cliques

Acliqueisasubsetofanetworkinwhicheverynodehasadirectlinktoeveryothernode.Amaximalcliqueisacliquethatisnot,itself,containedinabiggerclique.

Theresultisreportedasalistofagentsets,inrandomorder.Notethatoneturtlecanbeamemberofmorethanonemaximalcliqueatonce.

TheprimitiveusestheBron–Kerboschalgorithmandonlyworkswithundirectedlinks.

nw:biggest-maximal-cliques

nw:biggest-maximal-cliques

Thebiggestmaximalcliquesare,asthenameimplies,thebiggestcliquesinthecurrentcontext.Often,morethanonecliquearetiedforthetitleofbiggestclique,sotheresultisreportedasalistofagentsets,inrandomorder.Ifyouwantonlyoneclique,useone-of nw:biggest-maximal-cliques.

TheprimitiveusestheBron–Kerboschalgorithmandonlyworkswithundirectedlinks.

nw:generate-preferential-attachment

nw:generate-preferential-attachmentturtle-breedlink-breednum-nodesoptional-command-block

GeneratesanewnetworkusingtheBarabási–Albertalgorithm.Thisnetworkwillhavethepropertyofbeing“scalefree”:thedistributionofdegrees(i.e.thenumberoflinksforeachturtle)shouldfollowapowerlaw.

Inthisversionoftheprimitive,turtlesareadded,onebyone,eachformingonelinktoapreviouslyaddedturtle,untilnum-nodesisreached.Themorelinksaturtlealreadyhas,thegreatertheprobabilitythatnewturtlesformlinkswithitwhentheyareadded.Futureversionsoftheprimitivemightprovidemoreflexibilityinthewaythenetworkisgenerated.

Ifyouspecifyanoptional-command-block,itisexecutedforeachturtleinthenewlycreatednetwork.Forexample:

nw:generate-preferential-attachment turtles links 100 [ set color red ]

nw:generate-random

nw:generate-randomturtle-breedlink-breednum-nodesconnection-probabilityoptional-command-block

Generatesanewrandomnetworkofnum-nodesturtlesinwhicheachonehasaconnection-probability(between0and1)ofbeingconnectedtoeachotherturtles.ThealgorithmusestheG(n,p)variantoftheErdős–Rényimodel.

ThealgorithmisO(n²)fordirectednetworksandO(n²/2)forundirectednetworks,sogeneratingmorethanacouplethousandnodeswilllikelytakeaverylongtime.


http://en.wikipedia.org/wiki/Clique_%28graph_theory%29

http://en.wikipedia.org/wiki/Bron%E2%80%93Kerbosch_algorithm

http://en.wikipedia.org/wiki/Clique_%28graph_theory%29

http://en.wikipedia.org/wiki/Bron%E2%80%93Kerbosch_algorithm

http://en.wikipedia.org/wiki/Barab%C3%A1si%E2%80%93Albert_model

http://en.wikipedia.org/wiki/Erd%C5%91s%E2%80%93R%C3%A9nyi_model

nw:generate-random turtles links 100 0.5 [ set color red ]

nw:generate-watts-strogatz

nw:generate-watts-strogatzturtle-breedlink-breednum-nodesneighborhood-sizerewire-probabilityoptional-command-block

GeneratesanewWatts-Strogatzsmall-worldnetwork.

Thealgorithmbeginsbycreatingaringofnodes,whereeachnodeisconnectedtoneighborhood-sizenodesoneitherside.Then,eachlinkisrewiredwithprobabilityrewire-prob.

Ifyouspecifyanoptional-command-block,itisexecutedforeachturtleinthenewlycreatednetwork.Furthermore,theturtlesaregeneratedintheordertheyappearasincreate-ordered-turtles.So,inordertolaytheringoutasaring,youcandosomethinglike:

nw:generate-watts-strogatz turtles links 50 2 0.1 [ fd 10 ]

nw:generate-small-world

nw:generate-small-worldturtle-breedlink-breedrow-countcolumn-countclustering-exponentis-toroidaloptional-command-block

Generatesanewsmall-worldnetworkusingtheKleinbergModel.Notethatnw:generate-watts-strogatzgeneratesamoretraditionalsmall-worldnetwork.

Thealgorithmproceedsbygeneratingalatticeofthegivennumberofrowsandcolumns(thelatticewillwraparounditselfifis-toroidalistrue).The“smallworldeffect”iscreatedbyaddingadditionallinksbetweenthenodesinthelattice.Thehighertheclustering-exponent,themorethealgorithmwillfavoralreadyclose-bynodeswhenaddingnewlinks.Aclusteringexponentof2.0istypicallyused.


nw:generate-small-world turtles links 10 10 2.0 false [ set color red ]

Theturtlesaregeneratedintheorderthattheyappearinthelattice.So,forinstance,togenerateakleinberglatticeaccrosstheentireworld,andlayitoutaccordingly,trythefollowing:

nw:generate-small-world turtles links world-width world-height 2.0 false(foreach (sort turtles) (sort patches) [ [t p] -> ask t [ move-to p ] ])

nw:generate-lattice-2d

nw:generate-lattice-2dturtle-breedlink-breedrow-countcolumn-countis-toroidaloptional-command-block

Generatesanew2Dlatticenetwork(basically,agrid)ofrow-countrowsandcolumn-countcolumns.Thegridwillwraparounditselfifis-toroidalistrue.


nw:generate-lattice-2d turtles links 10 10 false [ set color red ]

Theturtlesaregeneratedintheorderthattheyappearinthelattice.So,forinstance,togeneratealatticeaccrosstheentireworld,andlayitoutaccordingly,trythefollowing:

nw:generate-lattice-2d turtles links world-width world-height false(foreach (sort turtles) (sort patches) [ [t p] -> ask t [ move-to p ] ])

nw:generate-ring

nw:generate-ringturtle-breedlink-breednum-nodesoptional-command-block

Generatesaringnetworkofnum-nodesturtles,inwhicheachturtleisconnectedtoexactlytwootherturtles.

https://en.wikipedia.org/wiki/Watts_and_Strogatz_model

http://en.wikipedia.org/wiki/Small-world_network

http://en.wikipedia.org/wiki/Small_world_routing#The_Kleinberg_Model

http://en.wikipedia.org/wiki/Lattice_graph

http://en.wikipedia.org/wiki/Ring_network

Thenumberofnodesmustbeatleastthree.


nw:generate-ring turtles links 100 [ set color red ]

nw:generate-star

nw:generate-starturtle-breedlink-breednum-nodesoptional-command-block

Generatesastarnetworkinwhichthereisonecentralturtleandeveryotherturtleisconnectedonlytothiscentralnode.Thenumberofturtlescanbeaslowasone,butitwon’tlookmuchlikeastar.


nw:generate-star turtles links 100 [ set color red ]

nw:generate-wheel

nw:generate-wheelturtle-breedlink-breednum-nodesoptional-command-block

Variants:

nw:generate-wheel-inwardnw:generate-wheel-outward

Generatesawheelnetwork,whichisbasicallyaringnetworkwithanadditional“central”turtlethatisconnectedtoeveryotherturtle.

Thenumberofnodesmustbeatleastfour.

Thenw:generate-wheelonlyworkswithundirectedlinkbreeds.Thenw:generate-wheel-inwardandnw:generate-wheel-outwardversionsonlyworkwithdirectedlink-breed.Theinwardandoutwardpartoftheprimitivenamesrefertothedirectionthatthe“spokes”ofthewheelpointtorelativetothecentralturtle.


nw:generate-wheel turtles links 100 [ set color red ]

nw:save-matrix

nw:save-matrixfile-name

Savesthecurrentnetwork,asdefinedbynw:set-context,tofile-name,asatextfile,intheformofasimpleconnectionmatrix.

Hereis,forexample,aundirectedringnetworkwithfournodes:

0.00 1.00 0.00 1.001.00 0.00 1.00 0.000.00 1.00 0.00 1.001.00 0.00 1.00 0.00

Andhereisthedirectedversion:

0.00 1.00 0.00 0.000.00 0.00 1.00 0.000.00 0.00 0.00 1.001.00 0.00 0.00 0.00

Atthemoment,nw:save-matrixdoesnotsupportlinkweights.Everylinkisrepresentedasa“1.00”intheconnectionmatrix.Thiswillchangeinafutureversionoftheextension.

nw:load-matrix

nw:load-matrixfile-nameoptional-command-block

http://en.wikipedia.org/wiki/Star_graph

http://en.wikipedia.org/wiki/Wheel_graph

http://en.wikipedia.org/wiki/Ring_network

Generatesanewnetworkaccordingtotheconnectionmatrixsavedinfile-name,usingturtle-breedandlink-breedtocreatethenewturtlesandlinks.

Atthemoment,nw:load-matrixdoesnotsupportlinkweights.

Pleasebeawarethatthebreedsthatuseusetoloadthematrixmaybedifferentfromthosethatyouusedwhenyousavedit.

Forexample:

extensions [ nw ]directed-link-breed [ dirlinks dirlink ]to go clear-all crt 5 [ create-dirlinks-to other turtles ] nw:set-context turtles dirlinks nw:save-matrix "matrix.txt" clear-all nw:load-matrix "matrix.txt" turtles links layout-circle turtles 10end

…willgiveyoubackundirectedlinks,evenifyousaveddirectedlinksintothematrix.


nw:load-matrix "matrix.txt" turtles links [ set color red ]

nw:save-graphml

nw:save-graphmlfile-name

YoucansavethecurrentgraphtoGraphML.ThefollowingNetLogocode:

extensions [ nw ]

breed [ bankers banker ]bankers-own [ bank-name ]breed [ clients client ]clients-own [ hometown ]

undirected-link-breed [ friendships friendship ]

directed-link-breed [ accounts account ]accounts-own [ amount ]

to go clear-all create-bankers 1 [ set bank-name "The Bank" ] create-clients 1 [ set hometown "Turtle City" create-friendship-with banker 0 create-account-to banker 0 [ set amount 9999.99 ] ] nw:set-context turtles links nw:save-graphml "example.graphml"end

WillproducethefollowingGraphMLfile:

<?xml version="1.0" encoding="UTF-8"?><graphml xmlns="http://graphml.graphdrawing.org/xmlns/graphml"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://graphml.graphdrawing.org/xmlns/graphml"><key id="PEN-MODE" for="node" attr.name="PEN-MODE" attr.type="string"/><key id="YCOR" for="node" attr.name="YCOR" attr.type="double"/><key id="PEN-SIZE" for="node" attr.name="PEN-SIZE" attr.type="double"/><key id="LABEL" for="node" attr.name="LABEL" attr.type="string"/><key id="SHAPE" for="node" attr.name="SHAPE" attr.type="string"/><key id="BREED" for="node" attr.name="BREED" attr.type="string"/><key id="WHO" for="node" attr.name="WHO" attr.type="double"/><key id="HIDDEN?" for="node" attr.name="HIDDEN?" attr.type="boolean"/><key id="LABEL-COLOR" for="node" attr.name="LABEL-COLOR" attr.type="double"/><key id="HEADING" for="node" attr.name="HEADING" attr.type="double"/><key id="BANK-NAME" for="node" attr.name="BANK-NAME" attr.type="string"/><key id="HOMETOWN" for="node" attr.name="HOMETOWN" attr.type="string"/><key id="COLOR" for="node" attr.name="COLOR" attr.type="double"/><key id="XCOR" for="node" attr.name="XCOR" attr.type="double"/>

<key id="SIZE" for="node" attr.name="SIZE" attr.type="double"/><key id="END1" for="edge" attr.name="END1" attr.type="string"/><key id="TIE-MODE" for="edge" attr.name="TIE-MODE" attr.type="string"/><key id="END2" for="edge" attr.name="END2" attr.type="string"/><key id="LABEL-COLOR" for="edge" attr.name="LABEL-COLOR" attr.type="double"/><key id="THICKNESS" for="edge" attr.name="THICKNESS" attr.type="double"/><key id="LABEL" for="edge" attr.name="LABEL" attr.type="string"/><key id="SHAPE" for="edge" attr.name="SHAPE" attr.type="string"/><key id="BREED" for="edge" attr.name="BREED" attr.type="string"/><key id="COLOR" for="edge" attr.name="COLOR" attr.type="double"/><key id="AMOUNT" for="edge" attr.name="AMOUNT" attr.type="double"/><key id="HIDDEN?" for="edge" attr.name="HIDDEN?" attr.type="boolean"/><graph edgedefault="undirected"><node id="client 1"><data key="PEN-MODE">up</data><data key="YCOR">0</data><data key="PEN-SIZE">1</data><data key="LABEL"></data><data key="SHAPE">default</data><data key="BREED">clients</data><data key="WHO">1</data><data key="HIDDEN?">false</data><data key="LABEL-COLOR">9.9</data><data key="HEADING">356</data><data key="HOMETOWN">Turtle City</data><data key="COLOR">115</data><data key="XCOR">0</data><data key="SIZE">1</data></node><node id="banker 0"><data key="PEN-MODE">up</data><data key="YCOR">0</data><data key="PEN-SIZE">1</data><data key="LABEL"></data><data key="SHAPE">default</data><data key="BREED">bankers</data><data key="WHO">0</data><data key="HIDDEN?">false</data><data key="LABEL-COLOR">9.9</data><data key="HEADING">32</data><data key="BANK-NAME">The Bank</data><data key="COLOR">85</data><data key="XCOR">0</data><data key="SIZE">1</data></node><edge source="client 1" target="banker 0"><data key="END1">(client 1)</data><data key="TIE-MODE">none</data><data key="END2">(banker 0)</data><data key="LABEL-COLOR">9.9</data><data key="THICKNESS">0</data><data key="LABEL"></data><data key="SHAPE">default</data><data key="BREED">accounts</data><data key="COLOR">5</data><data key="AMOUNT">9999.99</data><data key="HIDDEN?">false</data></edge><edge source="banker 0" target="client 1"><data key="END1">(banker 0)</data><data key="TIE-MODE">none</data><data key="END2">(client 1)</data><data key="LABEL-COLOR">9.9</data><data key="THICKNESS">0</data><data key="LABEL"></data><data key="SHAPE">default</data><data key="BREED">friendships</data><data key="COLOR">5</data><data key="HIDDEN?">false</data></edge></graph></graphml>

Afewthingstonotice:

Thebreedisstoredasdatafield,bothfornodesandedges.ThedataincludesbothNetLogo’sinternalvariablesandthevariablesthatweredefinedaseitherbreeds-own,turtles-own,linkbreeds-ownorlinks-own.Eachkeygetsanattr.typebasedontheactualtypesofthevaluescontainedintheagentvariables.Thethreepossibletypesare"string","double"and"boolean".Todeterminetheattributetypeofaparticularagentvariable,theextensionwilllookatthefirstagentinthegraph.Toseewhichagentisfirst,youcanlookattheresultofnw:get-context.Notethatvariablescontainingothertypesofvalues,suchasturtles,patches,lists,etc.,willbestoredasstrings.Thisexampleonlyhasadirectedlink,andyouwillnoticethe<graph edgedefault="directed">element.Ifwehadonlyundirectedlinks,wewouldhave<graph edgedefault="undirected">.Whatifwetrytomixbothkindsoflink?Atthemoment,theextensionwillsavesucha“mixed”graphasifitwereanundirectedgraph(seethisissueformoredetails).Theorderofthesourceandtargetwillberespected,however,soifyouknowwhichbreedsrepresentdirectedlinks,youcanfigureitoutaposteriori.

nw:load-graphml

https://github.com/NetLogo/NW-Extension/issues/58

nw:load-graphmlfile-nameoptional-command-block

LoadingaGraphMLfileintoNetLogowiththenetworkextensionshouldbeassimpleascallingnw:load-graphml"example.graphml",butthereisabitofpreparationinvolved.

Thekeyideaisthatnw:load-graphmlwilltrytoassigntheattributevaluesdefinedintheGraphMLfiletoNetLogoagentvariablesofthesamenames(thisisnotcasesensitive).Thefirstoneittriestosetisbreedifitisthere,sotheturtleorlinkwillgettherightbreedand,hence,therightbreedvariables.

Onespecialcaseisthewhonumber,whichisignoredbytheimporterifitispresentasaGraphMLattribute:NetLogodoesnotallowyoutomodifythisnumberonceaturtleiscreatedand,besides,therecouldalreadybeanexistingturtlewiththatnumber.

ThesimplestcasetohandleiswhentheoriginalGraphMLfilehasbeensavedfromNetLogobyusingnw:save-graphml.Inthiscase,allyoushouldhavetodoistomakesurethatyouhavethesamebreedandvariablesdefinitionaswhenyousavedthefileandyoushouldgetbackyouroriginalgraph.Forexample,ifyouwanttoloadthefilefromthenw:save-graphmlexampleabove,youshouldhavethefollowingdefinitions:

breed [ bankers banker ]bankers-own [ bank-name ]breed [ clients client ]clients-own [ hometown ]

undirected-link-breed [ friendships friendship ]

directed-link-breed [ accounts account ]accounts-own [ amount ]

LoadingagraphthatwassavedfromadifferentprogramthanNetLogoisquitepossibleaswell,butitmaytakeabitoftinkeringtogetalltheattribute-variablematchupright.Ifyouencountermajorproblems,pleasedonothesitatetoopenanissue.

Theextensionwilltrytoassignthetypedefinedbyattr.typetoeachvariablethatitloads.Ifit’sunabletoconvertittothattype,itwillloaditasastring.Ifattr.typeisnotdefined,orissettoanunknownvalue,theextensionwillfirsttrytoloadthevalueasadouble,thentryitasaboolean,andfinallyfallbackonastring.


nw:load-graphml "example.graphml" [ set color red ]

Notethatthiscommandblockcanbeusedtobuildalistoranagentsetcontainingthenewlycreatednodes:

let node-list []nw:load-graphml "example.graphml" [ set node-list lput self node-list]let node-set turtle-set node-list

nw:load

nw:loadfile-namedefault-turtle-breeddefault-link-breedoptional-command-block

Filetypespecificvariants:

nw:loadnw:load-dlnw:load-gdfnw:load-gexfnw:load-gmlnw:load-vna

ImportthegivenfileintoNetLogo.Likenw:load-graphml,theimporterwilldoitsbesttomatchnodeandedgeattributesinthefilewithturtleandlinkvariablesinNetLogo.IfbreedisspecifiedfornodesandedgesinthefileandexistsinNetLogo,itwillbeused.Otherwise,thedefaultturtleandlinkbreedsareused.

Limitations:

Multigraphsarenotsupportedinimporting.Evenifthefileformatsupportsit(andmanydon’t),onlythefirstlinkwillbeusedonimport.ThisisduetoalimitationintheparsinglibrariesNWuses.nw:load-graphmldoessupportmultigraphswiththenormalNetLogolimitationthattwoturtlescansharemorethanonelinkonlyifallthelinksareofdifferentbreeds.

https://github.com/NetLogo/NW-Extension/issues/new

nw:loaddeterminesthefile-typeofgivenfilebasedontheextensionandcallsthecorrespondingload-*primitiveonit.NotethatGraphMLmustbeimportedwithnw:load-graphml.

nw:save

nw:savefile-name

Filetypespecificvariants:

nw:save-dlnw:save-gdfnw:save-gexfnw:save-gmlnw:save-vna

Exportthenetworkcontextinthegivenformattothegivenfile.Turtleandlinkattributeswillbeexportedtoformatsthatsupportnodeandedgeproperties.

Limitations:

xandy(notxcorandycor)canonlybenumbers.xandyarecommonlyusedinformatspertainingtopositionandbehindthescenesNWusesGephi’slibrariesforexporting.Furthermore,xandywillbeaddedeveniftheydidn’texistinthemodel.Again,thisisbecauseNWusesGephi’slibrarieswhichassumethatnodeshavepositionsstoredinxandy.IfyouwishtoexporttoGephispecifically,werecommendcreatingxandyturtlesvariablesandsettingthemtoxcorandycorbeforeexport.ColorwillbeexportedinastandardRGBformat.Thisshouldhopefullyincreasecompatibilitywithotherprograms.Turtleandlinkvariablesthatcontainvaluesofdifferenttypeswillbestoredasstrings.Unfortunately,mostnetworkformatsrequirethatnodeandattributeshaveasingletype.Manyprogramsuselabeltostoretheidofnodes.Thus,ifyou’rehavingtroubleimportingdataexportedfromNetLogointoanotherprogram,youmighttrysettingturtles’labelstotheirwhonumber.Multigraphsarenotsupported.Thus,twoturtlescanshareatmostonelink.nw:save-graphmldoessupportmultigraphs,sousethatifturtlescanhavemorethanonetypeoflinkconnectingthem.

nw:savedeterminesthefile-typeofthegivenfilebasedontheextensionandcallsthecorrespondingsave-*primitiveonit.NotethatGraphMLmustbeexportedwithnw:save-graphml.

NetLogoPaletteExtension

UsingthePaletteExtension

TheNetLogopaletteextensionallowstomapvaluestocolors.ThecolorsgobeyondNetLogocolors,includingColorBrewercolorschemesorarbitraryRGBcolors.Additionally,itprovidesaprimitivetomaptocolorgradientsandaprimitivetolaunchaColorBrewerdialogforeasyschemeselection.

GettingStarted

TogetstartedwithpalettesaddtothetopofyourCodetab:

extensions [palette]

youcanthencallanyoftheprimitivesbyaddingpalette:beforetheprimitive:

palette:scale-gradientpalette:scale-scheme

palette:scheme-colorpalette:scheme-dialog

ThepaletteextensionprimitivesreturnalistcontainingRGBcolors[[r g b][r g b]...[r g b]] ,exceptforpalette:scheme-dialogwhichopensadialog.

WhatcolorsshouldIuse?

ColorBrewerhasmanycolorswheretostart.ColorBrewerhasthreeschemesSequential,DivergentandQualitative.TheuseofColorBrewerformapsisdiscussedatlengthinthispaper(Harrower,Brewer2003).Choosingtherightcolorsisadesignproblem,thus,therearemanyacceptablesolution.However,theseguidelinesmightbeusefulforchoosingcolorsinAgentBasedModels:

Sequentialcolorsarebestforcontinuousnaturalphenomenamodelssuchasasheatdiffusioninphysicsorfireinearthsciences.Divergentcolorsareusefulforhighlightingamiddlevalueinamodel.Itcanbealsoappliedtotheheatdiffusionmodelifthegoalistohighlightthemiddletemperature.Qualitativecolorsarebestforchoosingcolorsinmodelswherecolordenotescategoryandnotvalue.Foragentsthatcoverlargeareasavoidstrongcolorsandtrytousepastelcolors.However,foralownumberofsmallisolatedagentstrytousestrongcolorssuchassuchaaccent.Themaingoalistoavoidhavingalargeareacoveredwithagentswithabrightcolorandorhavingsmallareashavingamutedpastelcolor.Ifyouarecoloringbothturtlesandpatches,makesuretheyhavedifferentrangesofhue,saturationandvalue.E.g.Usedifferenthuesofpastelforpatchesandaccentforturtles

ShouldIuseacontinuouscolorgradientorjustadiscretecolorset?

Theanswerdependsonthetaskthatyourwillbeaskingfromyouruser.

Forexample,gradientsaremoreaestheticthusaremorememorablethandiscretecolors.Consequently,agradientcanbeabetterchoiceforpresentationswherethemaingoaloftheimageistobeattractiveandmemorable.However,binningvaluesinadiscretesetofcolorssimplifiestaskssuchasestimationandcountingbyremovingunnecessarydetailtodisplaythebigpicture.Thus,discretecolorscanbeabetterchoiceforapaperwheretheuserwillhavethetimeandinteresttostudythevisualization.

InordertoseethedifferenceyoucanturnonandoffthegradientintheHeatDiffusionmodel.Youcanobservethatturninggradientonmakesthemodelmoreaesthetic,butitbecomeshardertoestimatethevalueofapatchatagivenposition.

ExampleModels

ThereisanexampleofusingthepaletteprimitivesintheCodeExamplessectionofthemodelslibrary:

PaletteExample

AndoneSampleModelthatusestheextension:

HeatDiffusion-AlternativeGradient

FurtherReading

BesuretochecktheColorBrewerwebpageTogetadeeperunderstandingofhowtousethecolorschemesreadtheColorBrewerpaper(Harrower,Brewer2003)

Primitives

palette:scale-gradientpalette:scale-schemepalette:scheme-colorspalette:scale-gradient

palette:scale-gradient

palette:scale-gradientrgb-color-listnumberrange1range2

ReportsanRGBcolorproportionaltonumberusingagradientgeneratedwithrgb-color-list.Anrgb-color-listconsistofalistcontainingRGBlistwiththreevaluesbetween0and255:[[r1g1b1][r2g2b2][r3g3b3]…]

Ifrange1islessthanrange2,thecolorwillbedirectlymappedtogradientcolors.While,ifrange2islessthanrange1,thecolorgradientisinverted.

Ifnumberislessthanrange1,thenthefirstcolorofisRGB-color-listischosen.

Ifnumberisgraterthanrange2,thenthelastcolorofisRGB-color-listischosen.

Example:

ask patches[ set pcolor palette:scale-gradient [[255 0 0] [0 0 255]] pxcor min-pxcor max-pxcor]

;; colors each patch with a color proportional to the gradient

palette:scale-scheme

palette:scale-schemescheme-typescheme-colornumber-of-classesrange1range2

ReportsanRGBcolorproportionaltonumberusingthecolorbrewerschemes.IttakessixargumentsthefirstthreeargumentsdefinetheColorBrewerlegend.Firtheusershouldselectascheme-typewhichcanbe“Sequential”,“Divergent,Qualitative”.Thenitshouldselectavarietyofscheme-colorswhichdependingonthescheme-colorcanhavenamessuchas“Reds”,“Divergent”,“Set1”.Finallytheusershouldselectthenumberofclasseswithaminimumof3andamaximumbetween9and11.Formoreinformationgotohttp://www.colorbrewer.orgorconsultthescheme-dialogprimitive.

Ifrange1islessthanrange2,thecolorwillbedirectlymappedtoschemecolors.While,ifrange2islessthanrange1,thecolorschemeselectionisinverted.

Ifnumberislessthanrange1,thenthefirstcoloroftheresultingColorBrewerlegendischosen.

Ifnumberisgraterthanrange2,thenthelastcoloroftheresultingColorBrewerlegendischosen.

Example:

ask patches[ set pcolor palette:scale-scheme [[255 0 0] [0 0 255]] pxcor min-pxcor max-pxcor]

;; colors each patch with a color from the Color Brewer Schemes

palette:scheme-colors

palette:scheme-colorsscheme-typescheme-colornumber-of-classes

reportalistofRGBcolorswiththesizespecifiedintheanumberofclasses

Example:

show palette:scheme-colors "Divergent" "Spectral" 3=> [[252 141 89] [255 255 191] [153 213 148]]

; The schemes-color primitive can be used with the scale-gradient primitiveask patches [set pcolor palette:scale-gradient palette:scheme-colors "Divergent" "Spectral" 9 pxcor min-pxcor max-pxcor]

http://colorbrewer2.org/

http://www.colorbrewer.org

palette:scale-gradient

palette:scale-gradientrgb-color-listnumberrange1range2

ReportsanRGBcolorproportionaltonumberusingagradientgeneratedwithrgb-color-list.Anrgb-color-listconsistofalistcontainingRGBlistwiththreevaluesbetween0and255:[[r1g1b1][r2g2b2][r3g3b3]…]

Ifrange1islessthanrange2,thecolorwillbedirectlymappedtogradientcolors.While,ifrange2islessthanrange1,thecolorgradientisinverted.

Ifnumberislessthanrange1,thenthefirstcolorofisRGB-color-listischosen.

Ifnumberisgraterthanrange2,thenthelastcolorofisRGB-color-listischosen.

Example:

ask patches[ set pcolor palette:scale-gradient [[255 0 0] [0 0 255]] pxcor min-pxcor max-pxcor]

;; colors each patch with a color proportional to the gradient

References

ColorBrewerwww.colorbrewer.org

HARROWER,M.andC.BREWER(2003).ColorBrewer:Anonlinetoolforselectingcolorschemesformaps.TheCartographicJournal40(1):27-37.)

HEALEY,CG(2006)PerceptioninVisualization,(comprehensivereviewupdatedregularly).

HEALEY,CG,BOOTHKS,andENNS,JT(1995).VisualizingReal-TimeMultivariateDataUsingPreattentiveProcessingACMTransactionsonModelingandComputerSimulation5,3,190-221.

TUFTE,E(1983)TheVisualDisplayofQuantitativeInformation,GraphicsPress.

WARE,C(2004)InformationVisualization,2ndEd.,MorganKaufmann.Feedback

http://www.colorbrewer.org

NetLogoProfilerExtension

UsingtheProfilerExtension

Ifyou’dlikeyourmodeltorunfaster,theprofilerextensionmaybeusefultoyou.Itincludesprimitivesthatmeasurehowmanytimestheproceduresinyourmodelarecalledduringarunandhowlongeachcalltakes.Youcanusethisinformationtowheretofocusyourspeedupefforts.

Caution:

Theprofilerextensionisexperimental.Itisnotyetwelltestedoruserfriendly.Nonetheless,wethinksomeuserswillfindituseful.

Howtouse

Theprofilerextensioncomespreinstalled.Tousetheextensioninyourmodel,addalinetothetopofyourCodetab:

extensions [profiler]

Ifyourmodelalreadyusesotherextensions,thenitalreadyhasanextensionslineinit,sojustaddprofilertothelist.


Example

setup ;; set up the modelprofiler:start ;; start profilingrepeat 20 [ go ] ;; run something you want to measureprofiler:stop ;; stop profilingprint profiler:report ;; view the resultsprofiler:reset ;; clear the data

ThankstoRogerPeppeforhiscontributionstothecode.

Primitives

profiler:callsprofiler:exclusive-timeprofiler:inclusive-timeprofiler:startprofiler:stopprofiler:resetprofiler:report

profiler:calls

profiler:callsprocedure-name

Reportsthenumberoftimesthatprocedure-namewascalled.Ifprocedure-nameisnotdefined,thenreports0.

profiler:exclusive-time

profiler:exclusive-timeprocedure-name

Reportstheexclusivetime,inmilliseconds,thatprocedure-namewasrunningfor.Exclusivetimeisthetimefromwhentheprocedurewasentered,untilitfinishes,butdoesnotincludeanytimespentinotheruser-definedprocedureswhichitcalls.

Ifprocedure-nameisnotdefined,thenreports0.

profiler:inclusive-time

profiler:inclusive-timeprocedure-name

Reportstheinclusivetime,inmilliseconds,thatprocedure-namewasrunningfor.Inclusivetimeisthetimefromwhentheprocedurewasentered,untilitfinishes.

Ifprocedure-nameisnotdefined,thenreports0.

profiler:start

profiler:start

Instructstheprofilertobeginrecordinguser-definedprocedurecalls.

profiler:stop

profiler:stop

Instructstheprofilertostoprecordinguser-definedprocedurecalls.

profiler:reset

profiler:reset

Instructstheprofilertoeraseallcollecteddata.

profiler:report

profiler:report

Reportsastringcontainingabreakdownofalluser-definedprocedurecalls.TheCallscolumncontainsthenumberoftimesauser-definedprocedurewascalled.TheInclT(ms)columnisthetotaltime,inmilliseconds,ittookforthecalltocomplete,includingthetimespentinotheruser-definedprocedures.TheExcl T(ms)columnisthetotaltime,inmilliseconds,spentwithinthatuser-definedprocedure,notcountingotheruser-defineproceduresitcalled.TheExcl/callscolumnisanestimateofthetime,inmilliseconds,spentinthatuser-definedprocedureforeachcall.

Hereisexampleoutput:

Sorted by Exclusive TimeName Calls Incl T(ms) Excl T(ms) Excl/calls

CALLTHEM 13 26.066 19.476 1.498CALLME 13 6.413 6.413 0.493REPORTME 13 0.177 0.177 0.014

Sorted by Inclusive TimeName Calls Incl T(ms) Excl T(ms) Excl/callsCALLTHEM 13 26.066 19.476 1.498CALLME 13 6.413 6.413 0.493REPORTME 13 0.177 0.177 0.014

Sorted by Number of CallsName Calls Incl T(ms) Excl T(ms) Excl/callsCALLTHEM 13 26.066 19.476 1.498

NetLogoRExtension

TheR-ExtensionofNetLogoprovidesprimitivestousethestatisticalsoftwareR(GnuS)(seetheRProjectwebsite)withinaNetLogomodel.ThereareprimitivestocreateR-VariableswithvaluesfromNetLogovariablesoragentsandotherstoevaluatecommandsinRwithandwithoutreturnvalues.

Using

Tousetheextensioninyourmodel,addalinetothetopofyourprocedurestab:

extensions [ r ]

Ifyourmodelalreadyusesotherextensions,thenitalreadyhasanextensionslineinit,sojustaddrtothelist.

FormoreinformationonusingNetLogoextensions,seetheExtensionsGuide.

ForexamplesoftheusageoftheR-Extension,modelscanbedownloadedfromtheprojectrepository.ThesemodelsareinstalledwithNetLogointhe“models”directoryoftheRextension.Pleasenotethat(asofNetLogo6.0)thesemodelsarenotincludedintheNetLogomodelslibrary.

SomeTips

Plotting

IfyouwanttousetheplotfunctionofR,youcouldactivatetheJavaGDplotdeviceviar:setPlotDevice,seethe“plot-example1.nlogo”model.Thisisthepreferedmethod!

ButyoucanalsousethestandardRdevice,butthen,youhavetogiveRsomecputime,e.g.byrunanevalulationofsys.sleep(0.01)withaforeverbutton.Seethe“plot-example2.nlogo”.(ManythankstoThomasPetzold!).Thecreationofplotsintofilesisalsopossible.Seethe“plot-into-file-example.nlogo”intheexamplesfolder.

LoadandSavedatafrom/intofile(s)

It’spossibletoloadandsavedatafromfiledirectlyinR.Thiscodesnippetillustrates:

r:eval "dataname <- read.table('<path to file>')" ; read filer:eval "write.table(dataname, file='<filename>')" ; write file

Data.framewithvectorincells

Normally,adata.framecellcontainsonlyasinglevalue.Eachcolumnisrepresentedasavectorandifyouwouldputavectorofvectorstoadata.frame,itwouldbesplittedintoseveralcolumns.WiththeR-Extensionitispossibletoputavectorintoadata.framecell,whenyouassignaNetLogoListtoacolumnwhichcontainsnestedNetLogoListsforeachrow.Ifyouwant,forexample,tousewrite.tableonthisdata.frame,youhavetomarkthiscolumnasclass="AsIs".YoucandothisbyusingtheI(x)-function.

Example:Ifthecolumnofinteresthasthename“col1”ofthedata.frame“df1”youcouldexecuter:eval "df1$col1 <-I(df1$col1)".Callhelp(I)fromwithinanRterminalforfurtherdetails.

LoadanR-Script

Furthermore,youcandefinefunctionsinanR-Script,loadit,andusethefunctions.LoadR-filesviar:eval "source('<pathto r-file>')".

LoadaPackage

It’salsopossibletoloadRpackagesviar:eval "library(<name of package>)".

Whenyoucompileyourcodecontainingextensions [r]youwillcreateanewRworkspace.Untilyoureloadtheextension,openanewmodelorsubmittheprimitive[r:clear](#rclear),allRvariablesassignedinthissessionwillbeavailablelikeyouwoulduseRfromthecommandlineorintheRConsole.

InteractiveShell

YoucanopenanInteractiveRShellviar:interactiveShell.ThisshellisaporttotheunderlayingRinstance.Thisshellworksontheglobalenvironment(seeEnvironmentsintheRExtensionbelow)whiletheextensionitselfworkonacustomlocalenvironment.Butthereisoneautomaticvariable“nl.env”intheglobalenvironment,whichisareferencetothelocalenvironmentoftheextension.Don’tdeletethisvariable!Youcanaccessavariablecreatedbytheextensionviaget("<variable name>",nl.env),forexamplemyvar <-get("myvar",nl.env).IfyouwanttoplotfromtheInteractiveShellyoushouldusetheincludedJavaGDplotdevice(see

http://www.r-project.org/

https://github.com/NetLogo/R-Extension/tree/master/examples

r:setPlotDevice).YoucansaveandloadthehistoryofenteredRcommandsviaaright-mousebuttoncontextmenu.

Pleasereadthenotesatthetopoftheoutputtextareaafteropeningtheshell!OnLinuxOSitcanhappenthatyouseeanerrormessagefromX11.Pleasecheck,ifeverythingworkedcorrecly.Ifso,youcanignorethesemessages.Ifnot,[email protected].

EnvironmentsIntheRExtension

WhenyouloadamodeltheR-ExtensioncreatesanewRenvironment.WhenyoucreateanRvariableusingtheR-Extension,thisvariableiscreatedinthelocalRenvironment.Furthermore,allcallsfromtheR-Extensionworkonthislocalenvironment.ThisnewenvironmentconceptenablesyoutousetheextensioninBehaviorSpaceExperiments.Therefore,youdon’thavetocareabouttheenvironmentwhileyou’renotusingtheInteractiveShellorothertools,whichworkontheglobalenvironment.Youcanexplicitlyassignavariabletotheglobalenvironmentbyusingthe<-operatororbyexecutingassign(<name>,<value>,envir=.GlobalEnv).IfyouworkwiththeInteractiveShell,seethenotesatthetopoftheoutputtextareaafteropeningtheshell.

Typehelp(environment)inanRshelltolearnmoreaboutenvironments.

Youcan/shouldclear(i.e.removeallvariableandfreememory)thelocalenvironmentvia[r:clearLocal](#rclearLocal).Ifyouwanttoclearalsotheglobalenvironment(thewholeworkspace),call[r:clear](#rclear).

Memory

WiththeR-ExtensionyoucanloadRintotheprocessofNetLogo.BecauseofthearchitectureofR,bothsoftwareshareonesystemprocessandthereforethememorygiventoNetLogo.

InsomecircumstancesitcanhappenthatyoureceiveanoutofmemoryerrorduetoJava’sheapspace.YoucanincreasetheheapspacebeforestartingNetLogobyadaptingthe-XmxJVM-parameter(seealsotheNetLogomanualsectiononWindowsmemory).Buton32-bitsystems,thisisverylimited.Therefore,itisagoodideatousea64-bitsystemifyouwant/needtousehighamountofRAM.YoucanseethememoryusageofRbystartingtheinteractiveshell(r:interactiveShell)andtypethere:memory.size(max=F)andmemory.size(max=T).Furthermore,youcancheckthememorylimitbytyping:memory.limit().Seealso:

Rmanualpageformemory.profileRmanualpageforobject.sizeRmanualpageformemory.size

Ifyoucallthegarbagecollectorintheinteractiveshellbytypinggc(),youwillgetsomeinformationaboutthecurrentmemoryusage(seealsohttp://stat.ethz.ch/R-manual/R-patched/library/base/html/gc.html).

Ifyoutypegc(nl.env)youwillseethepercentageofmemoryusedforconscellsandvectors.

Don’tforgettocallther:gcprimitiveafterremovinganRvariableanddon’tforgettoremoveRvariableyoudon’tneedanymore!Seehowthememoryusagechangesafterremovingvariableandcallingr:gc.

Ifyouusetoomuchmemory,itcanhappen,thatNetLogowillcloseabruptly.Insuchacase,checkifthereisawaytoreducethememoryused.Ifnot,trytoswitchovertotheRserve-extension.WiththeRserve-Extensionbothsoftware,NetLogoandR,runindependently.Thereis,ofcause,alsoalimitoftransferabledataamountwithonerequest,butitislessrestrictive.

Onelastnotetothistopic:KeepinmindthatRisavector-orientedlanguage.Preventmasscallswithsinglevalueswheneverpossibleandreplacethembyvectoroperations.Thisismuchfasterandmorestable.

Headless

SinceR-Extensionversion1.1itispossibleusetheextensionwhenNetLogoisrunninginheadlessmode.Thisisforexamplethecase,whenyourunBehaviorSpaceexperimentsfromthecommandline(seehere).Thedifferenceis,thattheinteractiveShellisnotinitialized/instanciated.YoucanusetheextensionasyouknowitfromGUImode,butitisnotpossibletoopentheinteractiveShell(r:interactiveShell)andtosettheplotdevice(r:setPlotDevice).Butoneadditionalthingshastobedone:Youhavetocallr:stopfinallywhenrunningNetLogoheadlesstostoptheRengine.OtherwiseNetLogowillnotbeclosedandyouwillnotgetbacktothecommandlineprompt.WhensettingupaBehaviorSpaceexperiment,thereistheoptiontosetfinalcommands.Thisisagoodplacetoaddther:stopcommand(seeimage).


https://github.com/NetLogo/R-Extension/issues

http://stat.ethz.ch/R-manual/R-patched/library/base/html/memory.profile.html

http://stat.ethz.ch/R-manual/R-patched/library/utils/html/object.size.html

http://stat.ethz.ch/R-manual/R-devel/library/utils/html/memory.size.html

http://stat.ethz.ch/R-manual/R-patched/library/base/html/gc.html

http://rserve-ext.sourceforge.net/

Installing

TheRExtensionisbundledwithNetLogo6.Touseit,youwillneedacompatibleRinstallationandyoumayneedtoconfiguretheextension.

InstallingR

StandardR3installationsshouldwork(sometimeswithoutconfiguration).AsofNetLogo6,thefollowingoperatingsystem/Rversionsweretested:

MacOSX,R3.3.2Windows10,R3.3.2Ubuntu14.04(64-bit),R3.0.2

OnceRisinstalled,youwillneedtoinstalltherJavapackage.CertainfeaturesoftheRextensionrelyontheJavaGDpackage.

Toinstall,starttheRGuifromyourprogramlist,clickontheitem“Packages”inthemenubarandthenon“InstallPackage(s)”.Selectyourfavoriteserverandfind“rJava”,aswellas“JavaGD”and/or“CommonJavaJars”(bothoptional)inthelistofpackages.

Ifyoupreferusingtheconsole,youcaninstallthesamepackagesbyrunningthefollowingcommandsintheconsole(andfollowingthepromptstheygenerate,asappropriate).

install.packages("rJava")install.packages("JavaGD") # Optionalinstall.packages("CommonJavaJars") # Optional

ConfiguringtheRextension

IfyouareusingLinuxorMacOSandoneoftheaboveRversions,youmaynotneedtoperformanyfurtherconfiguration.AneasywaytodeterminewhetheryouneedtoconfiguretheextensionittoopenanewNetLogomodel,addextensions [r ]tothecodetabandpress“Check.”Ifyouseeanerror,youneedtoconfiguretheRextension.TheRextensioncanbeconfiguredbyeditingthe“user.properties”fileinatexteditor(“user.properties”islocatedintherextensiondirectoryaspartoftheNetLogoinstallation).Thefollowingkeysareusedtoconfiguretheextension:

r.home:Controlswhichinstallationofrisused.jri.home.paths:ControlsthepathtothejrisubdirectoryoftherJavalibrary.

NotethatyouwillhavetoexitNetLogoandrestarttoseeconfigurationchangestakeeffect,astheconfigurationfileisonlyloadedonceperNetLogoinstance.Seebelowonhowtodeterminetheappropriatevaluestoforr.homeandjri.home.paths.

ConfiguringtheWindowsPATH

WindowsrequiresanadditionalconfigurationsteptomaketheRextensionfullyfunctional.TheappropriatedirectoryfromyourRinstallationneedstobeaddedtoyourPATH.Todothis,determinewhereyourRinstallationislocated(herewe’llusethelocationC:\ProgramFiles\R\R-),thenfollowthesesteps.

1. OpentheSystemPropertiesdialog.Youcantype“EnvironmentVariable”intoCortanaornavigatetherethrough“ControlPanel”>System>“Advancedsystemsettings”.

2. Clickthe“Environmentvariables…”buttoninthelowerrightofthedialog.3. Clickthe“Path”variableinthelowerpanel,thenclickthelower“Edit…”button.4. Windows10allowsyoutochoose“New”andenteraseparatepath.Ifyou’reusingWindows7,appendthevalue,usinga

semicolontoseparateitfromtheentrybefore.

Ifyou’reusing32-bitNetLogo,enterthelocationC:\Program Files\R\R-<version>\bin\i386\Ifyou’reusing64-bitNetLogo,enterthelocationC:\Program Files\R\R-<version>\bin\x64\

1. ChooseOK,andOKagain2. LogoutofyouruserandbackinorrestartWindowstoletthesettingtakeaffect.

NotethatyouwillneedtoupdatethissettingifyouwishtoupgradetheversionofRusedbyNetLogo.

Notesonediting“user.properties”onWindows

“user.properties”isanewline-delimitedfile.Thismeansifitisopenedin“Notepad”itwilllooklikeallthetextisonasingleline.Forthisreason,itisrecommendedtoopenfirstin“WordPad”andresavebeforeeditinginNotepad.Alternatively,ifyouhaveafull-featuredtexteditor(likeNotepad++,Vim,orEmacs)installed,youcanusethattoeditthefile.

Toreiterateawarninggiveninthe“user.properties”file,thedirectoryseparatorforWindowsmustbeenteredinuser.propertiesasdouble-backslash(“\”)orsingle-forward-slash(“/”).

Determiningr.homeandjri.home.paths

r.homeisthepathtothe“R”installationdirectorywhichcontainsthe“bin”directory.Ifyou’rehavingtroublefindingthis,youcanrunR.home(component = "home") inR,orR RHOMEonthecommandline(ifRisonyourpath).

R.home(component = "home")# Returns "C:/PROGRA~1/R/R-33~1.2/bin/x64" on Windows.# Will return other results on other platforms or configurations

jri.home.pathsisalistofdirectoriestocheckforjri.It’sinthejridirectoryundertherJavalibraryinstallation.YoucanfindthejridirectoryintherJavapackagebyrunningthefollowinginR:

system.file("jri", package = "rJava")# Returns "C:/Users/username/Documents/R/win-library/3.3/rJava/jri" on Windows.# Will return other results on other platforms or configurations

Takethepathandedittheuser.propertiesfile,uncommentingandeditingonesetofr.homeandjri.home.pathstomatchthevaluesobtainedinR.Whenyou’redone,theuser.propertiesfileshouldhavethefollowinglines(giventheaboveresults):

r.home=C:/PROGRA~1/R/R-33~1.2/bin/x64jri.home.paths=C:/Users/username/Documents/R/win-library/3.3/rJava/jri

Saveuser.propertiesandloadamodelusingtheRextension.Youshouldseeitstartandrunproperly.

Primitives

r:clearr:clearLocalr:evalr:__evaldirectr:gcr:getr:interactiveShellr:putr:putagentr:putagentdfr:putdataframer:putlistr:putnamedlistr:setPlotDevicer:stop

r:clear

r:clear

ClearstheR-Workspace.AllvariablesinRwillbedeleted.ItevaluatestheRcommandrm(list=ls())andrm(list=ls(nl.env)).Thisdeletesvariablescreatedinglobalaswellaslocalenvironment(seeREnvironmentsfordetailsaboutenvironments).It’salwaysagoodideatoaddthiscommandtoyoursetupprocedureunderyour“clear-all”call.

;; clear the R workspacer:clear

r:clearLocal

r:clearLocal

ItclearsthelocalRenvironment,whichisusedbytheextension.Allvariableswhichhavebeencreatedinthelocalenvironmentwillbedeleted.ItevaluatestheRcommandrm(list=ls(nl.env)).SeeREnvironmentsfordetailsaboutenvironments.Seer:clearfordeletingallvariables,i.e.theglobalsaswell.

;; delete the local variablesr:clearLocal

r:eval

r:evalR-command

ItevaluatesthesubmittedRcommand.TheRcommandshouldn’treturnavalue.

;; creates a new vector in R with a sequence from 1 to 10r:eval "x <- seq(1,10)"show r:get "x"

r:__evaldirect

r:__evaldirectR-command

EvaluatesthesubmittedRcommandintheglobalenvironment(notinthelocalenvironmentliker:evaldoes)andwithoutacheck(notusingtry-functioninternally).ThiscanbenecessaryforsomeRpackages,likegglopt2.Pleasenote,thatyoucanproducenameclasheswhencreatingnewvariablesusingthisprimitive.Thevariablewillbecreatedintotheglobalenvironmentandwillnotoverwritevariablewiththesamenamethathavebeencreatedintothelocalenvironment.Ifyourequestavariablewithr:getitwillsearchinthelocalenvironmentfirst.Therefore,iftherearevariableswiththesamenameinthelocalandtheglobalenvironment,itwillreportthevariablefromthelocalenvironmentandnotthevariablecreatedviar:__evaldirect.Ifthereisonlyavariablewiththerequestednameintheglobalenvironment,everythingwillbefine-r:getwillreportthevalueofthisvariable.Ifyouwanttoremoveavariablecreatedviar:__evaldirect,i.e.intheglobalenvironment,callr:eval "rm(myvar, envir=.GlobalEnv)",replacemyvarbythenameofyourvariable.TheRcommandshouldn’treturnavalue.Thisprimitiveisexperimental.

;; creates a new vector in R with a sequence from 1 to 10r:__evaldirect "x <- seq(1,10)"show r:get "x"

r:gc

r:gc

CallsthegarbagecollectorofJava(i.e.theR-Extension)andR.CallthisprimitiveafterremovinganRvariabletofreethememory.

;; create a variabler:eval "x <- 1:10";; remove the variabler:eval "rm(x)";; call the garbage collectorr:gc

r:get

r:getR-command

ReportsthereturnvalueofthesubmittedRcommand.ReturntypecouldbeaString,Number,Boolean,NetLogoListoraNetLogoListofLists.

RlistswillbeconvertedintoaNetLogoList.IftheRlistitselfcontainsfurtherlists,itwillbeconvertedintoaNetLogoListwithnestedNetLogolists.Listscontainingvaluesofdifferentdatatypesarealsosupported(e.g.mixedStrings,NumbersandBooleans/Logicals).

Data.frameswillbeconvertedintoaNetLogoListwithnestedListforeachcolumn,butthecolumnnameswillbelost(samefornamedRlists).

Rmatricescanbereceived,buttheyareconvertedintooneNetLogolist.NULLandNAvaluesarenotconvertedandwillthrowanerror,becauseNetLogohasnocorrespondingvalue.

;; returns a list with 10 variablesshow r:get "rnorm(10)"

r:interactiveShell

r:interactiveShell

Opensawindowwithtwotextareas.TheupperoneistheRoutputstreamandintheloweroneyoucantypeRcommands.ThisistheaccesstotheunderlayingRsession.Youcantypemulti-linecommands.TosubmitcommandspressCtrl+Enter.With“PageUp”and“PageDown”intheinputareayoucanbrowsethroughthehistroyofsubmittedcommands.Withright-mouseclickcontextmenu,youcansaveandloadanRHistory(interchangeablewithRterminalandotherRGUIs).

Pleasenote,thattheInteractiveShellworksontheglobalenvironment,whilecommandssubmittedfromNetLogolivesinanlocalenvironment.Areferencetothislocalenvironmentisautomaticallyaddedtotheglobalenvironment(namednl.env,pleasedonotdeletethisvariable.Withacallofr:clearyoucanrestoreitbutthiswillemptyyourworkspace).YoucanusethistohaveaccesstovariableswhichyouhavecreatedfromNetLogobyget("<variable name>",nl.env).Tocopyforexampleanvariablewiththenamevar1fromthelocalenvironmenttotheglobalenvironment,typevar <-get("var",nl.env).SeesectionREnvironmentsfordetails.Ifyoujustwanttoseethecontentsofavariablewhichlivesinthelocalenvironment,youcouldsubmityourcommand,forexampleintheNetLogoCommandCenter,andtheresultwillbeshownintheoutputareaoftheInteractiveShell.Forexample:

r:put "test" (list world-width world-height)r:interactiveShellr:eval "print(test)"r:eval "str(test)"

VariableswhichhavebeencreatedintheInteractiveShellareavailablefromNetLogo,eveniftheyarecreatedintheglobalenvironment.Butifthereisavariablewiththesamenameinthelocalenvironment,youwillgetthisvariableinNetLogoinsteadtheonefromtheglobalenvironment.

IfyouwanttoexecuteplotcommandsfromtheInteractiveShellyoushouldactivatetheintegratedJavaGDplotdeviceviar:setPlotDevicefirst.

;; opens Interactive Shellr:interactiveShell

r:put

r:putnamevalue

CreatesanewvariableinRwiththenamename.ThevaluecanbeaString,Number,BooleanorList.

NetLogoListsareconvertedtoRvectors,ifallentriesareofthesamedatatype.IfaNetLogolistcontainsdifferentdatatypes(mixedStrings,NumbersofBooleans),itwillbeconvertedintoanRlist.IfaNetLogoListcontainsother/nestedNetLogoListsitwillbeconvertedintoanRlistandthenestedListsarehandledbythesamerule(Vectorsifallitemsareofthesamedatatype,…).

;; creates an R variable "testvar" with the size of turtle 0r:put "testvar" [size] of turtle 0show r:get "testvar"

r:putagent

r:putagentnameagentvariablesr:putagentnameagentsetvariables

CreatesanewnamedlistinRwiththenamename.Theargumentvariablesisanynumberofstringswhichlistandvariable(s)oftheagent|agentset.NamesoftheelementsoftheRlistwillbethesameasthenamesoftheagentvariables.Turtleswillbeassignedinascendingorderoftheirwho-variable.Patcheswillbeassignedinlinesfromupperlefttolowerright.Sincetheargumentsofthisprimitivearerepeatable,don’tforgettheparenthesesaroundthestatement.

;; creates an R-list "agentlist1" with the size and the id of turtles, don't forget the parentheses(r:putagent "agentlist1" turtles "size" "who")show r:get "agentlist1$who";; creates an R-list "agentlist2" with the pcolor, pxcor and pycor of patches(r:putagent "agentlist2" patches "pcolor" "pxcor" "pycor")show r:get "agentlist2$pcolor"

r:putagentdf

r:putagentdfnameagentvariables

r:putagentdfnameagentsetvariables

Sameasr:putagentbutcreatesanRdata.frameinsteadalist.Pleasereadthenotesaboutdata.framesifoneofyouragentvariablescontainsNetLogoLists.

;; creates an R-list "agentlist2" with the pcolor, pxcor and pycor of patches, don't forget the parentheses(r:putagentdf "df1" patches "pcolor" "pxcor" "pycor")show r:get "class(df1)"

r:putdataframe

r:putdataframenamevarnamevaluer:putdataframenamevarnamevaluevarname2value2...

Sameasr:putnamedlistbutcreatesanRdata.frameinsteadofalist.IfyousendmorethanonelisttoNetLogoandthelistsareofdifferentlength,thesmalleroneswillbefilledwithNAvalues.

IfyousendnestedLogoLists(e.g.oftype:[[][]…])toonecolumnpleasereadthenotesaboutdataframeswithvectorsincells.

;; creates an R-list "agentlist2" with the pcolor, pxcor and pycor of patches, don't forget the parentheses(r:putdataframe "df1" "v1" [12 13 14 15 16] "v2" ["foo1" "foo2" "foo3" "foo4" "foo5"] "v3" [1.1 2.2 3.3 4.4 5.5])show r:get "df1$v3"

r:putlist

r:putlistnamevalue

CreatesanewlistinRwiththenamename.VariableisrepeatableandcanbeaNumber,BooleanorList.Each“Variable”willgetthenameofitsposition(1,2,3,…).Sincetheargumentsofthisprimitivearerepeatable,don’tforgettheparenthesesaroundthestatement.

;; creates an R-list "list1", don't forget the parentheses(r:putlist "list1" 25.5 [25 43 32 53] "testvalue" [44.3 32.32 321.2 4.2])show r:get "class(list1)"show r:get "list1[[1]]"show r:get "list1$'0'"show r:get "list1[[2]]"

r:putnamedlist

r:putnamedlistnamevarnamevaluer:putnamedlistnamevarnamevaluevarname2value2...

CreatesanewnamedlistinRwiththenamename.Variablenamesandvaluesfollowinalternatingsequenceandmayberepeatedasmanytimesasdesired.ValuescanbeaNumber,BooleanorList.Eachvaluewillgetthenamevarname.Sincetheargumentsofthisprimitivearerepeatable,don’tforgettoputthestatementintoparentheses.

;; creates an R-list "list1" , don't forget the parentheses(r:putnamedlist "list1" "v1" 25.5 "v2" [25 43 32 53] "v3" "testvalue" "v4" [44.3 32.32 321.2 4.2])show r:get "class(list1)"show r:get "list1[[1]]"show r:get "list1$v1"

r:setPlotDevice

r:setPlotDevice

ToopenanRplotinawindowyoucanusetheJavaGDplotdevice.WiththisprimitiveyoucanactivatethisdeviceandallfollowingcallsofRplotswillbeprintedwiththisdevice.

Tousethisdevice,youhavetoinstalltheJavaGDpackageinR.OpenanRterminalortheInteractiveShell(seer:interactiveShell)andtypeinstall.packages("JavaGD").

Withthisplotwindowyoucansavetheplottoanfileofdifferentgraphictypeandyoucancopytheplottotheclipboard.Pleasenote,thatonLinuxOSitcanbenecessarytoallowtoaddimagestotheclipboard(e.g.inKDEyouhavetoconfigureKLIPPERtoallowimages).Theresolutionforrasterimagesdependsonthesizeoftheplotwindow.Ifyouneedhighresolutionmaximazethewindow(anddon’tusejpeg,becausethedriverisbad)orbetteruseavectorimageformat.

Pleaseseethenotesaboutplottingforotherdetails.

;; activate the JavaGD plot devicer:setPlotDevice

r:stop

r:stop

StopstheRengine.Thisisneeded(only)ifNetLogoisrunninginheadlessmode,forexamplewhenrunningBehaviorSpaceexperimentsfromthecommandlinewithsomethinglikethis:

java -cp NetLogo.jar org.nlogo.headless.Main --model mymodel.nlogo --experiment exp1 --table outtab1.csv

Shouldbethelastcallinheadlesssimulation.Seeusagenotesabovefordetails.

r:stop

Troubleshooting

Belowaresomecommonproblemsandsomeideasonhowtoremedythem.PleasekeepinmindthatweplantocontinuetoimprovetheRextensionfollowingthereleaseofNetLogo6.Wewelcomefeedbackonhowtoimprovetheextensionaswellasbugreportspointingustoanynewproblemsyouencounter.

LoadingRpackagesfails

See,forexample,thispost.

AfterchangingtheworkingdirectoryinR(e.g.withsetwd())NetLogodoesn’tfindtheextension

ChangingworkingdirectoryinRdoesn’tworkbecauseitchangesalsoJava’slibrarypaththatNetLogoneedstofinditsextensions.PleaseuseabsolutepathtoanyfilesinRinsteadofchangingtheworkingdirectory.

Specificerrorcodelist

Error#01.InvalidRHome.RhomeisspecifiedviatheR_HOMEenvironmentvariableorapropertiesfile,butcouldn’tbefoundatthespecifiedpath.SeeaboveforhowtospecifyRhome.Error#02:CannotfindrJava/JRI.TheRExtensionwasunabletolocateyourinstallationofrJava.Somestepstoresolve:EnsurethatrJava(0.9-8orlater)isinstalledinR.Ensurethatit’sinstalledeithersystem-wideorforyouasauserEnsurethatyourconfigurationpointstotheproperrJavalocation.Ifyouhaveauser.propertiesfile,ensurethatjri.home.pathsincludesthepathgivenbyRwhenyourunsystem.file("jri",package="rJava")Error#03:CannotloadrJavalibraries.ThismayindicateacorruptedrJavainstallation.TryreinstallingrJava.Error#04:ErrorinR-Extension.Thisisanunknowninitializationerror.EnsurethatyouarerunningR3.0.0orlaterandhavetherJavaextensioninstalled(version0.9-8orlater).Pleasereportthiserrortobugs@ccl.northwestern.eduoropenanewissueontheR-Extensionissuetracker.Error#05:TherewasanerrorsettingR_HOME.Checkyouruser.propertiesfiletoensurethatr.homespecifiesavalidpathtotheRextension.YoumayalsobeabletoworkaroundthiserrorbysettingtheR_HOMEenvironmentvariable.Ifthiserrorpersists,pleasereportit!Error#06:CannotloadRlibraries.ThismayindicateacorruptedorimproperlyconfiguredRinstallation.Ifyou’recertainthatyourRinstallationisfind,pleasereportthisasanissue.

Citation

Thiele,JC;Grimm,V(2010).NetLogomeetsR:Linkingagent-basedmodelswithatoolboxfortheiranalysis.EnvironmentalModellingandSoftware,Volume25,Issue8:972-974[DOI:10.1016/j.envsoft.2010.02.008]

CopyrightandLicense

TheRextensionisCopyright(C)2009-2016JanC.ThieleandCopyright(C)2016UriWilensky/TheCenterforConnectedLearning.

NetLogo-R-Extensionisfreesoftware;youcanredistributeitand/ormodifyitunderthetermsoftheGNUGeneralPublicLicenseaspublishedbytheFreeSoftwareFoundation;eitherversion2oftheLicense,or(atyouroption)anylaterversion.

Thisprogramisdistributedinthehopethatitwillbeuseful,butWITHOUTANYWARRANTY;withouteventheimpliedwarrantyofMERCHANTABILITYorFITNESSFORAPARTICULARPURPOSE.SeetheGNUGeneralPublicLicenseformoredetails.

YoushouldhavereceivedacopyoftheGNUGeneralPublicLicensealongwithNetLogo-R-Extension(locatedinGPL.txt).Ifnot,seehttp://www.gnu.org/licenses/.

https://beta.groups.yahoo.com/neo/groups/netlogo-users/conversations/topics/18786?reverse=1


https://github.com/NetLogo/R-Extension/issues

http://www.gnu.org/licenses/

NetLogoRndExtension

ThisextensionaddstheabilitytodoroulettewheelselectioninNetLogo.ItprovidesasimplerwaytoaccomplishthesamethingastheLotteryExamplefromtheNetLogoModelsLibrary.

Usage

Whichprimitivetousedependsonwhetheryouwanttoselectanitemfromalistorfromanagenset.Italsodependsonwhetheryouwantoneormanyitemsand,ifyouwantmany,ifrepeatsareallowedornot.Thefollowingtablesummarizesthesituation:

FromanAgentSet FromaListOneitem rnd:weighted-one-of rnd:weighted-one-of-list

Manyitems,withoutrepeats rnd:weighted-n-of rnd:weighted-n-of-list

Manyitems,withrepeats rnd:weighted-n-of-with-repeats

rnd:weighted-n-of-list-with-repeats

(Note:theinitialversionoftheextensionhadasinglesetofprimitivesforbothlistsandagentsets,butitturnedouttobeconfusing,sowechangedit.Ifyouwereusingtheoldversionoftheextension,youwillneedtomodifyyourcodetousethenewprimitives.)

Inallcases,youwillneedtoprovidetwothingstotheprimitive:

The“candidates”:theitemsthattheprimitivewillselectfrom.The“weight”:howlikelyitisforeachcandidatetobeselected.

Ifyouwanttoselectmorethanoneitems,youwillalsoneedtotellit:

Howmanyitemstoselect.

Anoteaboutperformance

TheextensionusesKeithSchwarz’simplementationofVose’sAliasMethod(seeSchwarz’sDarts,Dice,andCoinspage).Assumingyouarechoosingncandidatesforacollectionofsizemwithrepeats,thismethodhasaninitializationcostofO(m)followedbyacostofO(1)foreachitemyoupick,soO(m+n)overall.

Forexample,inthefollowingcode:

let candidates n-values 500 [ [n] -> n ]rnd:weighted-n-of-list-with-repeats 100 candidates [ [w] -> w ]n-values 100 [ rnd:weighted-one-of-list candidates [ [w] -> w ] ]

…thelineusingrnd:weighted-n-of-list-with-repeatswilllikelyrun100timesfasterthanthelineusingacombinationofn-valuesandrnd:weighted-one-of-list.Thisisbecausernd:weighted-n-of-list-with-repeatsonlyinitializesthealgorithmonceandrnd:weighted-one-ofdoesiteachtimeitiscalled.

(Notethatcomposingn-valueswithrnd:weighted-one-of-listdoesnotpreservetheorderoftheoriginalcandidatelist,whilernd:weighted-n-of-list-with-repeatsdoes.)

Thingsareabitmorecomplicatedifyouarechoosingwithoutrepeats,however.Inthiscase,thealgorithmmayhavetodiscardsomepicksbecausethecandidateshavealreadybeenselected.Whenthisstartshappeningtoooften(maybebecausesomeweightsaremuchbiggerthanothers),theextensionre-initializesthealgorithmwiththealready-picked

https://en.wikipedia.org/wiki/Fitness_proportionate_selection

https://github.com/NetLogo/models/blob/master/Code Examples/Lottery Example.nlogo

http://www.keithschwarz.com/darts-dice-coins/

candidatesexcluded.Thisshouldnothappentoooften,however,sowhilepickingwithoutrepeatshasanupperboundofO(m*n)intheory,itshouldusuallynotbemuchmorethanO(m+n)inpractice.

Thepreviousremarksapplytoagentsetprimitivesasmuchastheyapplytolistprimitives.

Primitives

AgentSetPrimitives

rnd:weighted-one-ofrnd:weighted-n-ofrnd:weighted-n-of-with-repeats

ListPrimitives

rnd:weighted-one-of-listrnd:weighted-n-of-listrnd:weighted-n-of-list-with-repeats

rnd:weighted-one-of

rnd:weighted-one-ofagentsetreporter

Reportsarandomagentfromagentset.

Theprobabilityofeachagentbeingpickedisproportionaltotheweightgivenbythereporterforthatagent.Theweightsmustnotbenegative.

Iftheagentsetisempty,itreportsnobody.

HereisafullrewriteoftheLotteryExamplemodelusingthernd:weighted-one-ofprimitive:

extensions [ rnd ]

to setup clear-all ; create a turtle on every fifth patch ask patches with [ pxcor mod 5 = 0 and pycor mod 5 = 0 ] [ sprout 1 [ set size 2 + random 6 ; vary the size of the turtles set label 0 ; start them out with no wins set color color - 2 ; make turtles darker so the labels stand out ] ] reset-ticksend

to go ask rnd:weighted-one-of turtles [ size ] [ set label label + 1 ] tickend

rnd:weighted-n-of

rnd:weighted-n-ofsizeagentset[reporter]

Reportsanagentsetofthegivensizerandomlychosenfromtheagentset,withnorepeats.

Theprobabilityofeachagentbeingpickedisproportionaltotheweightgivenbythereporterforthatagent.Theweightsmustbenon-negativenumbers.

Itisanerrorforsizetobegreaterthanthesizeoftheagentset.

If,atsomepointduringtheselection,thereremainsonlycandidateswithaweightof0.0,theyallhaveanequalprobabilityofgettingpicked.

rnd:weighted-n-of-with-repeats

rnd:weighted-n-of-with-repeatssizeagentset[reporter]

Reportsalistofthegivensizerandomlychosenfromtheagentset,withrepeats.(Whyalistinsteadofanagentset?Becauseanagentsetcannotcontainthesameagentmorethanonce.)

Theprobabilityofeachagentbeingpickedisproportionaltotheweightgivenbythereporterforthatagent.Theweightsmustbenon-negativenumbers.

Itisnotanerrorforsizetobegreaterthanthesizeoftheagentset,buttherehastobeatleastonecandidate.


Ifallweightsare0.0,eachcandidatehasanequalprobabilityofbeingpicked.

rnd:weighted-one-of-list

rnd:weighted-one-of-listlistanonymous-reporter

Reportsarandomitemfromlist.

Theprobabilityofeachitembeingpickedisproportionaltotheweightgivenbytheanonymous-reporterforthatitem.Theweightsmustnotbenegative.Thefirstargumentpassedtotheanonymousprocedurereferstothelistitem.(SeetheAnonymousProceduressectionoftheProgrammingGuideformoredetails.)

Itisanerrorforthelisttobeempty.

Acommonwaytousetheprimitiveistohavealistoflists,wherethefirstitemofeachsublististhethingyouwanttochooseandtheseconditemistheweight.Hereisashortexample:

let pairs [ [ "A" 0.2 ] [ "B" 0.8 ] ]repeat 25 [ ; report the first item of the pair selected using ; the second item (i.e., `last p`) as the weight type first rnd:weighted-one-of-list pairs [ [p] -> last p ]]

ThisshouldprintBroughlyfourtimesmoreoftenthanitprintsA.

Ifyouhappentohaveyouritemsandyourweightsintwoseparatelists,youcancombinethemintopairsbyusingacombinationofmapandlist:

let items [ "A" "B" "C" ]let weights [ 0.1 0.2 0.7 ]let pairs (map list items weights)

Sinceweapplymaptoboththeitemslistandtheweightslist,theparenthesesareneededin(map list items weights).Wealsousetheconciseanonymousproceduresyntax(seethe

programmingguide)topasslistasthereporterformap.Thesamethingcouldhavebeenwritten(map [ [a b] -> list a b ] items weights) .

rnd:weighted-n-of-list

rnd:weighted-n-of-listsizelistanonymous-reporter

Reportsalistofthegivensizerandomlychosenfromthelistofcandidates,withnorepeats.


Itisanerrorforsizetobegreaterthanthesizeofthelist of candidates.


Theitemsintheresultinglistappearinthesameorderthattheyappearedinthelistofcandidates.(Ifyouwanttheminrandomorder,useshuffleontheresult).

Example:

let candidates n-values 8 [ [n] -> 2 ^ (n + 1) ] ; make a list with the powers of twoprint rnd:weighted-n-of-list 4 candidates [ [w] -> w ]

Thisshouldprintalistoffournumbers,wherethebiggernumbers(32,64,128,256)haveamuchbetterchancetoshowupthanthesmallerones(2,4,8,16).

rnd:weighted-n-of-list-with-repeats

rnd:weighted-n-of-list-with-repeatssizelistanonymous-reporter

Reportsalistofthegivensizerandomlychosenfromthelistofcandidates,withrepeats.


Itisnotanerrorforsizetobegreaterthanthesizeofthelistofcandidates,buttherehastobeatleastonecandidate.


Ifallweightsare0.0,eachcandidatehasanequalprobabilityofbeingpicked.

Theitemsintheresultinglistappearinthesameorderthattheyappearedinthelistofcandidates.(Ifyouwanttheminrandomorder,useshuffleontheresult).

Example:

let pairs [ [ "A" 0.2 ] [ "B" 0.8 ] ]print map first rnd:weighted-n-of-list-with-repeats 25 pairs [ [p] -> last p ]

Thisshouldprintalistof25AsandBs,withroughlyfourtimesasmanyBsthanAs.

NetLogoSoundExtension

Using

TheSoundExtensionletsNetLogomodelsmaketwokindsofsounds:MIDIsoundsandplaybackofpre-recordedsoundfiles.

TheJavaAPIsusedarejavax.sound.midiandjava.applet.AudioClip.

HowtoUse

Thesoundextensioncomespreinstalled.Tousetheextensioninyourmodel,addthisatthetopofyourCodetab:

extensions [sound]

Ifyourmodelalreadyusesotherextensions,thenitalreadyhasanextensionslineinit,sojustaddsoundtothelist.


Forexamplesthatusethesoundextension,seetheSoundsectionunderCodeExamplesintheNetLogoModelsLibrary.

MIDIsupport

TheMIDIpartoftheextensionsimulatesa128-keyelectronickeyboardwith47drumsand128melodicinstruments,asprovidedbyGeneralMIDILevel1specification.

Itsupports15polyphonicinstrumentchannelsandasinglepercussionchannel.Usingmorethan15differentmelodicinstrumentssimultaneouslyinamodelwillcausesomesoundstobelostorcutoff.

Thepitchofamelodicinstrumentisspecifiedbyakeynumber.Thekeysonthekeyboardarenumberedconsecutivelyfrom0to127,where0istheleft-mostkey.MiddleCiskeynumber60.

Theloudnessofaninstrumentisspecifiedbyavelocity,whichrepresentstheforcewithwhichthekeyboardkeyisdepressed.Velocityrangesfrom0to127,where64isthestandardvelocity.Ahighervelocityresultsinaloudersound.

Primitives

sound:drumssound:instrumentssound:play-drumsound:play-notesound:play-note-later

sound:drums

sound:drums

Reportsalistofthenamesofthe47drumsforusewithsound:play-drum.

http://www.midi.org/about-midi/gm/gm1_spec.shtml

sound:instruments

sound:instruments

Reportsalistofthenamesofthe128instrumentsforusewithsound:play-note,sound:play-note-later,sound:start-noteandsound:stop-note.

sound:play-drum

sound:play-drumdrumvelocity

Playsadrum.

Example:

sound:play-drum "ACOUSTIC SNARE" 64

sound:play-note

sound:play-noteinstrumentkeynumbervelocityduration

Playsanoteforaspecifiedduration,inseconds.Theagentdoesnotwaitforthenotetofinishbeforecontinuingtonextcommand.

;; play a trumpet at middle C for two secondssound:play-note "TRUMPET" 60 64 2

sound:play-note-later

sound:play-note-laterdelayinstrumentkeynumbervelocityduration

Waitsforthespecifieddelaybeforeplayingthenoteforaspecifiedduration,inseconds.Theagentdoesnotwaitforthenotetofinishbeforecontinuingtonextcommand.

Example:

;; in one second, play a trumpet at middle C for two secondssound:play-note-later 1 "TRUMPET" 60 64 2

DrumNames

35. Acoustic Bass Drum 59. Ride Cymbal 236. Bass Drum 1 60. Hi Bongo37. Side Stick 61. Low Bongo38. Acoustic Snare 62. Mute Hi Conga39. Hand Clap 63. Open Hi Conga40. Electric Snare 64. Low Conga41. Low Floor Tom 65. Hi Timbale42. Closed Hi Hat 66. Low Timbale43. Hi Floor Tom 67. Hi Agogo44. Pedal Hi Hat 68. Low Agogo

45. Low Tom 69. Cabasa47. Open Hi Hat 70. Maracas47. Low Mid Tom 71. Short Whistle48. Hi Mid Tom 72. Long Whistle49. Crash Cymbal 1 73. Short Guiro50. Hi Tom 74. Long Guiro51. Ride Cymbal 1 75. Claves52. Chinese Cymbal 76. Hi Wood Block53. Ride Bell 77. Low Wood Block54. Tambourine 78. Mute Cuica55. Splash Cymbal 79. Open Cuica56. Cowbell 80. Mute Triangle57. Crash Cymbal 2 81. Open Triangle58. Vibraslap

InstrumentNames

*Piano* *Reed*1. Acoustic Grand Piano 65. Soprano Sax2. Bright Acoustic Piano 66. Alto Sax3. Electric Grand Piano 67. Tenor Sax4. Honky-tonk Piano 68. Baritone Sax5. Electric Piano 1 69. Oboe6. Electric Piano 2 70. English Horn7. Harpsichord 71. Bassoon8. Clavi 72. Clarinet

*Chromatic Percussion* *Pipe*9. Celesta 73. Piccolo10. Glockenspiel 74. Flute11. Music Box 75. Recorder12. Vibraphone 76. Pan Flute13. Marimba 77. Blown Bottle14. Xylophone 78. Shakuhachi15. Tubular Bells 79. Whistle16. Dulcimer 80. Ocarina

*Organ* *Synth Lead*17. Drawbar Organ 81. Square Wave18. Percussive Organ 82. Sawtooth Wave19. Rock Organ 83. Calliope20. Church Organ 84. Chiff21. Reed Organ 85. Charang22. Accordion 86. Voice23. Harmonica 87. Fifths24. Tango Accordion 88. Bass and Lead

*Guitar* *Synth Pad*25. Nylon String Guitar 89. New Age26. Steel Acoustic Guitar 90. Warm27. Jazz Electric Guitar 91. Polysynth28. Clean Electric Guitar 92. Choir29. Muted Electric Guitar 93. Bowed30. Overdriven Guitar 94. Metal31. Distortion Guitar 95. Halo32. Guitar harmonics 96. Sweep

*Bass* *Synth Effects*33. Acoustic Bass 97. Rain34. Fingered Electric Bass 98. Soundtrack35. Picked Electric Bass 99. Crystal36. Fretless Bass 100. Atmosphere37. Slap Bass 1 101. Brightness38. Slap Bass 2 102. Goblins39. Synth Bass 1 103. Echoes40. Synth Bass 2 104. Sci-fi

*Strings* *Ethnic*41. Violin 105. Sitar42. Viola 106. Banjo43. Cello 107. Shamisen44. Contrabass 108. Koto45. Tremolo Strings 109. Kalimba47. Pizzicato Strings 110. Bag pipe

47. Orchestral Harp 111. Fiddle48. Timpani 112. Shanai

*Ensemble* *Percussive*49. String Ensemble 1 113. Tinkle Bell50. String Ensemble 2 114. Agogo51. Synth Strings 1 115. Steel Drums52. Synth Strings 2 116. Woodblock53. Choir Aahs 117. Taiko Drum54. Voice Oohs 118. Melodic Tom55. Synth Voice 119. Synth Drum56. Orchestra Hit 120. Reverse Cymbal

*Brass* *Sound Effects*57. Trumpet 121. Guitar Fret Noise58. Trombone 122. Breath Noise59. Tuba 123. Seashore60. Muted Trumpet 124. Bird Tweet61. French Horn 125. Telephone Ring62. Brass Section 126. Helicopter63. Synth Brass 1 127. Applause64. Synth Brass 2 128. Gunshot

NetLogoTableExtension

Using

Thetableextensionispre-installedinNetLogo.

Tousethetableextensioninyourmodel,addalinetothetopofyourCodetab:

extensions [table]

Ifyourmodelalreadyusesotherextensions,thenitalreadyhasanextensionslineinit,sojustaddtabletothelist.


WhentoUse

Ingeneral,anythingyoucandowithantableinNetLogo,youcouldalsojustusealistfor.Butyoumaywanttoconsiderusingantableinsteadforspeedreasons.Listsandtableshavedifferentperformancecharacteristics,soyoumaybeabletomakeyourmodelrunfasterbyselectingtheappropriatedatastructure.

Tablesareusefulwhenyouneedtodoassociatevalueswithothervalues.Forexample,youmightmakeatableofwordsandtheirdefinitions.Thenyoucanlookupthedefinitionofanyword.Here,thewordsarethe"keys".Youcaneasilyretrievethevalueforanykeyinthetable,butnotviceversa.

UnlikeNetLogo’slistsandstrings,tablesare“mutable”.Thatmeansthatyoucanactuallymodifythemdirectly,ratherthanconstructinganalteredcopyaswithlists.Ifthetableisusedinmorethanoneplaceinyourcode,anychangesyoumakewillshowupeverywhere.It’strickytowritecodeinvolvingmutablestructuresandit’seasytomakesubtleerrorsorgetsurprisingresults,sowesuggeststickingwithlistsandstringsunlessyou’recertainyouwantandneedmutability.

Example

let dict table:maketable:put dict "turtle" "cute"table:put dict "bunny" "cutest"print dict=> {{table: "turtle" -> "cute", "bunny" -> "cutest" }}print table:length dict=> 2print table:get dict "turtle"=> "cute"print table:get dict "leopard"=> (error)print table:keys dict=> ["turtle" "bunny"]

ManipulatingTables

Ifthesamekeyisusedwithtable:putmorethanonceforthesametable,thevalueprovidedtolastcalloftable:putwillbethevalueshownwhentable:getisused.Hereisanexample:

let dict table:maketable:put dict "a" 5table:put dict "a" 3print table:get dict "a"=> 3

Becausetablesaremutable,manipulatingexistingvaluesshouldbedonebycallingtable:getortable:get-or-defaultonakey,transformingthereturnedvalue,andthencallingtable:puttoupdatethetransformedvalueinthetable.Hereisanexampleprocedurewhichincrementsavalueinatableatagivenkey.Ifthekeydoesn’texist,itputsa1atthatkeyinstead.

to increment-table-value [ dict key ] let i table:get-or-default dict key 0 table:put dict key i + 1end

KeyRestrictions

TablekeysarelimitedtothefollowingNetLogotypes:

NumbersStringsBooleansListscontainingonlyelementswhicharethemselvesvalidkeys

Ifyouattempttouseanillegalvalue,thetableextensionwillraiseanexception,asshowninthefollowingexample.

crt 1let dict table:maketable:put dict (one-of turtles) 10;; Errors with the following message:;; (turtle 0) is not a valid table key (a table key may only be a number, a string, true or false, or a list whose items are valid keys)

Primitives

table:cleartable:countstable:group-agentstable:group-itemstable:from-listtable:gettable:get-or-defaulttable:has-key?table:keystable:lengthtable:maketable:puttable:removetable:to-listtable:values

table:clear

table:cleartable

Removesallkey-valuepairsfromtable.

table:counts

table:countslist

Countstheoccurrencesofeachelementofthegivenlistandreportsthecountsinatable.

table:group-agents

table:group-agentsagentsetanonymousreporter

Groupstheagentsintheagentsetbasedonthegivenreporter.Agentsthatreportthesamethingforreporterwillbegroupedtogether.Theresultsofthereporterwillbeusedasthekeysintheresultingtableandthegroupswillbeagentsets.

Forexample:

observer> create-turtles 100 [ set color one-of [ red green blue ] ]observer> show table:group-by turtles [ color ]observer: {{table: [[105 (agentset, 38 turtles)] [55 (agentset, 32 turtles)] [15 (agentset, 30 turtles)]]}}

table:group-items

table:group-itemslistanonymous-reporter

Groupstheitemsofthelistbsaedonthegivenreporter.Thereportershouldtakeasingleargument,whichwillbetheitemsofthelist.Itemsthatreportthesamethingwhenpassedtothereporterwillbegroupedtogether.Theresultsofthereporterwillbeusedasthekeysintheresultingtableandthegroupswillbelists.

Forexample:

observer> show table:group-by range 10 [ num -> num mod 3 ]observer: {{table: [[0 [0 3 6 9]] [1 [1 4 7]] [2 [2 5 8]]]}}

table:from-list

table:from-listlist

Reportsanewtablewiththecontentsoflist.listmustbealistoftwoelementlists,orpairs.Thefirstelementinthepairisthekeyandthesecondelementisthevalue.

table:get

table:gettablekey

Reportsthevaluethatkeyismappedtointhetable.Causesanerrorifthereisnoentryforthekey.

table:get-or-default

table:get-or-defaulttablekeydefault-value

Reportsthevaluethatkeyismappedtointhetable.Reportsthedefault-valueifthereisnoentryforthekey.

table:has-key?

table:has-key?tablekey

Reportstrueifkeyhasanentryintable.

table:keys

table:keystable

Reportsalistofallthekeysintable,inthesameorderthekeyswereinserted.

table:length

table:lengthtable

Reportsthenumberofentriesintable.

table:make

table:make

Reportsanew,emptytable.

table:put

table:puttablekeyvalue

Mapskeytovalueintable.Ifanentryalreadyexistsinthetableforthegivenkey,itisreplaced.

table:remove

table:removetablekey

Removesthemappingintableforkey.

table:to-list

table:to-listtable

Reportsalistwiththecontentoftable.Thelistwillbealistoftwoelementlists,orpairs.Thefirstelementinthepairisthekeyandthesecondelementisthevalue.Thekeysappearinthesameordertheywereinserted.

table:values

table:valuestable

Reportsalistwiththeentriesoftable.Theentrieswillappearinthesameordertheywereinserted,withduplicatesincluded.

NetLogoVidExtension

Concepts

VideoSource

Thevidextensionhasabuilt-inconceptofavideosource.Atthemoment,theonlyvideosourcesavailablearemoviesinthedirectorythemodellivesinandcamerasattachedtothecomputer.Thevidextensionopensanewvideosourcewiththevid:<source>-openandvid:<source>-select.Theseprimitiveschangethesourcetotheselectedsource.Ifasourceisalreadyopen,itclosesitbeforeopeninganewone.

SourceLifecycle

Moviesourcesare“stopped”afterbeingcreatedbyvid:movie-selectorvid:movie-open.Camerasourcesstartoffas“playing”afterbeingcreatedbyvid:camera-selectorvid:camera-open.Ifasourceisinstatus“stopped”itcanbestartedwithvid:start.Conversely,ifthesourceis“playing”itcanbestoppedwithvid:stop.Whenasourceis“stopped”,eachcalltovid:capture-imagewillreturnthesameimage.

VideoRecorder

Thevidextensionalsohastheconceptofarecording,aseriesofframeswhichcanbesewnintoan“mp4”movie.Therecorderstatuscanbequeriedusingvid:recorder-status.Therecorderstatusis“inactive”untilstartedwithvid:start-recorder,whichsetsitto“recording”.Whiletherecorderis“recording”thevid:record-view,vid:record-interface,andvid:record-sourcecanbeusedtosaveframestotherecording.Youcanchoosetosavetherecordingwhilerecordingusingvid:save-recordingwhichsavesthemovietothespecifiedfileandresettherecordingstatusto“inactive”.Ifyouwouldprefertothrowawaytherecordedframeswithoutsaving,usevid:reset-recorder.

Primitives

vid:camera-namesvid:camera-openvid:camera-selectvid:movie-selectvid:movie-openvid:movie-open-remotevid:closevid:startvid:stopvid:statusvid:capture-imagevid:set-timevid:show-playervid:hide-playervid:record-viewvid:record-interfacevid:record-sourcevid:recorder-statusvid:start-recordervid:save-recording

vid:camera-names

vid:camera-names

Providesalistofallavailablecameras.

Example:

vid:camera-names => []vid:camera-names => ["Mac Camera"]vid:camera-names => ["Logitech Camera"]

vid:camera-open

vid:camera-open

Opensthenamedcameraasavideosource.Ifnonameisprovided,opensthefirstcamerathat

wouldbelistedbycamera-names.

Example:

vid:camera-open ; opens first camera(vid:camera-open "Logitech Camera")

Errors:

Message"vid: no cameras found" :nocamerasareavailable.Message"vid: camera "\<name\>" not found":ifthenamedcameraisnotavailable.

vid:camera-select

vid:camera-select

Promptstheusertoselectacameraasvideosource.Thiscommanddoesnoterroriftheusercancels.Usevid:statustoseeifauserselectedacamera.

Example:

vid:camera-select

Errors:

Message“vid:nocamerasfound”:nocamerasareavailable.

vid:movie-select

vid:movie-select

Promptstheusertoselectamovietouseasavideosource.TheformatssupportedarethosesupportedbyJavaFX2.Thiscommanddoesnoterroriftheusercancels.Usevid:statustoseeiftheuserselectedamovie.

Example:

vid:movie-select

Errors:

Message"vid: format not supported":theuserselectedamoviewithanunsupportedformat.

vid:movie-open

vid:movie-openfilename

Opensavideofromthefilesystem.Iftheprovidedpathisnotabsolutetheextensionsearchesforthegivenpathrelativetothecurrentmodeldirectory.Iftheprovidedpathisabsolutetheextensionopensthefile.

Example:

vid:movie-open "foo.mp4" ; Opens foo.mp4 in the directory containing the modelvid:movie-open user-file ; Opens a dialog for the user to select a movievid:movie-open "/tmp/foo.mp4" ; Opens a movie from the "/tmp" directory

https://docs.oracle.com/javafx/2/api/javafx/scene/media/package-summary.html#SupportedMediaTypes

Errors:

Message"vid: no movie found" :themoviecouldnotbefound.Message"vid: format not supported":theuserselectedamoviewithanunsupportedformat.

vid:movie-open-remote

vid:movie-open-remoteurl

Opensaremotevideofromawebsiteorftpserver.

Example:

vid:movie-open-remote "http://example.org/foo.mp4"

Errors:

Message"vid: no movie found" :ThespecifiedURLcouldnotbeloadedorerroredwhileloading.Message"vid: format not supported":Thefiletypeoftheremotemovieisnotsupported.Message"vid: protocol not supported":ThemoviewasatanunsupportedURLprotocol.Supportedprotocolsareftpandhttp.

vid:close

vid:close

Closesthecurrentlyselectedvideosource.Hasnoeffectifthereisnoactivevideosource.

Example:

vid:close

vid:start

vid:start

Startstheselectedvideosource.Avideosourcemusthavebeenselectedbeforecallingvid:start.

Example:

vid:start

Errors:

Message"vid: no selected source":Thereisnocurrentlyselectedvideosource.Selectasourcewithvid:movie-open,vid:movie-select,vid:camera-open,orvid:camera-select.

vid:stop

vid:stop

Stopsthecurrentlyrunningvideosource.

Example:

vid:stop

vid:status

vid:status

Reportsthecurrentstatusofanactivevideo.Notethataftercallingvid:movie-openorvid:movie-selectthestatuswillbesetto“stopped”,whileaftercallingvid:camera-openorvid:camera-selectthestatuswillbe“playing”.

Example:

vid:status ; => "inactive"

vid:movie-open "foobar.mp4"vid:status ; => "stopped"

vid:movie-startvid:status ; => "playing"

vid:capture-image

vid:capture-imagewidthheight

Capturesanimagefromthecurrentlyselectedactivesource.

Ifwidthandheightarenotspecified,theimageiscapturedatthecurrentsourceresolution.

Example:

extensions [ vid bitmap ]

to capture ; capture an image if a video source is open, ; have the user select a camera if no video source found carefully [ ; when camera open, take an image let image vid:capture-image ; returns image suitable for use with bitmap extension bitmap:copy-to-drawing image 0 0 ] [ if error-message = "Extension exception: vid: no selected source" [ vid:camera-select vid:start let image vid:capture-image bitmap:copy-to-drawing image 0 0 ] ]end

Ifyouwanttocaptureimagesatadifferentresolution,simplyreplacevid:capture-imagewith,e.g.,(vid:capture-image 640 480).

Errors:

Message"vid: no selected source":Thereisnocurrentlyselectedvideosource.Selectasourcewithvid:movie-open,vid:movie-select,vid:camera-open,orvid:camera-select.Message"vid: invalid dimensions":Theselecteddimensionsareinvalid(oneofthedimensionsiszeroornegative).

vid:set-time

vid:set-timeseconds

Setsthetimeofthecurrentvideosourceto*seconds*.Thishasnoeffectwhenthecurrentvideosourceisacamera.

Example:

vid:set-time 100

Errors:

Message"vid: no selected source":Thereisnocurrentlyselectedvideosource.Selectasourcewithvid:movie-open,vid:movie-select,vid:camera-open,orvid:camera-select.Message"vid: invalid time":Thecurrentlyactivevideodoesnotcontainthespecifiedsecond.Thesecondmaybenegative,orgreaterthanthelengthofthevideo.

vid:show-player

vid:show-playerwidthheight

Showsaplayerinaseparatewindow.Ifthereisnovideosource,thewindowwillbeanemptyblackframe.Ifthereisanactivevideosource,itwillbedisplayedinthewindowwiththespecifiedwidthandheight.Ifthereisaplayingvideosource,itwillbedisplayedinthewindowatitsspecifiedwidthandheight.Ifwidthandheightareomitted,thevideowillbedisplayedinitsnativeresolution.

Examplewithnativeresolution:

vid:show-player

Examplewithcustomresolution:

(vid:show-player 640 480)

Errors:

Message"vid: invalid dimensions":Theselecteddimensionsareinvalid(oneofthedimensionsiszeroornegative).

vid:hide-player

vid:hide-player

Hidestheplayerifopen.Doesnothingifthereisnoplayerwindow.

Example:

vid:hide-player

vid:record-view

vid:record-view

RecordsthecurrentimageshownintheNetLogoviewtotheactiverecording.

Example:

vid:record-view

Errors:

Message"vid: recorder not started":Therecorderhasnotbeenstarted.Starttherecorderwithvid:start-recorder.

vid:record-interface


RecordstheNetLogointerfaceviewtotheactiverecording.

Example:


Errors:

Message"vid: recorder not started":Therecorderhasnotbeenstarted.Starttherecorderwithvid:start-recorder.Message"vid: export interface not supported":ThecallingNetLogoversiondoesnotsupportinterfaceexports.ThiswilloccurwhenrunningNetLogoheadlessly.

vid:record-source

vid:record-source

Recordsaframetotheactiverecordingfromthecurrentlyactivesource.

Example:

vid:record-source

Errors:

Message"vid: recorder not started":Therecorderhasnotbeenstarted.Starttherecorderwithvid:start-recorder.Message"vid: no selected source":Thereisnocurrentlyselectedvideosource.Selectasourcewithvid:movie-open,vid:movie-select,vid:camera-open,orvid:camera-select.

vid:recorder-status

vid:recorder-status

Reportsthecurrentstatusoftherecorder.Initiallyandaftertherecorderissaved(viavid:save-recording)orreset(viavid:reset-recorder)therecorderstatusis“inactive”.Aftercallingvid:start-recorderthestatuswillbe“recording”.

Example:

vid:recorder-status ; => "inactive"

vid:start-recordervid:recorder-status ; => "recording"

vid:reset-recordervid:recorder-status ; => "inactive"

vid:start-recorder

vid:start-recorder

Startstherecorder.Iftherecorderisalreadyrunningthiswillcauseanerrortoberaised.Ifdesired,arecordingwidthandheightcanbesupplied.Ifwidthandheightarenotsupplied,theywillbedeterminedfromthefirstframerecorded.

Example:

vid:start-recorder(vid:start-recorder 640 480)

Errors:

Message"vid: recorder already started":Therecorderhasalreadybeenstarted.Theexistingrecordingshouldbesavedorresetbeforestartingtherecording.Message"vid: invalid dimensions":Theselecteddimensionsareinvalid(oneofthedimensionsiszeroornegative).

vid:save-recording

vid:save-recordingfilename

Savestherecordingtothespecifiedpath.Iftherecorderisnotrunningthiswillcauseanerrortoberaised.Notethatatpresenttherecordingwillalwaysbesavedinthe“mp4”format.Ifthesuppliedfilenamedoesnotendin“.mp4”,the“.mp4”suffixwillbeadded.Notethatvid:save-recordingwilloverwriteexistingfilesofthesamename.vid:save-recordingwillerroriftherecorderhasnotbeenstartedorifthefilecannotbewrittensincethecontainingdirectorydoesnotexist.

Example:

vid:save-recording "foo.mp4" ; Saves to foo.mp4 in the directory containing the modelvid:save-recording user-new-file ; Opens a dialog for the user to select a save pathvid:save-recording "/tmp/foo.mp4" ; Saves the recording to the "/tmp" directory

Errors:

Message"vid: recorder not started":Therecorderhasnotbeenstarted.Starttherecorderwithvid:start-recorder.Message"vid: no such directory":Thedirectorycontainingthespecifiedsavefiledoesnotexist.Message"vid: no frames recorded":Youtriedtosavearecordingwithnoframesrecorded.Checkthatyouarerecordingproperlyorusevid:reset-recordingtotochangetherecordingformatwithoutsaving.

NetLogoView2.5dExtension

TheView2.5DextensionoffersvisualizationforPatchandTurtlereporters,inrealtime,inasimulation’scontext.

HowtoUse

Theview2.5dextensionispre-installedinNetLogo.

Tousetheview2.5dextensioninyourmodel,addalinetothetopofyourCodetab:

extensions [view2.5d]

Ifyourmodelalreadyusesotherextensions,thenitalreadyhasanextensionslineinit,sojustaddview2.5dtothelist.


IncorporatingIntoModels

openawindowusingeithertheview2.5d:patch-vieworview2.5d:turtle-viewcommands(itcanbeagoodideatoputtheseinyour‘SETUP’procedureoraseparatebutton).

updateyourwindow’sviewusingoneoftheupdatecommands(puttheseinyour‘GO’procedure).

SeetheView2.5dCodeExamplesintheNetLogomodelslibrary.

Feedback

Sendcomments,bugs,orotherfeedbacktoCCLFeedbackand/orCoreyBrady.

Primitives

view2.5d:patch-viewview2.5d:decorate-patch-viewview2.5d:undecorate-patch-viewview2.5d:turtle-viewview2.5d:update-all-patch-viewsview2.5d:update-patch-viewview2.5d:update-turtle-viewview2.5d:get-z-scaleview2.5d:set-z-scaleview2.5d:set-turtle-stem-thicknessview2.5d:get-observer-anglesview2.5d:set-observer-anglesview2.5d:get-observer-xy-focusview2.5d:set-observer-xy-focusview2.5d:get-observer-distanceview2.5d:set-observer-distanceview2.5d:remove-patch-viewview2.5d:remove-turtle-viewview2.5d:remove-all-patch-viewsview2.5d:remove-all-turtle-viewsview2.5d:count-windows

view2.5d:patch-view

view2.5d:patch-viewTitleReporter

ThiscommandmustbecalledfromtheObservercontext.(Attemptingtocallfromanothercontextcausesanerror)TheTitleisastring,whichwillbeusedtolabelthenewWindowandtocallforsubsequentupdatesandmodifications.SpecificationoftheReporterusestheNetLogoanonymousproceduresyntax,fromtheObserverperspective.

Example:

view2.5d:patch-view "Test" [ [the-turtle] -> [pxcor] of the-turtle]

view2.5d:decorate-patch-view

view2.5d:decorate-patch-viewTitle



ThiscommandmustbecalledfromtheObservercontext.(Attemptingtocallfromanothercontextcausesanerror)TheTitleisastring,thelabelofanexistingPatchViewWindow.Effect:drawstheturtlesofthemodelattheircurrentlocation,ontopofthePatchviewdisplay

NOTE:onlyhasaneffectinthe“structures”patchview(intheothers,thepatchvalueisinclinedbasedonneighbors&gradient)

NOTE:fornegativepatchvalues,theturtleshapesaredrawnbelow(orbitunderneathtoseethem)

Example:

view2.5d:decorate-patch-view "Test"

view2.5d:undecorate-patch-view

view2.5d:undecorate-patch-viewTitle

ThiscommandmustbecalledfromtheObservercontext.(Attemptingtocallfromanothercontextcausesanerror)

TheTitleisastring,thelabelofanexistingPatchViewWindow.Effect:STOPSdrawingtheturtlesofthemodelattheircurrentlocation,ontopofthePatchviewdisplay

Example:

view2.5d:undecorate-patch-view "Test"

view2.5d:turtle-view

view2.5d:turtle-viewTitleAgentsReporter

ThiscommandmustbecalledfromtheObservercontext.(Attemptingtocallfromanothercontextcausesanerror)TheTitleisastring,whichwillbeusedtolabelthenewWindowandtocallforsubsequentupdates.Theturtle-setisanyselectorforturtles.SpecificationoftheReporterusestheNetLogotasksyntax,fromtheObserverperspective.

Example:

view2.5d:turtle-view "Test" turtles with [color = red] [[energy] of ?1]; This would create a new 2.5d window, plotting the ENERGY value of all turtles that are red.

view2.5d:update-all-patch-views

view2.5d:update-all-patch-views

ThiscommandmustbecalledfromtheObservercontext.Updatesallexistingpatch-viewwindowsaccordingtothelatestvalues.

view2.5d:update-patch-view

view2.5d:update-patch-viewTitle

ThiscommandmustbecalledfromtheObservercontext.Updatesonlythepatch-viewwindowwiththespecifiedtitle(ifany).

view2.5d:update-turtle-view

view2.5d:update-turtle-viewTitleAgents

ThiscommandmustbecalledfromtheObservercontext.Updatesonlytheturtle-viewwindowwiththespecifiedtitle(ifany).Theturtle-setselectormustbesuppliedtorefreshthesetofturtles.

view2.5d:get-z-scale

view2.5d:get-z-scaletitle

ThisreportermustbecalledfromtheObservercontext.Returnsthecurrentz-scaleoftheturtle-vieworpatch-viewwindowwiththespecifiedtitle(ifany).

view2.5d:set-z-scale

view2.5d:set-z-scaleTitlenew-z-scale

ThiscommandmustbecalledfromtheObservercontext.Updatesonlytheturtle-vieworpatch-viewwindowwiththespecifiedtitle(ifany).Theviewisnowdisplayedwiththenewz-scale.

view2.5d:set-turtle-stem-thickness

view2.5d:set-turtle-stem-thicknessTitlethickness

ThiscommandmustbecalledfromtheObservercontext.Updatesonlytheturtle-viewwindowwiththespecifiedtitle(ifany).Turtlesarenowdrawnwith“pins”or“stems”thathavethespecifiedthickness(insteadofthehairlinedefault)

view2.5d:get-observer-angles

view2.5d:get-observer-anglesTitle

ThisreportermustbecalledfromtheObservercontext.Returnsalistreflectingtheobserver’sangularperspective{headingpitch}(theplaceonanimaginarysphereatthezoomdistanceisupdatedtoobeyheading&pitchgiven)

view2.5d:set-observer-angles

view2.5d:set-observer-anglesTitleheadingpitch

ThiscommandmustbecalledfromtheObservercontext.Updatesonlytheturtle-viewwindowwiththespecifiedtitle(ifany).Setstheobserver’sangularperspective(theplaceonanimaginarysphereatthezoomdistanceisupdatedtoobeyheading&pitchgiven)

view2.5d:get-observer-xy-focus

view2.5d:get-observer-xy-focusTitle

ThisreportermustbecalledfromtheObservercontext.Returnsalistreflectingthexandycoordinatestheobserveris“lookingat”inthepatchplane.

view2.5d:set-observer-xy-focus

view2.5d:set-observer-xy-focusTitlenumberycor

ThiscommandmustbecalledfromtheObservercontext.Updatesonlytheturtle-viewwindowwiththespecifiedtitle(ifany).Setsthexandycoordinatestheobserverthatis“lookingat”inthepatchplane.

view2.5d:get-observer-distance

view2.5d:get-observer-distanceTitle

ThisreportermustbecalledfromtheObservercontext.Returnstheobserver’sdistancefromits“focuspoint”

view2.5d:set-observer-distance

view2.5d:set-observer-distanceTitlenew-distance

ThiscommandmustbecalledfromtheObservercontext.Updatesonlytheturtle-viewwindowwiththespecifiedtitle(ifany).Setstheobserver’sdistancefromits“focuspoint”

view2.5d:remove-patch-view

view2.5d:remove-patch-viewTitle

Thiscommandclosesandremovesthespecifiedpatchviewprogrammatically(equivalenttoclosingthewindowmanually).

view2.5d:remove-turtle-view

view2.5d:remove-turtle-viewTitle

Thiscommandclosesandremovesthespecifiedturtleviewprogrammatically(equivalenttoclosingthewindowmanually).

view2.5d:remove-all-patch-views

view2.5d:remove-all-patch-views

Thiscommandclosesandremovesallpatchviewsprogrammatically(equivalenttoclosingthewindowsmanually).

view2.5d:remove-all-turtle-views

view2.5d:remove-all-turtle-views

Thiscommandclosesandremovesallturtleviewsprogrammatically(equivalenttoclosingthewindowsmanually).

view2.5d:count-windows

view2.5d:count-windows

Thisreporterreturnsthenumberofturtleandpatchviewsthatarecurrentlyactive.

FAQ(FrequentlyAskedQuestions)

FeedbackfromusersisveryvaluabletousindesigningandimprovingNetLogo.We'dliketohearfromyou.(SeeContactingUs.)

Questions

General

WhyisitcalledNetLogo?HowdoIciteNetLogoorHubNetinapublication?HowdoIciteamodelfromtheModelsLibraryinapublication?WhereandwhenwasNetLogocreated?WhatprogramminglanguagewasNetLogowrittenin?What'sthedifferencebetweenStarLogoandNetLogo?UnderwhatlicenseisNetLogoreleased?Isthesourcecodeavailable?DoyouofferanyworkshopsorothertrainingopportunitiesforNetLogo?ArethereanyNetLogotextbooks?IsNetLogoavailableinotherlanguagesbesidesEnglish?IsNetLogocompiledorinterpreted?Hasanyonebuiltamodelof<x>?AreNetLogomodelsrunsscientificallyreproducible?WillNetLogoandNetLogo3Dremainseparateapplications?CanIrunNetLogoonmytabletorphone?

Downloading

CanIhavemultipleversionsofNetLogoinstalledatthesametime?I'monaUNIXsystemandIcan'tuntarthedownload.Why?HowdoIinstallNetLogounattended?

Running

CanIrunNetLogofromaCD,anetworkdrive,oraUSBdrive?WhyisNetLogosomuchslowerwhenIunplugmyWindowslaptop?WhydoesNetLogobundleJava?HowcomeNetLogowon'tstartuponmyLinuxmachine?WhenItrytoinstallNetLogoonWindows,Isee"WindowsprotectedyourPC"WhenItrytostartNetLogoonWindowsIgetanerror"TheJVMcouldnotbestarted".Help!NetLogowon'tstartonMacOSSierra(orlater)NetLogowon'tstartonWindowsorcrashessuddenlyonMacOSSierraCanIrunNetLogofromthecommandline,withouttheGUI?DoesNetLogotakeadvantageofmultipleprocessors/cores?CanIdistributeNetLogomodelrunsacrossaclusterorgridofcomputers?IsthereanywaytorecoverlostworkifNetLogocrashesorfreezes?

Usage

WhenImovethespeedsliderallthewaytotheright,whydoesmymodelseemtostop?CanIusethemouseto"paint"intheview?Howbigcanmymodelbe?Howmanyturtles,patches,procedures,buttons,andsooncanmymodelcontain?CanIuseGISdatainNetLogo?Mymodelrunsslowly.HowcanIspeeditup?CanIhavemorethanonemodelopenatatime?CanIchangethechoicesinachooseronthefly?CanIdividethecodeformymodelupintoseveralfiles?

Programming

HowdoestheNetLogolanguagedifferfromotherLogos?HowcomemymodelfromanearlierNetLogodoesn'tworkright?HowdoItakethenegativeofanumber?Myturtlemovedforward1,butit'sstillonthesamepatch.Why?HowdoIkeepmyturtlesonpatchcenters?patch-ahead 1isreportingthesamepatchmyturtleisalreadystandingon.Why?HowdoIgivemyturtles"vision"?Canagentssensewhat'sinthedrawinglayer?I'mgettingnumberslike0.10000000004and0.799999999999insteadof0.1and0.8.Why?Thedocumentationsaysthatrandom-float 1.0mightreturn0.0butwillneverreturn1.0.WhatifIwant1.0tobeincluded?HowcanIusedifferentpatch"neighborhoods"(circular,VonNeumann,Moore,etc.)?HowcanIkeeptwoturtlesfromoccupyingthesamepatch?HowcanIfindoutifaturtleisdead?DoesNetLogohavearrays?DoesNetLogohavehashtablesorassociativearrays?HowcanIconvertanagentsettoalist,orviceversa?HowdoIstopforeach?I'mtryingtomakealist.WhydoIkeepgettingtheerror"Expectedaconstant"?

BehaviorSpace

WhyaretherowsinmyBehaviorSpacetableresultsoutoforder?HowdoIgatherdataeverynticks?I'mvaryingaglobalvariableIdeclaredintheCodetab,butitdoesn'twork.Why?

NetLogo3D

DoesNetLogo3Dworkwithmystereoscopicdevice?

Extensions

I'mwritinganextension.Whydoesthecompilersayitcan'tfindorg.nlogo.api?

General

WhyisitcalledNetLogo?

The"Logo"partisbecauseNetLogoisadialectoftheLogolanguage.

"Net"ismeanttoevokethedecentralized,interconnectednatureofthephenomenayoucanmodelwithNetLogo,includingnetworkphenomena.ItalsoreferstoHubNet,themultiuserparticipatorysimulationenvironmentincludedinNetLogo.

HowdoIciteNetLogoorHubNetinapublication?

IfyouuseorrefertoNetLogo,HubNetoramodelfromtheNetLogomodelslibrary,weaskthatyouciteitasfollows:

NetLogoitself:Wilensky,U.1999.NetLogo.http://ccl.northwestern.edu/netlogo/.CenterforConnectedLearningandComputer-BasedModeling,NorthwesternUniversity.Evanston,IL.


HubNet:Wilensky,U.&Stroup,W.,1999.HubNet.http://ccl.northwestern.edu/netlogo/hubnet.html.CenterforConnectedLearningandComputer-BasedModeling,NorthwesternUniversity.Evanston,IL.

HowdoIciteamodelfromtheModelsLibraryinapublication?

Thecorrectcitationisincludedinthe"CreditsandReferences"sectionofeachmodel'sInfotab.

WhereandwhenwasNetLogocreated?

NetLogowasfirstcreatedin1999byUriWilenskyattheCenterforConnectedLearningandComputer-BasedModeling,thenatTuftsUniversityintheBostonarea.NetLogogrewoutofStarLogoT,whichwasauthoredbyWilenskyin1997.In2000,theCCLmovedtoNorthwesternUniversity,intheChicagoarea.NetLogo1.0cameoutin2002,2.0in2003,3.0in2005,4.0in2007,4.1in2009,and5.0in2012.

WhatprogramminglanguagewasNetLogowrittenin?

NetLogoiswrittenmostlyinScala,withsomepartsinJava.(ScalacodecompilestoJavabytecodeandisfullyinteroperablewithJavaandotherJVMlanguages.)

What'stherelationshipbetweenStarLogoandNetLogo?

TheoriginalStarLogobeganattheMITMediaLabin1989andranontheConnectionMachine.LaterversionsweredevelopedforMacintoshcomputers:MacStarLogo(1994,MIT)andStarLogoT(1997,Tufts).

TodaytherearetwoStarLogodescendantsunderactivedevelopment:NetLogo(fromtheCCLatNorthwesternUniversity)andStarLogoTNG(fromMIT).NetLogoisthemostwidelyusedagent-basedmodelingenvironmentinbotheducationandresearch.StarLogoTNGisdistinguishedbyitsprogramminginterfacebasedoncoloredblocks.

UnderwhatlicenseisNetLogoreleased?Isthesourcecodeavailable?

NetLogoisfree,opensourcesoftwareundertheGPL(GNUGeneralPublicLicense),version2,or(atyouroption)anylaterversion.

Commerciallicensesarealsoavailable.Toinquireaboutcommerciallicenses,[email protected].

ThesourcecodeisonGitHub,here.Developmentdiscussionisonthenetlogo-develgroup.

TheUserManualispublishedunderaCreativeCommonsAttribution-ShareAlikelicense(CCBY-SA3.0).

SourcecodeforalloftheextensionsbundledwithNetLogoisonGitHub,here.Mostoftheextensionsareinthepublicdomain(CC0notice).Otherextensionsarereleasedunderopensourcelicenses.Seeeachextension'sREADMEfordetails.

TheCodeExamplesintheModelsLibraryareinthepublicdomain(CC0notice).

http://ccl.northwestern.edu/netlogo/hubnet.html

http://www.gnu.org/licenses/gpl-2.0.html



http://groups.google.com/group/netlogo-devel


https://github.com/NetLogo/

http://creativecommons.org/about/cc0

http://creativecommons.org/about/cc0

TherestofthemodelsintheModelsLibraryareprovidedunderavarietyoflicenses.Somearepublicdomainandsomeareopensource,butmostareundertheCreativeCommonsAttribution-ShareAlikelicense(CCBY-NC-SA),whichisnotanopensourcelicense,thoughthemodelsarefreefornoncommercialdistributionanduse.

Seeeachmodel'sInfotabtocheckitsparticularlicense.

ThemodelsareinapublicGitrepositoryhere.

DoyouofferanyworkshopsorothertrainingopportunitiesforNetLogo?

Weofferworkshopsfromtimetotime.Ifaworkshophasbeenscheduled,wewillannounceitontheNetLogoUsersGroup.

ArethereanyNetLogotextbooks?

TheCCLhaspublishedatextbook(writtenbytheauthorofNetLogo)thatgivesanintroductiontoagent-basedmodelingmethodsusingNetLogo.Itgoesstepbystepwithcodingexampleshowtodesign,build,revise,andanalyzemodels.Anditpresentssomeadvancedtechniques.

Seewww.intro-to-abm.comformoreinformationonthattextbook.

SeetheTextbookssectionofourResourcespage.

WeattheCCLhavehopedtowriteseveralmoreNetLogotextbooks.Thesecouldbeaimedatdifferentaudiences,suchas:middleschool,highschool,undergraduatecourseinmodelingorcomplexity,practicalguideforinterestedadults.

Unfortunately,wehavenotyetbeenabletofindthetimetomakethesehappen.Ifanyonefromtheusercommunitywouldliketocollaborateonsuchaventure,pleaseletusknow.Wewouldwelcomeit.

IsNetLogoavailableinotherlanguagesbesidesEnglish?

VolunteershavetranslatedtheusermanualintoChineseandCzech.ThetranslatedversionsareavailablefromtheNetLogowebsite.

Sofar,theNetLogouserinterfacehasbeenlocalizedinEnglish,Spanish,Chinese,Russian,andJapanese.Allfivelanguagesareincludedinthestandarddownload.

WeareseekingvolunteerstocompleteandimprovetheselocalizationsandtotranslatetheNetLogosoftwareandmanualintoasmanyotherlanguagesaspossible.Ifyou'reabletohelpinthisendeavor,pleasecontactus.

IsNetLogocompiledorinterpreted?

Shortanswer:someofboth.

Longanswer:NetLogodoesincludeacompilerthatgeneratesJavabytecode.However,thiscompilerdoesnotyetsupporttheentirelanguage,sosomepartsofusercoderemaininterpreted.NotethatourcompilergeneratesJavabytecode,andJavavirtualmachineshave

http://creativecommons.org/licenses/by-nc-sa/3.0/

https://github.com/NetLogo/models


http://www.intro-to-abm.com

http://ccl.northwestern.edu/netlogo/resources.shtml

"just-in-time"compilersthatinturncompileJavabytecodeallthewaytonativecode,somuchusercodeisultimatelytranslatedtonativecode.

Hasanyonebuiltamodelof<x>?

TrylookingattheNetLogoModelsLibrary,theNetLogoModelingCommons,ourCommunityModelspage,andourlistofreferencestoNetLogoinoutsideworks.

YoumightalsoaskthequestionontheNetLogoUsersGroupand/orsearchpastmessagesonthegroup.

AreNetLogomodelsrunsscientificallyreproducible?

Yes.NetLogo'spseudorandomnumbergeneratorandagentschedulingalgorithmsaredeterministic,andNetLogoalwaysusesJava's"strictmath"library,whichgivesbit-for-bitidenticalresultsregardlessofplatform.Butkeepthefollowingcautionsinmind:

Ifyourmodelusesrandomnumbers,theninordertogetreproduciblebehavior,youmustusetherandom-seedcommandtosettherandomseedinadvance,sothatyourmodelwillreceivetheexactsamesequenceofrandomnumberseverytime.Rememberthatagentsetsarealwaysinrandomorder,soanythingyoudowithagentsetsusesrandomnumbers.Ifyourmodelusestheeveryorwaitcommandsinsuchawaythataffectstheoutcomeofthemodel,thenyoumaygetdifferentresultsondifferentcomputers,orevenonthesamecomputer,sincethemodelmayrunatadifferentspeed.Inordertoreproducemodelrunsexactly,youmustbeusingtheexactsameversionofNetLogo.ThedetailsoftheagentschedulingmechanismandtherandomnumbergeneratormaychangebetweenNetLogoversions,andotherchanges(bugfixesintheengine,languagechanges,andsoforth)mayalsoaffectthebehaviorofyourmodel.(Thenagain,theymaynot.)WehaveexpendedeveryefforttomakeNetLogomodelrunsfullyreproducible,butofcoursethiscannevertrulybeaniron-cladguarantee,duenotonlytothepossibilityofrandomhardwarefailure,butalsothepossibilityofhumanerrorinthedesignof:yourmodel,NetLogo,yourJavaVM,yourhardware,andsoon.

WillNetLogoandNetLogo3Dremainseparate?

Fornow,yes.NetLogo3DisincludedwithNetLogo,butitisstillaseparateapplication.

Ideallyasingleunifiedapplicationwouldsupportboth2Dand3Dmodeling.Wewoulddesignthe3Dworldsupportsoitdoesn'tgetinthewaywhenyouarebuilding2Dmodels.ModelsbuiltinNetLogo3Dmightrequirechangesinordertoruninthehypotheticalunifiedapplication.

CanIrunNetLogoonmyphoneortablet?

No.NeitheriOS,norAndroid,norWindowsRTsupportsrunningJavaapplicationssuchasNetLogo.

WeareworkingonanalternateimplementationofNetLogoonaJavaScriptandHTML5base,insteadofJava.Itwillworkonavarietyoftabletsandphones.Wedon'tknowyetwhenitwillbeready,andweexpectthatforalongtimeitwillonlysupportasubsetofthefeaturesindesktopNetLogo.Themanyperson-yearsofdevelopmenteffortthathavegoneintothe

http://ccl.northwestern.edu/netlogo/models/


http://ccl.northwestern.edu/netlogo/models/community/

http://ccl.northwestern.edu/netlogo/references.shtml

Javaversioncan'tcheaplyoreasilybereplicatedonanotherplatform.

Fortechnicaldetailsonthisnewproject,gohere.

Downloading

CanIhavemultipleversionsofNetLogoinstalledatthesametime?

Yes.WhenyouinstallNetLogo,thefolderthatiscreatedcontainshastheversionnumberinitsname,somultipleversionscancoexist.

OnWindowssystems,whicheverversionyouinstalledlastwillbetheversionthatopenswhenyoudoubleclickamodelfileinWindowsExplorer.OnMacs,youcancontrolwhatversionopensvia"GetInfo"intheFinder.

I'monaUNIXsystemandIcan'tuntarthedownload.Why?

Someofthefilesinthetarballhavelongpathnames,toolongforthestandardtarformat.YoumustusetheGNUversionoftarinstead(oranotherprogramwhichunderstandstheGNUtarextensions).Onsomesystems,theGNUversionoftarisavailableunderthename"gnutar".YoucanfindoutifyouarealreadyusingtheGNUversionbytypingtar --versionandseeingiftheoutputsays"tar(GNUtar)".

HowdoIinstallNetLogounattended

Itdependsonwhichplatformyouareusing.

Linux:UntarNetLogointotheappropriateplace.

Mac:CopytheNetLogodirectoryfromthediskimageintotheApplicationsfolder.

Windows:

Runtheinstallerfromthecommandlineusingthe-qoption:

NetLogo6.0.2Installer.exe -q

Running

CanIrunNetLogofromaCD,anetworkdrive,oraUSBdrive?

Yes.NetLogorunsfinefromanyfilesystem,includingread-onlyfilesystems.

WhyisNetLogosomuchslowerwhenIunplugmyWindowslaptop?

Yourcomputerisswitchingtopowersavingmodewhenunplugged.It'snormalforthistoreducespeedalittle,butunfortunatelythereisabuginJavathatdrasticallyslowsdownSwingapplications,includingNetLogo.

Oneworkaroundistochangethepowersettingsonyourcomputersoitdoesn'tgointopower

https://github.com/NetLogo/NetLogo/wiki/Tortoise

savingmodewhenyouunplugit.(Ifyoudothis,yourbatterywon'tlastaslong.)

AnotherworkaroundistorunNetLogowithanoptionrecommendedbyOracle,byeditingtheNetLogo6.0.2.vmoptionsfile,foundintheNetLogodirectory(underProgramFilesonyourharddrive,unlessyouinstalledNetLogoinadifferentlocation).Addonanewline:

-Dsun.java2d.ddoffscreen=false

YoucanseethedetailsoftheJavabugandvoteforOracletofixithere.

WhydoesNetLogobundleJava?

SinceMacOSXLion,ApplehaveencouragedMacapplicationdeveloperstobundleJava.NetLogobundlesJavabecauseitallowsustodeliveraconsistent,convenientexperiencetoourusers.BundlingJavaallowsustotestforcompatibilityonceandavoidanybugscausedbyversionmismatchesorJavaconfigurationincompatibilities.

IfusersareinterestedinusingJavaontheirsysteminsteadoftheversionofJavabundledwithNetLogo,theycanconfigureNetLogotouseadifferentJavaruntime.Pleasenotethatthischangeisdoneatyourownrisk.WeareunabletooffersupportforproblemscausedbyrunningNetLogowithanalternateJavaRuntime.TochangetheJavaruntimeusedbyNetLogo,opentheNetLogo.cfgfileandmodifytheapp.runtimepropertytothepathofyourpreferredJavaRuntime.

HowcomeNetLogowon'tstartuponmyLinuxmachine?

WebundleOracle'sJavaruntimewhenusingNetLogoonLinux.Ifyouwouldliketochangetheversionoflinuxused,youcanmodifythe.cfgfilestopointtoadifferentversionofjava(seeHowbigcanmymodelbe?formoreinformation).

Intheory,anyJava8orlaterruntimewillrunNetLogo.Inpractice,someJavaimplementationsaren'thighenoughquality.RecentversionsofOpenJDKshouldwork;olderonesmaynot.GNUlibgcjdoesnotwork.

Ubuntuusersshouldconsulthttp://help.ubuntu.com/community/Java.

WhenItrytoinstallNetLogoonWindows,Isee"WindowsprotectedyourPC"

Windowsattemptstoprotectusersfromdownloadingmalicioussoftwarebymaintainingalistof"good"and"malicious"software.ThefirstuserstoinstallanyNetLogoreleasewillseethiswarning.Laterusersmayormaynotseethiswarning.Beforegoinganyfurther,ensureyouareprotected.TheCCLcanonlyvouchforNetLogodownloadshostedontheCCLWebsite.NetLogocanbefreelydownloadedfromtheofficialNetLogodownloadpage.IfyouobtainNetLogofromanywhereelse,youinstallitatyourownrisk!

YoucancontinuepasttheWindowspromptbytakingthefollowingsteps:

Inthe"WindowsprotectedyourPC"prompt,click"MoreInfo",thepromptwillchangeInthechangedprompt,click"RunAnyway"andcontinuewithinstallationasnormal

Noteinordertoseethe"MoreInfo"or"RunAnyway"options,youwillneedtoruntheinstallerasanadministrator.Ifyoudonotseethoseoptions,right-clickandchoose"Runas

http://bugs.sun.com/bugdatabase/view_bug.do?bug_id

http://help.ubuntu.com/community/Java

http://ccl.northwestern.edu/netlogo/download.shtml

administrator"and/orchangeyouruseraccounttoanadministratoraccountbeforeinstalling.

WeattheCCLareworkingonsolvingthisproblemandhopetofreeourusersoftheaddedinstallationdifficultysoon!

WhenItrytostartNetLogoonWindowsIgetanerror"TheJVMcouldnotbestarted".Help!

AnearlycertainfixistouseatexteditortoedittheNetLogo.cfgfile,changing1024mtoasmallernumber,like512m.ThisshouldpermitNetLogotostart,althoughthelowerheapsizelimitmayaffectyourabilitytorunmodelswithmanyagents.SeeHowbigcanmymodelbe?forinformationonmodelsizeandhowtoeditthecfgfile.

Ifrunningwiththelowerheapsizelimitisunacceptable,readon.

SomeWindowssystemshavetroubleallocatinglargeamountsofcontiguousvirtualmemory.UpgradingtoanewerversionofWindowsmayhelp.

RunningWindowsin64-bitmodeinsteadof32-bitmodemayalsohelp.DoublecheckthatWindowsisactuallyrunningin64-bitmode;seeMicrosoft'sFAQpageon64-bitWindows.

NetLogowon'tstartonMacOSSierra(orlater)

SomeusershavereportedproblemsopeningNetLogo6onMacOSSierra.We'vebeenunabletodeterminearootcauseforthisproblem,butwe'recontinuingtoinvestigate.We'relookingforassistancefromyouifyourunintothisproblem.Itwouldbeextremelyhelpfulifyoucouldrunthefollowingcommandinthe"Terminal"[email protected].

xattr -pl com.apple.quarantine /Applications/NetLogo\ 6.0/NetLogo\ 6.0.app

runningitshouldgiveyouasinglelineofoutput(somethinglikecom.apple.quarantine:01e1;58ac6af2;Firefox;F2E0B1E2-D203-4B05-8DF9-ABA58B52EFEA,butyourswillhavedifferentnumbers,letters,andwords).Pleasecopyandpastethisstringintotheemailyousendus.

Thereisalsoapartialworkaround!RunningthefollowingcommandintheTerminalwillenableuserstorunNetLogowithoutturningGatekeepercompletelyoff.Thecommandis:

sudo xattr -dr com.apple.quarantine /Applications/NetLogo\ 6.0/NetLogo\ 6.0.app

NotethatifyouplantorunNetLogo3D,HubNetClient,orNetLogoLogging,youmayalsoneedtore-runthatcommandonceforeachofthoseapplications.Iftheworkaroundwasnoteffectiveforyou,pleasesendusanemailandletusknow.

NetLogowon'tstartonWindowsorcrashessuddenlyonMacOSSierra

SomeusersonMacOSwithdiscretegraphicscardsexperiencesuddencrashesofNetLogowhenswitchingbetweenintegratedanddiscretegraphics.It'spossibletopreventthesecrashesbydisablingautomaticgraphicsswitchinginSystemPreferences.

SomeWindowsusersmayalsobeunabletoopenNetLogoduetographicscardsettingsor

http://windows.microsoft.com/en-US/windows-vista/32-bit-and-64-bit-Windows-frequently-asked-questions

mailto:[email protected]?subject=Sierra NetLogo 6 Bug

mailto:[email protected]?subject=Sierra NetLogo 6 Bug Workaround

https://support.apple.com/en-us/HT202043

drivers.IfyouareunabletoopenNetLogoonWindows,youmightbeabletofixthisbyupdatingorreinstallingyourgraphicsdriverand/ordisablinganygraphicscardutilities.BecauseNetLogomightbeunabletostartforanumberofreasons,weencourageyoutocontactusifthesestepsaren'teffectiveinresolvingtheproblem.

CanIrunNetLogofromthecommandline,withouttheGUI?

Yes.TheeasiestwayistosetupyourmodelrunorrunsasaBehaviorSpaceexperiment.Noadditionalprogrammingisrequired.SeetheBehaviorSpaceGuidefordetails.

AnotheroptionistouseourControllingAPI.SomelightJavaprogrammingisrequired.SeetheControllingAPIGuidefordetailsandsamplecode.

DoesNetLogotakeadvantageofmultipleprocessors?

OnlywhenusingBehaviorSpace.BehaviorSpacedoesparallelruns,oneperprocessor.

Forasinglemodelrun,onlyoneprocessorisused.

Weareseekingfundingtomakeitpossibletosplitasinglemodelrunacrossmultipleprocessorsormultiplecomputers.

CanIdistributeNetLogomodelrunsacrossaclusterorgridofcomputers?

Manyofthesamecommentsinthepreviousanswerapply.Itisnotpossibletosplitasinglemodelrunacrossmultiplecomputers,butyoucanhaveeachmachineinaclusterdoingoneormoreseparate,independentmodelruns,usingeitherBehaviorSpaceorourControllingAPI.Wedon'thaveautomatedsupportforsplittingtherunsacrossclusters,soyou'llneedtoarrangethatyourself.

VarioususersarealreadyusingNetLogoonclusters,withavarietyofhardwareandsoftware.YoucanseekthemoutontheNetLogoUsersGroup.

IsthereanywaytorecoverlostworkifNetLogocrashesorfreezes?

Yes.NetLogoauto-savesfilesasyouareworkingonthem.Thepathtotheauto-savefiledependsonwhetherornottheNetLogomodelhasbeensaved.

ForNetLogomodelswhichhavebeensaved,ahiddenfilewiththename".filename.tmp.nlogo"willbecreatedinthesamedirectoryastheNetLogomodel.

ForunsavedNetLogomodels,autosavefilescanbefoundinyourOS-specificjavatemporarydirectory.Thefilesarenamedaccordingtothefollowingformat:autosave_yyyy-MM-dd.HH_mm_ss.nlogowherethetimeanddatearethetimeanddatethemodelwasopened.Theexactpathwilldependonyouroperatingsystem:

OnMacOS,thetemporarydirectoryis/var/folders/68/<30-character-alphanumeric-sequence>/T/.The30-character-alphanumeric-sequenceisuniquetoeachmachine.OnWindowsthelogscanbefoundinC:\Users\<user>\AppData\Local\Temp,where<user>istheloggedinuser.Onmostnon-MacUnix-likesystemsthetempdirectoryis/tmp.

mailto:[email protected]?subject=NetLogo 6 Launch Problem in Windows

https://github.com/NetLogo/NetLogo/wiki/Controlling-API

Usage

WhenImovethespeedsliderallthewaytotheright,whydoesmymodelseemtostop?

TheonlywayNetLogocanmakeyourmodelrunfasterisbyupdatingtheviewlessfrequently.Asyoumovethespeedslidertotheright,viewupdatesbecomelessandlessfrequent.Sinceviewupdatestaketime,thatmeansmorespeed.

However,fewerupdatesalsomeansthattheupdatescomefartherapart.Whenseveralsecondspassbetweenupdates,itmayseemlikeyourmodelhasstopped.Ithasn't.It'srunningatfullspeed.Watchthetickcounter!(Ifyourmodelusesit.Ifitdoesn't,watchsomethingelse,likeaplot.)

Togetafeelforwhat'sgoingon,trymovingtheslidertotherightgraduallyratherthansuddenly.Ifyoufindtheupdatestooinfrequentattherightmostposition,justdon'tpushthesliderthatfar.

CanIusethemouseto"paint"intheview?

NetLogodoesnothaveabuilt-insetofpaintingtoolsforpaintingintheview.Butwithonlyafewlinesofcode,youcanaddpaintingcapabilitytoyourmodel.Toseehowit'sdone,lookatMouseExample,intheCodeExamplessectionoftheModelsLibrary.Thesametechniquescanbeusedtolettheuserinteractwithyourmodelusingthemouseinotherways,too.

AnotherpossibilityistocreateanimageinanotherprogramandimportitusingtheimportitemsontheFilemenuortheimport-*primitives.

Howbigcanmymodelbe?Howmanyturtles,patches,procedures,buttons,andsooncanmymodelcontain?

WehavetestedNetLogowithmodelsthatusehundredsofmegabytesofRAMandtheyworkfine.Wehaven'ttestedmodelsthatusegigabytesofRAM,though.Theoreticallyitshouldwork,butyoumighthitsomelimitsthatareinherentintheunderlyingJavaVMand/oroperatingsystem(eitherdesigned-inlimits,orbugs).

TheNetLogoenginehasnofixedlimitsonsize.Bydefault,though,NetLogoshipswithaone-gigabyteceilingonhowmuchtotalRAMitcanuse.Ifyourmodelexceedsthatlimit,you'llgetanOutOfMemoryErrordialog.

IfyouareusingBehaviorSpace,notethatdoingrunsinparallelwillmultiplyyourRAMusageaccordingly.

Eachplatformcontains".cfg"filescontainingJVMsettings.Thereisonecfgfileforeachsub-application(NetLogo,NetLogo3D,HubNetClient,etc.)Althoughthefilelocationvariesbyplatform,theprocessforchangingitisthesame.Locatethesectionofthefilethatlookslikethefollowing:

[JVMOptions]# there may be one or more lines, leave them unchanged-Xmx1024m# there may be one or more lines, leave them unchanged

Modifythevalueimmediatelyfollowing

-Xmx

,changingittotheamountofspaceyouneed,savethefile,andrestartNetLogo.Platformspecificnotesfollow:

Windows:Thecfgfileswillbein

C:\Program Files (x86)\NetLogo 6.0.2\app

ifyouarerunning64-bitwindows,and

C:\Program Files\NetLogo 6.0.2\app

otherwise.MacOSX:ThefileforNetLogowillbelocatedat:

/Application/NetLogo 6.0.2/NetLogo.app/Contents/Java/NetLogo.cfg

ForNetLogo3Dandtheotherapplications,youwillfindthefileinthecorrespondinglocationforeachapplicationpackage.Youcanreachthecfgfilebycontrol-clickingtheapplicationintheFinderandchoosing"ShowPackageContents"fromthepopupmenu.

PleasenotethatdependingonyourversionofMacOSX,changingthecfgfile*may*breakapplicationsigning.Ifthishappens,followApple'sdirectionsonthispagetotemporarilyallowappsfrom"Anywhere",runNetLogoonce,thenrestorethesettingto"MacAppStoreandIdentifiedDevelopers".

Other:Thecfgfileswillbelocatedinthe

netlogo-6.0.2/app

folderafteruntarring.

Bydefault,MacbuildsofNetLogobundlea64-bitJVM,whichshouldbeabletomakeuseofasmuchmemoryasthelesserofavailablesystemmemoryandthevaluefollowing

-Xmx

.WindowsandLinuxwillbundlea32-bitor64-bitJVM,dependingonwhichversionyouhavedownloaded.Itisrecommendedthatyouinstall64-bitNetLogoonall64-bitoperatingsystemsforbestperformance.

CanIuseGISdatainNetLogo?

Yes,manyusersareusingGISdatawithNetLogo.ThemostcompletewaytodothatiswiththeGISextension.SeetheGISExtensionGuide.

Asimplerwayistouseimport-pcolors,butthatonlyworksforimportingmapsthatareimages,notmapsinotherformats.

https://support.apple.com/en-us/HT202491

ItisalsopossibletowriteNetLogocodethatreadsGISdatausingourfileI/Oprimitivessuchasfile-open.Forexample,seetheGrandCanyonmodelintheEarthSciencesectionofSampleModels.

Mymodelrunsslowly.HowcanIspeeditup?

Here'ssomewaystomakeitrunfasterwithoutchangingthestructureofthecode:

Usetick-basedviewupdates,notcontinuousupdates.Decreasethefrequencyofviewupdatesbypushingthespeedslidertotheright,orturnupdatesoffusingthecheckbox.IfyourmodelisusingallavailableRAMonyourcomputer,theninstallingmoreRAMshouldhelp.Ifyourharddrivemakesalotofnoisewhileyourmodelisrunning,youprobablyneedmoreRAM.Useturtlesize1,1.5,or2,asthe2DrenderingsforthesesizesarecachedbyNetLogo.(Thisonlyaffectsgraphicsspeedinthe2Dview,notcomputationspeed.)

Inmanycases,though,ifyouwantyourmodeltorunfaster,youmayneedtomakesomechangestothecode.Usuallythemostobviousopportunityforspeedupisthatyou'redoingtoomanycomputationsthatinvolvealltheturtlesorallthepatches.Oftenthiscanbereducedbyreworkingthemodelsothatitdoeslesscomputationpertimestep.ThemembersoftheNetLogoUsersGroupmaybeabletohelpwiththis.

Theprofilerextensionisusefulforidentifyingwhichpartsofyourcodearetakingthemosttime.

Unlessyouarerunningtheexactsamestringsoverandover,usingrunandrunresultaremuchslowerthanrunningcodedirectly;youshouldavoidusingtheseprimitivesonfreshstringsinperformance-criticalcode.

CanIhavemorethanonemodelopenatatime?

OneinstanceofNetLogocanonlyhaveonemodelopenatatime.(Unfortunately,itisunlikelythatthiswillchangeinafutureversion,duetotheengineeringdifficultiesinvolved.)

YoucanhavemultiplemodelsopenbyopeningmultipleinstancesofNetLogo,though.OnWindowsandLinux,simplystarttheapplicationagain.OnaMac,you'llneedtoduplicatetheapplication(notthewholefolder,justtheapplicationitself)intheFinder,thenopenthecopy.(Thecopytakesuponlyaverysmallamountofadditionaldiskspace.)

CanIchangethechoicesinachooseronthefly?

No.

CanIdividethecodeformymodelupintoseveralfiles?

Onanexperimentalbasis,thisisavailableusingthe__includeskeyword.

Programming

HowdoestheNetLogolanguagedifferfromotherLogos?


ThisisansweredindetailattheendoftheProgrammingGuide.

HowcomemymodelfromanearlierNetLogodoesn'tworkright?

SeetheTransitionGuideforhelp.

HowdoItakethenegativeofanumber?

Anyoftheseways:

(- x)-1 * x0 - x

Withthefirstway,theparenthesesarerequired.

Myturtlemovedforward1,butit'sstillonthesamepatch.Why?

Ifyouhavedisabledwrappingattheworldedgesinyourmodel,thentheturtlemightbeataworldedgeandunabletomoveanyfurther.Youcantestforthisusingcan-move?.

Assumingtheturtleisn'thittingaworldedge,movingforward1isonlyguaranteedtotakeaturtletoanewpatchiftheturtle'sheadingisamultipleof90(thatis,exactlynorth,south,east,orwest).

It'sbecausetheturtlemightnotbestandinginthecenterofapatch.Itmightbenearthecornerofapatch.Forexample,supposeyourturtleisclosetothesouthwestcornerofapatchandisfacingnortheast.Thelengthofthepatchdiagonalis1.414...(thesquarerootoftwo),sofd 1willleavetheturtlenearthenortheastcornerofthesamepatch.

Ifyoudon'twanttohavetothinkabouttheseissues,onepossibilityistowriteyourmodelinsuchawaythatyourturtlesalwayscometorestonpatchcenters.Seenextquestion.

HowdoIkeepmyturtlesonpatchcenters?

Aturtleisonapatchcenterwhenitsxcorandycorareintegers.

Youcanmoveaturtletothecenterofitscurrentpatchwitheitherofthesetwoequivalentcommands:

move-to patch-heresetxy pxcor pycor

Butyou'llneverneedtodothatifyouneverallowturtlesoffofpatchcentersinthefirstplace.

Thesproutcommandcreatesturtlesonpatchcenters.Forexample:

ask n-of 50 patches [ sprout 1 [ face one-of neighbors4 ] ]

Anotherwayforaturtletostartonapatchcenteriswithacommandsuchasthislineofturtlecode,whichmovesittothecenterofarandompatch:

move-to one-of patches

Onceaturtleisonapatchcenter,aslongasitsheadingalwaysstaysanexactmultipleof90(thatistosay,duenorth,east,south,orwest),andasitlongasitmovesforwardorbackbyintegeramounts,itwillalwayslandonpatchcenters.

SeeRandomGridWalkExample,intheCodeExamplessectionoftheModelsLibrary,toseethesecodesnippetsinuse.

patch-ahead 1isreportingthesamepatchmyturtleisalreadystandingon.Why?

Seetheanswertwoanswersup.It'sthesameissue.

Thismightnotbethemeaningof"ahead"youwereexpecting.Withpatch-ahead,youmustspecifythedistanceaheadthatyouwanttolook.Ifyouwanttoknowthenextpatchaturtlewouldcrossintoifitmovedforwardcontinuously,itispossibletofindthatout.SeeNextPatchExample,intheCodeExamplessectionoftheModelsLibrary.

HowdoIgivemyturtles"vision"?

Youcanusein-radiustoletaturtleseeacircularareaaroundit.

Severalprimitiveslettheturtle"look"atspecificpoints.Thepatch-aheadprimitiveisusefulforlettingaturtleseewhatisdirectlyinfrontofit.Ifyouwanttheturtletolookinanotherdirectionbesidesstraightahead,trypatch-left-and-aheadandpatch-right-and-ahead.

Ifyouwanttheturtletohaveafull"cone"ofvision,usethein-coneprimitive.

Youcanalsofindoutthenextpatchaturtlewouldcrossintoifitmovedforwardcontinuously.SeeNextPatchExample,intheCodeExamplessectionoftheModelsLibrary.

Canagentssensewhat'sinthedrawinglayer?

No.Ifyouwanttomakemarksthatagentscansense,usepatchcolors.

I'mgettingnumberslike0.10000000004and0.799999999999insteadof0.1and0.8.Why?

Seethe"Math"sectionoftheProgrammingGuideforadiscussionofthisissue.

Thedocumentationsaysthatrandom-float 1mightreturn0butwillneverreturn1.WhatifIwant1tobeincluded?

Itreallydoesn'tmatter.Evenif1wereapossibleresult,itwouldonlycomeupapproximately1in2^64tries,whichmeansyou'dbewaitinghundredsofyearsbeforeitevercameupexactly1.

Nonetheless,ifyouareconvincedthatitreallymustbepossibletoget1,youcanuseprecisiontoroundyouranswertoacertainnumberofdecimalplaces.Forexample:

print precision (random-float 1) 100.2745173723

(Ifyouusethismethod,notethat0and1areonlyhalfaslikelytocomeupasotheranswers.Toseewhythisisso,considerthecasewhereyouonlykeeponedigitafterthedecimalpoint.Resultsbetween0and0.5getroundedto0,butresultsbetween0.5and1.5getroundedto1;thelatterrangeistwiceaslarge.Ifyouwant0,0.1,0.2,...,0.9,and1toallbeequallylikely,analternativeistowriterandom 11 / 10 ;thisgivesall11answerswithequalprobability.)

HowcanIkeeptwoturtlesfromoccupyingthesamepatch?

SeeOneTurtlePerPatchExample,intheCodeExamplessectionoftheModelsLibrary.

HowcanIfindoutifaturtleisdead?

Whenaturtledies,itturnsintonobody.nobodyisaspecialvalueusedinNetLogousedtoindicatetheabsenceofaturtleorpatch.Soforexample:

if turtle 0 != nobody [ ... ]

Youcouldalsouseis-turtle?:

if is-turtle? turtle 0 [ ... ]

DoesNetLogohavearrays?

Nearlyallmodelsshouldjustuselistsforthis.

Theusualmotivationforusingarraysinotherprogramminglanguagesisthattheyprovidefastrandomaccess(item)andmutation(replace-item).ButNetLogo'slists,eventhoughtheyareimmutable,nowprovidenearconstanttimeperformanceontheseoperations.

ListsinearlierversionsofNetLogo(4.1and4.0)weresimplesingly-linkedlistsandthereforetheseoperationstooklineartime.ThedatastructureunderlyingNetLogo'slistsnowistheimmutableVectorclassfromtheScalacollectionslibrary.Ituses32-widehasharraymappedtries,asimplementedbyTiarkRompf,basedinpartonworkbyPhilBagwellandRichHickey.

Ifyouarecertainyouwanttouseraw,mutableJVMarraysinyourmodel,theyareprovidedbythearrayextension.SeetheArrays&TablessectionoftheUserManual.

DoesNetLogohavehashtablesorassociativearrays?

Yes,usingthetableextension.SeetheArrays&TablessectionoftheUserManual.

HowcanIusedifferentpatch"neighborhoods"(circular,VonNeumann,Moore,etc.)?

Thein-radiusprimitivesletsyouaccesscircularneighborhoodsofanyradius.

http://en.wikipedia.org/wiki/Hash_array_mapped_trie

TheneighborsprimitivegivesyouaMooreneighborhoodofradius1,andtheneighbors4primitivegivesyouaVonNeumannneighborhoodofradius1.

ForMooreorVonNeumannneighborhoodsofalargerradius,seeMoore&VonNeumannExampleintheCodeExamplessectionoftheModelsLibrary.

HowcanIconvertanagentsettoalistofagents,orviceversa?

Ifyouwantthelistinaparticularorder,usethesortorsort-byprimitives.TheListssectionoftheProgrammingGuideexplainshowtodothis.SeealsoAskOrderingExample,intheCodeExamplessectionoftheModelsLibrary.

Ifyouwantthelistinarandomorder,here'show:

[self] of <agentset>

Becausealloperationsonagentsetsareinrandomorder,theresultinglistisinrandomorder.

Toconvertalistofagentstoanagentset,usetheturtle-set,patch-set,orlink-setprimitives.

HowdoIstopforeach?

Tostopaforeachfromexecutingyouneedtodefineaseparateprocedurethatcontainsonlytheforeach,forexample:

to test foreach [1 2 3] [ i -> if i = 2 [ stop ] print i ]end

Thiscodewillonlyprintthenumber1.Thestopreturnsfromthecurrentproceduresonothingaftertheforeachwillbeexecutedeither.(Iftheprocedureisareporterprocedure,usereportinsteadofstop.)

I'mtryingtomakealist.WhydoIkeepgettingtheerror"Expectedaconstant"?

Ifalistcontainsonlyconstants,youcanwriteitdownjustbyputtingsquarebracketsaroundit,like[1 2 3] .

Ifyouwantyourlisttocontainitemsthatmayvaryatruntime,thelistcannotbewrittendowndirectly.Instead,youbuilditusingthelistprimitive.

BehaviorSpace

WhyaretherowsinmyBehaviorSpacetableresultsoutoforder?

Thisisnormalwhendoingmultiplerunsinparallel.Foradiscussionoftheissue,seethe

sectiononparallelrunsintheBehaviorSpaceGuidesectionoftheUserManual.

HowdoImeasurerunseverynticks?

Userepeatinyourexperiment'sgocommands,e.g.:

repeat 10 [ go ]

tomeasuretherunafterevery10ticks.Essentiallyyouaremakingoneexperimentstepequal10ticks.

I'mvaryingaglobalvariableIdeclaredintheCodetab,butitdoesn'twork.Why?

It'sprobablybecauseyoursetupcommandsorsetupprocedureareusingclear-all,causingthevaluessetbyBehaviorSpacetobecleared.

Onepossibleworkaroundistochangeyourexperiment'ssetupcommandstopreservethevalueofthevariable,e.g.:

let old-var1 var1setupset var1 old-var1

Thisworksbecauseevenclear-alldoesn'tclearthevaluesoflocalvariablesmadewithlet

Anotherpossibleworkaroundistochangeyourmodel'ssetupproceduretousemorespecificclearingcommandstoclearonlywhatyouwantcleared.

NetLogo3D

DoesNetLogoworkwithmystereoscopicdevice?

NetLogosupportsfullscreenexclusivemode.Ifthatisallyourdeviceneedsthen,possiblyyes.However,itcanbetrickytogetitworking.Wedon'thaveanysuchdevicessoitisdifficultforustomaketheprocesseasier.Ifyourdeviceneedssomethingelse,forexample,quadbuffersenabled,theanswerisprobablyno.

Extensions

I'mwritinganextension.Whydoesthecompilersayitcan'tfindorg.nlogo.api?

YouneedtoaddNetLogo.jartoyourclasspathwhencompiling.NetLogo.jarisincludedwithNetLogo.

NetLogoDictionaryAlphabetical:ABCDEFGHIJLMNOPRSTUVWXY->

Categories:Turtle-Patch-Links-Agentset-Color-AnonymousProcedures-Control/Logic-WorldPerspective-Input/Output-File-List-String-Math-Plotting-System-HubNet

Special:Variables-Keywords-Constants

Categories

Thisisanapproximategrouping.Rememberthataturtle-relatedprimitivemightstillbeusedbypatchesortheobserver,andviceversa.Toseewhichagents(turtles,patches,links,observer)canactuallyrunaprimitive,consultitsdictionaryentry.

Turtle-related

back(bk)<breeds>-at<breeds>-here<breeds>-oncan-move?clear-turtles(ct)create-<breeds>create-ordered-<breeds>create-ordered-turtles(cro)create-turtles(crt)diedistancedistancexydownhilldownhill4dxdyfacefacexyforward(fd)hatchhatch-<breeds>hide-turtle(ht)homeinspectis-<breed>?is-turtle?jumplayout-circleleft(lt)move-tomyselfnobodyno-turtlesofotherpatch-aheadpatch-atpatch-at-heading-and-distancepatch-herepatch-left-and-aheadpatch-right-and-aheadpen-down(pd)pen-erase(pe)pen-up(pu)random-xcorrandom-ycorright(rt)selfset-default-shape__set-line-thicknesssetxyshapesshow-turtle(st)sproutsprout-<breeds>stampstamp-erasestop-inspectingsubjectsubtract-headingstietowardstowardsxyturtleturtle-setturtlesturtles-atturtles-hereturtles-onturtles-ownuntieuphilluphill4

Patch-related

clear-patches(cp)diffusediffuse4distancedistancexyimport-pcolorsimport-pcolors-rgbinspectis-patch?myselfneighborsneighbors4nobodyno-patchesofotherpatchpatch-atpatch-aheadpatch-at-heading-and-distancepatch-herepatch-left-and-aheadpatch-right-and-aheadpatch-setpatchespatches-ownrandom-pxcorrandom-pycorselfsproutsprout-<breeds>stop-inspectingsubjectturtles-here

Link-related

both-endsclear-linkscreate-<breed>-fromcreate-<breeds>-fromcreate-<breed>-tocreate-<breeds>-tocreate-<breed>-withcreate-<breeds>-withcreate-link-fromcreate-links-fromcreate-link-tocreate-links-tocreate-link-withcreate-links-withdiehide-linkin-<breed>-neighbor?in-<breed>-neighborsin-<breed>-fromin-link-neighbor?in-link-neighborsin-link-fromis-directed-link?is-link?is-link-set?is-<link-breed>?is-undirected-link?layout-radiallayout-springlayout-tutte<breed>-neighbor?<breed>-neighbors<breed>-withlink-headinglink-lengthlink-neighbor?linklinkslinks-own<link-breeds>-ownlink-neighborslink-withmy-<breeds>my-in-<breeds>my-in-linksmy-linksmy-out-<breeds>my-out-linksno-linksother-endout-<breed>-neighbor?out-<breed>-neighborsout-<breed>-toout-link-neighbor?out-link-neighborsout-link-toshow-linktieuntie

Agentset

all?any?askask-concurrentat-points<breeds>-at<breeds>-here<breeds>-oncountin-conein-radiusis-agent?is-agentset?is-patch-set?is-turtle-set?link-setmax-n-ofmax-one-ofmember?min-n-ofmin-one-ofn-ofneighborsneighbors4no-linksno-patchesno-turtlesofone-ofotherpatch-setpatchessortsort-bysort-onturtle-setturtlesturtles-atturtles-hereturtles-onwithwith-maxwith-min

Color

approximate-hsbapproximate-rgbbase-colorscolorextract-hsbextract-rgbhsbimport-pcolorsimport-pcolors-rgbpcolorrgbscale-colorshade-of?wrap-color

Controlflowandlogic

andaskask-concurrentcarefullyenderrorerror-messageeveryififelseifelse-valueletloopnotorrepeatreportrunrunresult;(semicolon)setstopstartuptoto-reportwaitwhilewith-local-randomnesswithout-interruptionxor

AnonymousProcedures

->(anonymousprocedure)filterforeachis-anonymous-command?is-anonymous-reporter?mapn-valuesreducerunrunresultsort-by

World

clear-all(ca)clear-drawing(cd)clear-globalsclear-patches(cp)clear-ticksclear-turtles(ct)displayimport-drawingimport-pcolorsimport-pcolors-rgbno-displaymax-pxcormax-pycormin-pxcormin-pycorpatch-sizereset-ticksresize-worldset-patch-sizestop-inspecting-dead-agentsticktick-advanceticksworld-widthworld-height

Perspective

followfollow-mereset-perspective(rp)rideride-mesubjectwatchwatch-me

HubNet

hubnet-broadcasthubnet-broadcast-clear-outputhubnet-broadcast-messagehubnet-clear-overridehubnet-clear-overrideshubnet-clients-listhubnet-enter-message?hubnet-exit-message?hubnet-kick-all-clientshubnet-kick-clienthubnet-fetch-messagehubnet-messagehubnet-message-sourcehubnet-message-taghubnet-message-waiting?hubnet-resethubnet-reset-perspectivehubnet-sendhubnet-send-clear-outputhubnet-send-followhubnet-send-messagehubnet-send-overridehubnet-send-watch

Input/output

beepclear-outputdate-and-timeexport-viewexport-interfaceexport-outputexport-plotexport-all-plotsexport-worldimport-drawingimport-

pcolorsimport-pcolors-rgbimport-worldmouse-down?mouse-inside?mouse-xcormouse-ycoroutput-printoutput-showoutput-typeoutput-writeprintread-from-stringreset-timerset-current-directoryshowtimertypeuser-directoryuser-fileuser-new-fileuser-inputuser-messageuser-one-ofuser-yes-or-no?write

File

file-at-end?file-closefile-close-allfile-deletefile-exists?file-flushfile-openfile-printfile-readfile-read-charactersfile-read-linefile-showfile-typefile-writeuser-directoryuser-fileuser-new-file

List

but-firstbut-lastempty?filterfirstforeachfputhistograminsert-itemis-list?itemlastlengthlistlputmapmaxmember?minmodesn-ofn-valuesofpositionone-ofrangereduceremoveremove-duplicatesremove-itemreplace-itemreversesentenceshufflesortsort-bysort-onsublist

String

Operators(<,>,=,!=,<=,>=)but-firstbut-lastempty?firstinsert-itemis-string?itemlastlengthmember?positionremoveremove-itemread-from-stringreplace-itemreversesubstringword

Mathematical

ArithmeticOperators(+,*,-,/,^,<,>,=,!=,<=,>=)absacosasinatanceilingcoseexpfloorintis-number?lnlogmaxmeanmedianminmodmodesnew-seedpiprecisionrandomrandom-exponentialrandom-floatrandom-gammarandom-normalrandom-poissonrandom-seedremainderroundsinsqrtstandard-deviationsubtract-headingssumtanvariance

Plotting

autoplot?auto-plot-offauto-plot-onclear-all-plotsclear-plotcreate-temporary-plot-penexport-plotexport-all-plotshistogramplotplot-nameplot-pen-exists?plot-pen-downplot-pen-resetplot-pen-upplot-x-maxplot-x-minplot-y-maxplot-y-minplotxyset-current-plotset-current-plot-penset-histogram-num-barsset-plot-background-colorset-plot-pen-colorset-plot-pen-intervalset-plot-pen-modeset-plot-x-rangeset-plot-y-rangesetup-plotsupdate-plots

BehaviorSpace

behaviorspace-experiment-namebehaviorspace-run-number

System

netlogo-versionnetlogo-web?

Built-InVariables

Turtles

breedcolorheadinghidden?labellabel-colorpen-modepen-sizeshapesizewhoxcorycor

Patches

pcolorplabelplabel-colorpxcorpycor

Links

breedcolorend1end2hidden?labellabel-colorshapethicknesstie-mode

Other

->

Keywords

breeddirected-link-breedendextensionsglobals__includeslinks-ownpatches-owntoto-reportturtles-ownundirected-link-breed

Constants

MathematicalConstants

e=2.718281828459045pi=3.141592653589793

BooleanConstants

falsetrue

ColorConstants

Since1.0

Since1.3

Since4.0

Since1.0

Since2.0

black=0gray=5white=9.9red=15orange=25brown=35yellow=45green=55lime=65turquoise=75cyan=85sky=95blue=105violet=115magenta=125pink=135

SeetheColorssectionoftheProgrammingGuideformoredetails.

A

abs

absnumber

Reportstheabsolutevalueofnumber.

show abs -7=> 7show abs 5=> 5

acos

acosnumber

Reportsthearccosine(inversecosine)ofthegivennumber.Theinputmustbeintherange-1to1.Theresultisindegrees,andliesintherange0to180.

all?

all?agentset[reporter]

Reportstrueifalloftheagentsintheagentsetreporttrueforthegivenreporter.Otherwisereportsfalseassoonasacounterexampleisfound.

Iftheagentsetisempty,reportstrue.

Thereportermustreportabooleanvalueforeveryagent(eithertrueorfalse),otherwiseanerroroccurs.

if all? turtles [color = red] [ show "every turtle is red!" ]

Seealsoany?.

and

condition1andcondition2

Reportstrueifbothcondition1andcondition2aretrue.

Notethatifcondition1isfalse,thencondition2willnotberun(sinceitcan'taffecttheresult).

if (pxcor > 0) and (pycor > 0) [ set pcolor blue ] ;; the upper-right quadrant of ;; patches turn blue

any?

any?agentset

Reportstrueifthegivenagentsetisnon-empty,falseotherwise.

Equivalentto"countagentset>0",butmoreefficient(andarguablymorereadable).

if any? turtles with [color = red] [ show "at least one turtle is red!" ]

Note:nobodyisnotanagentset.Youonlygetnobodybackinsituationswhereyouwereexpectingasingleagent,notawholeagentset.If

Since4.0

Since4.0

Since1.0Since1.0Since1.0Since1.0Since1.0Since1.0Since1.0Since1.0Since1.0Since1.0Since1.0

any?getsnobodyasinput,anerrorresults.

Seealsoall?,nobody.

approximate-hsb

approximate-hsbhuesaturationbrightness

Reportsanumberintherange0to140,notincluding140itself,thatrepresentsthegivencolor,specifiedintheHSBspectrum,inNetLogo'scolorspace.

Thefirstvalue(hue)shouldbeintherangeof0to360,thesecondandthird(saturationandbrightness)intherangebetween0and100.

Thecolorreportedmaybeonlyanapproximation,sincetheNetLogocolorspacedoesnotincludeallpossiblecolors.

show approximate-hsb 0 0 0=> 0 ;; (black)show approximate-hsb 180 57.143 76.863=> 85 ;; (cyan)

Seealsoextract-hsb,approximate-rgb,extract-rgb.

approximate-rgb

approximate-rgbredgreenblue

Reportsanumberintherange0to140,notincluding140itself,thatrepresentsthegivencolor,specifiedintheRGBspectrum,inNetLogo'scolorspace.

Allthreeinputsshouldbeintherange0to255.

Thecolorreportedmaybeonlyanapproximation,sincetheNetLogocolorspacedoesnotincludeallpossiblecolors.(Seeapproximate-hsbforadescriptionofwhatpartsoftheHSBcolorspaceNetLogocolorscover;thisisdifficulttocharacterizeinRGBterms.)

show approximate-rgb 0 0 0=> 0 ;; blackshow approximate-rgb 0 255 255=> 85.2 ;; cyan

Seealsoextract-rgb,approximate-hsb,andextract-hsb.

ArithmeticOperators+*-/^<>=!=<=>=

Alloftheseoperatorstaketwoinputs,andallactas"infixoperators"(goingbetweenthetwoinputs,asinstandardmathematicaluse).NetLogocorrectlysupportsorderofoperationsforinfixoperators.

Theoperatorsworkasfollows:+isaddition,*ismultiplication,-issubtraction,/isdivision,^isexponentiation,<islessthan,>isgreaterthan,=isequalto,!=isnotequalto,<=islessthanorequal,>=isgreaterthanorequal.

Notethatthesubtractionoperator(-)alwaystakestwoinputsunlessyouputparenthesesaroundit,inwhichcaseitcantakeoneinput.Forexample,totakethenegativeofx,write(-x),withtheparentheses.

Allofthecomparisonoperatorsalsoworkonstrings.

Allofthecomparisonoperatorsworkonagents.Turtlesarecomparedbywhonumber.Patchesarecomparedtoptobottomlefttoright,sopatch010islessthanpatch09andpatch90islessthanpatch100.Linksareorderedbyendpointsandincaseofatiebybreed.Solink09isbeforelink110astheend1issmaller,andlink08islessthanlink09.IftherearemultiplebreedsoflinksunbreededlinkswillcomebeforebreededlinksofthesameendpointsandbreededlinkswillbesortedintheordertheyaredeclaredintheCodetab.

Agentsetscanbetestedforequalityorinequality.Twoagentsetsareequaliftheyarethesametype(turtleorpatch)andcontainthesameagents.

IfyouarenotsurehowNetLogowillinterpretyourcode,youshouldaddparentheses.

show 5 * 6 + 6 / 3=> 32show 5 * (6 + 6) / 3=> 20

Manyextensionobjectsmaybetestedforequalityandinequalityusing=and!=.Forinstance,thearray,matrix,andtableobjectsreturnedbytheirrespectiveextensionsmaybecomparedforequality/inequality.Extensionobjectsmaynotbetestedusing<,>,<=,or>=.

Since1.3

Since1.0

Since4.0

Since1.0

Since1.0

asin

asinnumber

Reportsthearcsine(inversesine)ofthegivennumber.Theinputmustbeintherange-1to1.Theresultisindegrees,andliesintherange-90to90.

ask

askagentset[commands]askagent[commands]

Thespecifiedagentoragentsetrunsthegivencommands.

ask turtles [ fd 1 ] ;; all turtles move forward one stepask patches [ set pcolor red ] ;; all patches turn redask turtle 4 [ rt 90 ] ;; only the turtle with id 4 turns right

Note:onlytheobservercanaskallturtlesorallpatches.Thispreventsyoufrominadvertentlyhavingallturtlesaskallturtlesorallpatchesaskallpatches,whichisacommonmistaketomakeifyou'renotcarefulaboutwhichagentswillrunthecodeyouarewriting.

Note:Onlytheagentsthatareintheagentsetatthetimetheaskbeginsrunthecommands.

ask-concurrent

ask-concurrentagentset[commands]

Thisprimitiveexistsonlyforbackwardscompatibility.Wedon'trecommendusingitnewmodels.

Theagentsinthegivenagentsetrunthegivencommands,usingaturn-takingmechanismtoproducesimulatedconcurrency.SeetheAsk-ConcurrentsectionoftheProgrammingGuidefordetailsonhowthisworks.

Note:Onlytheagentsthatareintheagentsetatthetimetheaskbeginsrunthecommands.

Seealsowithout-interruption.

at-points

agentsetat-points[[x1y1][x2y2]...]

Reportsasubsetofthegivenagentsetthatincludesonlytheagentsonthepatchesatthegivencoordinates(relativetothisagent).Thecoordinatesarespecifiedasalistoftwo-itemlists,wherethetwoitemsarethexandyoffsets.

Ifthecalleristheobserver,thenthepointsaremeasuredrelativetotheorigin,inotherwords,thepointsaretakenasabsolutepatchcoordinates.

Ifthecallerisaturtle,thepointsaremeasuredrelativetotheturtle'sexactlocation,andnotfromthecenterofthepatchundertheturtle.

ask turtles at-points [[2 4] [1 2] [10 15]] [ fd 1 ] ;; only the turtles on the patches at the ;; coordinates (2,4), (1,2) and (10,15), ;; relative to the caller, move

atan

atanxy

Convertsxandyoffsetstoaturtleheadingindegrees(from0to360).

NotethatthisversionofatanisdesignedtoconformtothegeometryoftheNetLogoworld,whereaheadingof0isstraightup,90istotheright,andsoonclockwisearoundthecircle.(Normallyingeometryanangleof0isright,90isup,andsoon,counterclockwisearoundthecircle,andatanwouldbedefinedaccordingly.)

Whenyis0:ifxispositive,itreports90;ifxisnegative,itreports270;ifxiszero,yougetanerror.

show atan 1 -1=> 135show atan -1 1=> 315crt 1 [ set heading 30 fd 1 print atan xcor ycor ]=> 30

Inthefinalexample,notethattheresultofatanequalstheturtle'sheading.

Ifyoueverneedtoconvertaturtleheading(obtainedwithatanorotherwise)toanormalmathematicalangle,thefollowingshouldbehelpful:

to-report heading-to-angle [ h ] report (90 - h) mod 360end

Since1.0

Since1.0Since1.0

Since1.0Since1.0

Since4.0

Since2.1

Since5.2

Since4.1.1

autoplot?

autoplot?

Reportstrueifauto-plottingisonforthecurrentplot,falseotherwise.

auto-plot-offauto-plot-on

auto-plot-offauto-plot-on

ThispairofcommandsisusedtocontroltheNetLogofeatureofauto-plottinginthecurrentplot.Auto-plottingwillautomaticallyupdatethexandyaxesoftheplotwheneverthecurrentpenexceedstheseboundaries.Itisusefulwhenwantingtoshowallplottedvaluesinthecurrentplot,regardlessofthecurrentplotranges.

B

backbk

backnumber

Theturtlemovesbackwardbynumbersteps.(Ifnumberisnegative,theturtlemovesforward.)

Turtlesusingthisprimitivecanmoveamaximumofoneunitpertimeincrement.Sobk 0.5andbk 1bothtakeoneunitoftime,butbk 3takesthree.

Iftheturtlecannotmovebackwardnumberstepsbecauseitisnotpermittedbythecurrenttopologytheturtlewillcompleteasmanystepsof1asitcanandstop.

Seealsoforward,jump,can-move?.

base-colors

base-colors

Reportsalistofthe14basicNetLogohues.

print base-colors=> [5 15 25 35 45 55 65 75 85 95 105 115 125 135]ask turtles [ set color one-of base-colors ];; each turtle turns a random base colorask turtles [ set color one-of remove gray base-colors ];; each turtle turns a random base color except for gray

beep

beep

Emitsabeep.Notethatthebeepsoundsimmediately,soseveralbeepcommandsinclosesuccessionmayproduceonlyoneaudiblesound.

Example:

beep ;; emits one beeprepeat 3 [ beep ] ;; emits 3 beeps at once, ;; so you only hear one soundrepeat 3 [ beep wait 0.1 ] ;; produces 3 beeps in succession, ;; separated by 1/10th of a second

Whenrunningheadless,thiscommandhasnoeffect.

behaviorspace-experiment-name

behaviorspace-experiment-name

Reportsthecurrentexperimentnameinthecurrentexperiment.

IfnoBehaviorSpaceexperimentisrunning,reports"".

behaviorspace-run-number

behaviorspace-run-number

ReportsthecurrentrunnumberinthecurrentBehaviorSpaceexperiment,startingat1.

IfnoBehaviorSpaceexperimentisrunning,reports0.

Since4.0

Since1.0Since1.0Since1.0Since1.0Since1.0Since1.0

both-ends

both-ends

Reportstheagentsetofthe2nodesconnectedbythislink.

crt 2ask turtle 0 [ create-link-with turtle 1 ]ask link 0 1 [ ask both-ends [ set color red ] ;; turtles 0 and 1 both turn red]

breed

breed

Thisisabuilt-inturtleandlinkvariable.Itholdstheagentsetofallturtlesorlinksofthesamebreedasthisturtleorlink.(Forturtlesorlinksthatdonothaveanyparticularbreed,thisistheturtlesagentsetofallturtlesorthelinksagentsetofalllinksrespectively.)

Youcansetthisvariabletochangeaturtleorlink'sbreed.(Whenaturtlechangesbreeds,itsshapeisresettothedefaultshapeforthatbreed.Seeset-default-shape.)

Seealsobreed,directed-link-breed,undirected-link-breed

Example:

breed [cats cat]breed [dogs dog];; turtle code:if breed = cats [ show "meow!" ]set breed dogsshow "woof!"

directed-link-breed [ roads road ];; link codeif breed = roads [ set color gray ]

breed

breed[<breeds><breed>]

Thiskeyword,liketheglobals,turtles-own,andpatches-ownkeywords,canonlybeusedatthebeginningoftheCodetab,beforeanyproceduredefinitions.Itdefinesabreed.Thefirstinputdefinesthenameoftheagentsetassociatedwiththebreed.Thesecondinputdefinesthenameofasinglememberofthebreed.

Anyturtleofthegivenbreed:

ispartoftheagentsetnamedbythebreednamehasitsbreedbuilt-invariablesettothatagentset

Mostoften,theagentsetisusedinconjunctionwithasktogivecommandstoonlytheturtlesofaparticularbreed.

breed [mice mouse]breed [frogs frog]to setup clear-all create-mice 50 ask mice [ set color white ] create-frogs 50 ask frogs [ set color green ] show [breed] of one-of mice ;; prints mice show [breed] of one-of frogs ;; prints frogsend

show mouse 1;; prints (mouse 1)show frog 51;; prints (frog 51)show turtle 51;; prints (frog 51)

Seealsoglobals,patches-own,turtles-own,<breeds>-own,create-<breeds>,<breeds>-at,<breeds>-here.

but-firstbutfirstbfbut-lastbutlastbl

but-firstlistbut-firststringbut-lastlistbut-laststring

Since3.1

Since2.1

Since1.0

Since1.0Since1.0

Since1.0

Since3.0Since3.0

Since5.2

Whenusedonalist,but-firstreportsallofthelistitemsoflistexceptthefirst,andbut-lastreportsallofthelistitemsoflistexceptthelast.

Onstrings,but-firstandbut-lastreportashorterstringomittingthefirstorlastcharacteroftheoriginalstring.

;; mylist is [2 4 6 5 8 12]set mylist but-first mylist;; mylist is now [4 6 5 8 12]set mylist but-last mylist;; mylist is now [4 6 5 8]show but-first "string";; prints "tring"show but-last "string";; prints "strin"

C

can-move?

can-move?distance

Reportstrueifthisturtlecanmovedistanceinthedirectionitisfacingwithoutviolatingthetopology;reportsfalseotherwise.

Itisequivalentto:

patch-ahead distance != nobody

carefully

carefully[commands1][commands2]

Runscommands1.Ifaruntimeerroroccursinsidecommands1,NetLogowon'tstopandalerttheuserthatanerroroccurred.Itwillsuppresstheerrorandruncommands2instead.

Theerror-messagereportercanbeusedincommands2tofindoutwhaterrorwassuppressedincommands1.Seeerror-message.

carefully [ print one-of [1 2 3] ] [ print error-message ]=> 3observer> carefully [ print one-of [] ] [ print error-message ]=> ONE-OF got an empty list as input.

ceiling

ceilingnumber

Reportsthesmallestintegergreaterthanorequaltonumber.

show ceiling 4.5=> 5show ceiling -4.5=> -4

Seealsofloor,round,precision.

clear-allca

clear-all

Combinestheeffectsofclear-globals,clear-ticks,clear-turtles,clear-patches,clear-drawing,clear-all-plots,andclear-output.

clear-all-plots

clear-all-plots

Clearseveryplotinthemodel.Seeclear-plotformoreinformation.

clear-drawingcd

clear-drawing

Clearsalllinesandstampsdrawnbyturtles.

clear-globals

Since4.0

Since1.0

Since1.0Since1.0

Since5.0

Since1.0Since1.0

clear-globals

Setsallglobalvariablesto0.

clear-links

clear-links

Killsalllinks.

Seealsodie.

clear-output

clear-output

Clearsalltextfromthemodel'soutputarea,ifithasone.Otherwisedoesnothing.

clear-patchescp

clear-patches

Clearsthepatchesbyresettingallpatchvariablestotheirdefaultinitialvalues,includingsettingtheircolortoblack.

clear-plot

clear-plot

Inthecurrentplotonly,resetsallplotpens,deletesalltemporaryplotpens,resetstheplottoitsdefaultvalues(forxrange,yrange,etc.),andresetsallpermanentplotpenstotheirdefaultvalues.ThedefaultvaluesfortheplotandforthepermanentplotpensaresetintheplotEditdialog,whichisdisplayedwhenyouedittheplot.Iftherearenoplotpensafterdeletingalltemporarypens,thatistosayiftherearenopermanentplotpens,adefaultplotpenwillbecreatedwiththefollowinginitialsettings:

Pen:downColor:blackMode:0(linemode)Name:"default"Interval:1

Seealsoclear-all-plots.

clear-ticks

clear-ticks

Clearsthetickcounter.

Doesnotsetthecountertozero.Afterthiscommandruns,thetickcounterhasnovalue.Attemptingtoaccessorupdateitisanerroruntilreset-ticksiscalled.

Seealsoreset-ticks.

clear-turtlesct

clear-turtles

Killsallturtles.

Alsoresetsthewhonumbering,sothenextturtlecreatedwillbeturtle0.

Seealsodie.

color

color

Thisisabuilt-inturtleorlinkvariable.Itholdsthecoloroftheturtleorlink.Youcansetthisvariabletomaketheturtleorlinkchangecolor.ColorcanberepresentedeitherasaNetLogocolor(asinglenumber),oranRGBcolor(alistof3numbers).SeedetailsintheColorssectionoftheProgrammingGuide.

Since1.0

Since1.0

Since4.0Since4.0


Seealsopcolor.

cos

cosnumber

Reportsthecosineofthegivenangle.Assumestheangleisgivenindegrees.

show cos 180=> -1

count

countagentset

Reportsthenumberofagentsinthegivenagentset.

show count turtles;; prints the total number of turtlesshow count patches with [pcolor = red];; prints the total number of red patches

create-ordered-turtlescro

create-ordered-turtlesnumbercreate-ordered-turtlesnumber[commands]create-ordered<breeds>numbercreate-ordered<breeds>number[commands]

Createsnumbernewturtles.Newturtlesstartatposition(0,0),arecreatedwiththe14primarycolors,andhaveheadingsfrom0to360,evenlyspaced.

Ifthecreate-ordered-<breeds>formisused,thenewturtlesarecreatedasmembersofthegivenbreed.

Ifcommandsaresupplied,thenewturtlesimmediatelyrunthem.Thisisusefulforgivingthenewturtlesadifferentcolor,heading,orwhatever.(Thenewturtlesarecreatedallatoncethenrunoneatatime,inrandomorder.)

cro 100 [ fd 10 ] ;; makes an evenly spaced circle

create-<breed>-tocreate-<breeds>-tocreate-<breed>-fromcreate-<breeds>-fromcreate-<breed>-withcreate-<breeds>-withcreate-link-tocreate-links-tocreate-link-fromcreate-links-fromcreate-link-withcreate-links-with

create-<breed>-toturtlecreate-<breed>-toturtle[commands]create-<breed>-fromturtlecreate-<breed>-fromturtle[commands]create-<breed>-withturtlecreate-<breed>-withturtle[commands]create-<breeds>-toturtlesetcreate-<breeds>-toturtleset[commands]create-<breeds>-fromturtlesetcreate-<breeds>-fromturtleset[commands]create-<breeds>-withturtlesetcreate-<breeds>-withturtleset[commands]create-link-toturtlecreate-link-toturtle[commands]create-link-fromturtlecreate-link-fromturtle[commands]create-link-withturtlecreate-link-withturtle[commands]create-links-toturtlesetcreate-links-toturtleset[commands]create-links-fromturtlesetcreate-links-fromturtleset[commands]create-links-withturtlesetcreate-links-withturtleset[commands]

Since1.0Since1.0

Since1.1

Usedforcreatingbreededandunbreededlinksbetweenturtles.

create-link-withcreatesanundirectedlinkbetweenthecallerandagent.create-link-tocreatesadirectedlinkfromthecallertoagent.create-link-fromcreatesadirectedlinkfromagenttothecaller.

Whenthepluralformofthebreednameisused,anagentsetisexpectedinsteadofanagentandlinksarecreatedbetweenthecallerandallagentsintheagentset.

Theoptionalcommandblockisthesetofcommandseachnewlyformedlinkruns.(Thelinksarecreatedallatoncethenrunoneatatime,inrandomorder.)

Anodecannotbelinkedtoitself.Also,youcannothavemorethanoneundirectedlinkofthesamebreedbetweenthesametwonodes,norcanyouhavemorethanonedirectedlinkofthesamebreedgoinginthesamedirectionbetweentwonodes.

Ifyoutrytocreatealinkwhereone(ofthesamebreed)alreadyexists,nothinghappens.Ifyoutrytocreatealinkfromaturtletoitselfyougetaruntimeerror.

to setup clear-all create-turtles 5 ;; turtle 1 creates links with all other turtles ;; the link between the turtle and itself is ignored ask turtle 0 [ create-links-with other turtles ] show count links ;; shows 4 ;; this does nothing since the link already exists ask turtle 0 [ create-link-with turtle 1 ] show count links ;; shows 4 since the previous link already existed ask turtle 2 [ create-link-with turtle 1 ] show count links ;; shows 5end

directed-link-breed [red-links red-link]undirected-link-breed [blue-links blue-link]

to setup clear-all create-turtles 5 ;; create links in both directions between turtle 0 ;; and all other turtles ask turtle 0 [ create-red-links-to other turtles ] ask turtle 0 [ create-red-links-from other turtles ] show count links ;; shows 8 ;; now create undirected links between turtle 0 and other turtles ask turtle 0 [ create-blue-links-with other turtles ] show count links ;; shows 12end

create-turtlescrt

create-turtlesnumbercreate-turtlesnumber[commands]create-<breeds>numbercreate-<breeds>number[commands]

Createsnumbernewturtlesattheorigin.Newturtleshaverandomintegerheadingsandthecolorisrandomlyselectedfromthe14primarycolors.

Ifthecreate-<breeds>formisused,thenewturtlesarecreatedasmembersofthegivenbreed.

Ifcommandsaresupplied,thenewturtlesimmediatelyrunthem.Thisisusefulforgivingthenewturtlesadifferentcolor,heading,orwhatever.(Thenewturtlesarecreatedallatoncethenrunoneatatime,inrandomorder.)

crt 100 [ fd 10 ] ;; makes a randomly spaced circle

breed [canaries canary]breed [snakes snake]to setup clear-all create-canaries 50 [ set color yellow ] create-snakes 50 [ set color green ]end

Seealsohatch,sprout.

create-temporary-plot-pen

create-temporary-plot-penstring

Anewtemporaryplotpenwiththegivennameiscreatedinthecurrentplotandsettobethecurrentpen.

Fewmodelswillwanttousethisprimitive,becausealltemporarypensdisappearwhenclear-plotorclear-all-plotsarecalled.Thenormalwaytomakeapenistomakeapermanentpenintheplot'sEditdialog.

Ifapenwiththatnamealreadyexistsinthecurrentplot,nonewpeniscreated,andtheexistingpenissettothecurrentpen.

Thenewtemporaryplotpenhasthefollowinginitialsettings:

Since3.0

Since1.0

Since1.0

Since1.0

Pen:downColor:blackMode:0(linemode)Interval:1

See:clear-plot,clear-all-plots,andset-current-plot-pen.

D

date-and-time

date-and-time

Reportsastringcontainingthecurrentdateandtime.Theformatisshownbelow.Allfieldsarefixedwidth,sotheyarealwaysatthesamelocationsinthestring.Thepotentialresolutionoftheclockismilliseconds.(Whetheryougetresolutionthathighinpracticemayvaryfromsystemtosystem,dependingonthecapabilitiesoftheunderlyingJavaVirtualMachine.)

show date-and-time=> "01:19:36.685 PM 19-Sep-2002"

die

die

Theturtleorlinkdies.

if xcor > 20 [ die ];; all turtles with xcor greater than 20 dieask links with [color = blue] [ die ];; all the blue links will die

Adeadagentceasestoexist.Theeffectsofthisinclude:

Theagentwillnotexecuteanyfurthercode.Soifyouwriteask turtles [ die print "last words?" ] ,nolastwordswillbeprinted,becausetheturtlesarealreadydeadbeforetheyhaveachancetoprintanything.Theagentwilldisappearfromanyagentsetsitwasin,reducingthesizeofthoseagentsetsbyone.Anyvariablethatwasstoringtheagentwillnowinsteadhavenobodyinit.Soforexamplelet x one-of turtles ask x [ die ] print xprintsnobody.Ifthedeadagentwasaturtle,everylinkconnectedtoitalsodies.Iftheobserverwaswatchingorfollowingtheagent,theobserver'sperspectiveresets,asifreset-perspectivehadbeenrun.

Seealso:clear-turtlesclear-links

diffuse

diffusepatch-variablenumber

Tellseachpatchtogiveequalsharesof(number*100)percentofthevalueofpatch-variabletoitseightneighboringpatches.numbershouldbebetween0and1.Regardlessoftopologythesumofpatch-variablewillbeconservedacrosstheworld.(Ifapatchhasfewerthaneightneighbors,eachneighborstillgetsaneighthshare;thepatchkeepsanyleftovershares.)

Notethatthisisanobservercommandonly,eventhoughyoumightexpectittobeapatchcommand.(Thereasonisthatitactsonallthepatchesatonce--patchcommandsactonindividualpatches.)

diffuse chemical 0.5;; each patch diffuses 50% of its variable;; chemical to its neighboring 8 patches. Thus,;; each patch gets 1/8 of 50% of the chemical;; from each neighboring patch.)

diffuse4

diffuse4patch-variablenumber

Likediffuse,butonlydiffusestothefourneighboringpatches(tothenorth,south,east,andwest),nottothediagonalneighbors.

diffuse4 chemical 0.5;; each patch diffuses 50% of its variable;; chemical to its neighboring 4 patches. Thus,;; each patch gets 1/4 of 50% of the chemical;; from each neighboring patch.)

directed-link-breed

directed-link-breed[<link-breeds><link-breed>]

Thiskeyword,liketheglobalsandbreedskeywords,canonlybeusedatthebeginningoftheCodetab,beforeanyproceduredefinitions.It

Since1.0

Since1.0

Since1.0

definesadirectedlinkbreed.LinksofaparticularbreedarealwaysalldirectedorallundirectedThefirstinputdefinesthenameoftheagentsetassociatedwiththelinkbreed.Thesecondinputdefinesthenameofasinglememberofthebreed.Directedlinkscanbecreatedusingcreate-link(s)-to,andcreate-link(s)-from,butnotcreate-link(s)-with

Anylinkofthegivenlinkbreed:

ispartoftheagentsetnamedbythelinkbreednamehasitsbuilt-invariablebreedsettothatagentsetisdirectedorundirectedasdeclaredbythekeyword

Mostoften,theagentsetisusedinconjunctionwithasktogivecommandstoonlythelinksofaparticularbreed.

directed-link-breed [streets street]directed-link-breed [highways highway]to setup clear-all crt 2 ;; create a link from turtle 0 to turtle 1 ask turtle 0 [ create-street-to turtle 1 ] ;; create a link from turtle 1 to turtle 0 ask turtle 0 [ create-highway-from turtle 1 ]end

ask turtle 0 [ show one-of my-in-links ];; prints (street 0 1)ask turtle 0 [ show one-of my-out-links ];; prints (highway 1 0)

Seealsobreed,undirected-link-breed

display

display

Causestheviewtobeupdatedimmediately.(Exception:iftheuserisusingthespeedslidertofast-forwardthemodel,thentheupdatemaybeskipped.)

Alsoundoestheeffectoftheno-displaycommand,sothatifviewupdatesweresuspendedbythatcommand,theywillresume.

no-displayask turtles [ jump 10 set color blue set size 5 ]display;; turtles move, change color, and grow, with none of;; their intermediate states visible to the user, only;; their final state

Evenifno-displaywasnotused,"display"canstillbeuseful,becauseordinarilyNetLogoisfreetoskipsomeviewupdates,sothatfewertotalupdatestakeplace,sothatmodelsrunfaster.Thiscommandletsyouforceaviewupdate,sowhateverchangeshavetakenplaceintheworldarevisibletotheuser.

ask turtles [ set color red ]displayask turtles [ set color blue];; turtles turn red, then blue; use of "display" forces;; red turtles to appear briefly

Notethatdisplayandno-displayoperateindependentlyoftheswitchintheviewcontrolstripthatfreezestheview.

Seealsono-display.

distance

distanceagent

Reportsthedistancefromthisagenttothegiventurtleorpatch.

Thedistancetoorafromapatchismeasuredfromthecenterofthepatch.Turtlesandpatchesusethewrappeddistance(aroundtheedgesoftheworld)ifwrappingisallowedbythetopologyandthewrappeddistanceisshorter.

ask turtles [ show max-one-of turtles [distance myself] ];; each turtle prints the turtle farthest from itself

distancexy

distancexyxy

Reportsthedistancefromthisagenttothepoint(x,y).

Thedistancefromapatchismeasuredfromthecenterofthepatch.Turtlesandpatchesusethewrappeddistance(aroundtheedgesoftheworld)ifwrappingisallowedbythetopologyandthewrappeddistanceisshorter.

if (distancexy 0 0) > 10 [ set color green ];; all turtles more than 10 units from;; the center of the world turn green.

Since1.0Since1.0

Since1.0Since1.0

Since1.0

Since4.0

Since4.0

downhilldownhill4

downhillpatch-variabledownhill4patch-variable

Movestheturtletotheneighboringpatchwiththelowestvalueforpatch-variable.Ifnoneighboringpatchhasasmallervaluethanthecurrentpatch,theturtlestaysput.Iftherearemultiplepatcheswiththesamelowestvalue,theturtlepicksonerandomly.Non-numericvaluesareignored.

downhillconsiderstheeightneighboringpatches;downhill4onlyconsidersthefourneighbors.

Equivalenttothefollowingcode(assumesvariablevaluesarenumeric):

move-to patch-here ;; go to patch centerlet p min-one-of neighbors [patch-variable] ;; or neighbors4if [patch-variable] of p < patch-variable [ face p move-to p]

Notethattheturtlealwaysendsuponapatchcenterandhasaheadingthatisamultipleof45(downhill)or90(downhill4).

Seealsouphill,uphill4.

dxdy

dxdy

Reportsthex-incrementory-increment(theamountbywhichtheturtle'sxcororycorwouldchange)iftheturtleweretotakeonestepforwardinitscurrentheading.

Note:dxissimplythesineoftheturtle'sheading,anddyissimplythecosine.(Ifthisisthereverseofwhatyouexpected,it'sbecauseinNetLogoaheadingof0isnorthand90iseast,whichisthereverseofhowanglesareusuallydefinedingeometry.)

Note:InearlierversionsofNetLogo,theseprimitiveswereusedinmanysituationswherethenewpatch-aheadprimitiveisnowmoreappropriate.

E

empty?

empty?listempty?string

Reportstrueifthegivenlistorstringisempty,falseotherwise.

Note:theemptylistiswritten[].Theemptystringiswritten"".

end

end

Usedtoconcludeaprocedure.Seetoandto-report.

end1

end1

Thisisabuilt-inlinkvariable.Itindicatesthefirstendpoint(turtle)ofalink.Fordirectedlinksthiswillalwaysbethesourceforundirectedlinksitwillalwaysbetheturtlewiththelowerwhonumber.Youcannotsetend1.

crt 2ask turtle 0[ create-link-to turtle 1 ]ask links[ show end1 ] ;; shows turtle 0

end2

end2

Thisisabuilt-inlinkvariable.Itindicatesthesecondendpoint(turtle)ofalink.Fordirectedlinksthiswillalwaysbethedestinationforundirectedlinksitwillalwaysbetheturtlewiththehigherwhonumber.Youcannotsetend2.

Since5.0

Since2.1

Since1.0

Since1.0


Since1.2.1Since1.0

crt 2ask turtle 1[ create-link-with turtle 0 ]ask links[ show end2 ] ;; shows turtle 1

error

errorvalue

Causesaruntimeerrortooccur.

Thegivenvalueisconvertedtoastring(ifitisn'tonealready)andusedastheerrormessage.

Seealsoerror-message,carefully.

error-message

error-message

Reportsastringdescribingtheerrorthatwassuppressedbycarefully.

Thisreportercanonlybeusedinthesecondblockofacarefullycommand.

Seealsoerror,carefully.

every

everynumber[commands]

Runsthegivencommandsonlyifit'sbeenmorethannumbersecondssincethelasttimethisagentrantheminthiscontext.Otherwise,thecommandsareskipped.

Byitself,everydoesn'tmakecommandsrunoverandoveragain.Youneedtouseeveryinsidealoop,orinsideaforeverbutton,ifyouwantthecommandsrunoverandoveragain.everyonlylimitshowoftenthecommandsrun.

Above,"inthiscontext"meansduringthesameask(orbuttonpressorcommandtypedintheCommandCenter).Soitdoesn'tmakesensetowriteask turtles [ every 0.5 [ ... ] ],becausewhentheaskfinishestheturtleswillalldiscardtheirtimersforthe"every".Thecorrectusageisshownbelow.

every 0.5 [ ask turtles [ fd 1 ] ];; twice a second the turtles will move forward 1every 2 [ set index index + 1 ];; every 2 seconds index is incremented

Seealsowait.

exp

expnumber

Reportsthevalueoferaisedtothenumberpower.

Note:Thisisthesamease^number.

export-viewexport-interfaceexport-outputexport-plotexport-all-plotsexport-world

export-viewfilenameexport-interfacefilenameexport-outputfilenameexport-plotplotnamefilenameexport-all-plotsfilenameexport-worldfilename

export-viewwritesthecurrentcontentsofthecurrentviewtoanexternalfilegivenbythestringfilename.ThefileissavedinPNG(PortableNetworkGraphics)format,soitisrecommendedtosupplyafilenameendingin".png".

export-interfaceissimilar,butforthewholeinterfacetab.

Notethatexport-viewstillworkswhenrunningNetLogoinheadlessmode,butexport-interfacedoesn't.

export-outputwritesthecontentsofthemodel'soutputareatoanexternalfilegivenbythestringfilename.(Ifthemodeldoesnothaveaseparateoutputarea,theoutputportionoftheCommandCenterisused.)

export-plotwritesthexandyvaluesofallpointsplottedbyalltheplotpensintheplotgivenbythestringplotnametoanexternalfilegivenbythestringfilename.Ifapenisinbarmode(mode0)andtheyvalueofthepointplottedisgreaterthan0,theupper-leftcornerpointofthebar

Since1.0

Since1.0

Since3.0

willbeexported.Iftheyvalueislessthan0,thenthelower-leftcornerpointofthebarwillbeexported.

export-all-plotswriteseveryplotinthecurrentmodeltoanexternalfilegivenbythestringfilename.Eachplotisidenticalinformattotheoutputofexport-plot.

export-worldwritesthevaluesofallvariables,bothbuilt-inanduser-defined,includingallobserver,turtle,andpatchvariables,thedrawing,thecontentsoftheoutputareaifoneexists,thecontentsofanyplotsandthestateoftherandomnumbergenerator,toanexternalfilegivenbythestringfilename.(TheresultfilecanbereadbackintoNetLogowiththeimport-worldprimitive.)export-worlddoesnotsavethestateofopenfiles.

export-plot,export-all-plotsandexport-worldsavefilesininplain-text,"comma-separatedvalues"(.csv)format.CSVfilescanbereadbymostpopularspreadsheetanddatabaseprogramsaswellasanytexteditor.

Ifyouwishtoexporttoafileinalocationotherthanthemodel'slocation,youshouldincludethefullpathtothefileyouwishtoexport.(Usetheforward-slash"/"asthefolderseparator.)

NotethatthefunctionalityoftheseprimitivesisalsoavailabledirectlyfromNetLogo'sFilemenu.

export-world "fire.csv";; exports the state of the model to the file fire.csv;; located in the NetLogo folderexport-plot "Temperature" "c:/My Documents/plot.csv";; exports the plot named;; "Temperature" to the file plot.csv located in;; the C:\My Documents folderexport-all-plots "c:/My Documents/plots.csv";; exports all plots to the file plots.csv;; located in the C:\My Documents folder

Ifthefilealreadyexists,itisoverwritten.Toavoidthisyoumaywishtousesomemethodofgeneratingfreshnames.Examples:

export-world user-new-fileexport-world (word "results " date-and-time ".csv") ;; Colon characters in the time cause errors on Windowsexport-world (word "results " random-float 1.0 ".csv")

extensions

extensions[name...]

Allowsthemodeltouseprimitivesfromtheextensionswiththegivennames.SeetheExtensionsguideformoreinformation.

extract-hsb

extract-hsbcolor

Reportsalistofthreevalues,thefirst(hue)intherangeof0to360,thesecondandthird(brightnessandsaturation)intherangeof0to100.

ThegivencolorcaneitherbeaNetLogocolorintherange0to140,notincluding140itself,oranRGBlistofthreevaluesintherange0to255representingthelevelsofred,green,andblue.

show extract-hsb cyan=> [180 57.143 76.863]show extract-hsb red=> [3.103 80.93 84.314]show extract-hsb [255 0 0]=> [0 100 100]

Seealsoapproximate-hsb,approximate-rgb,extract-rgb.

extract-rgb

extract-rgbcolor

Reportsalistofthreevaluesintherange0to255representingthelevelsofred,green,andblue,respectively,ofthegivenNetLogocolorintherange0to140,notincluding140itself.

show extract-rgb red=> [215 50 41]show extract-rgb cyan=> [84 196 196]

Seealsoapproximate-rgb,approximate-hsb,extract-hsb.

F

face

faceagent

Setthecaller'sheadingtowardsagent.

Ifwrappingisallowedbythetopologyandthewrappeddistance(aroundtheedgesoftheworld)isshorter,facewillusethewrappedpath.

Since3.0

Since2.0

Since2.0

Since2.0

Since2.0

Since2.0

Since4.0

Ifthecallerandtheagentareattheexactsameposition,thecaller'sheadingwon'tchange.

facexy

facexyxy

Setthecaller'sheadingtowardsthepoint(x,y).

Ifwrappingisallowedbythetopologyandthewrappeddistance(aroundtheedgesoftheworld)isshorterandwrappingisallowed,facexywillusethewrappedpath.

Ifthecallerisonthepoint(x,y),thecaller'sheadingwon'tchange.

file-at-end?

file-at-end?

Reportstruewhentherearenomorecharacterslefttoreadinfromthecurrentfile(thatwasopenedpreviouslywithfile-open).Otherwise,reportsfalse.

file-open "my-file.txt"print file-at-end?=> false ;; Can still read in more charactersprint file-read-line=> This is the last line in fileprint file-at-end?=> true ;; We reached the end of the file

Seealsofile-open,file-close-all.

file-close

file-close

Closesafilethathasbeenopenedpreviouslywithfile-open.

Notethatthisandfile-close-allaretheonlywaystorestarttothebeginningofanopenedfileortoswitchbetweenfilemodes.

Ifnofileisopen,doesnothing.

Seealsofile-close-all,file-open.

file-close-all

file-close-all

Closesallfiles(ifany)thathavebeenopenedpreviouslywithfile-open.

Seealsofile-close,file-open.

file-delete

file-deletestring

Deletesthefilespecifiedasstring

stringmustbeanexistingfilewithwritablepermissionbytheuser.Also,thefilecannotbeopen.Usethecommandfile-closetocloseanopenedfilebeforedeletion.

Notethatthestringcaneitherbeafilenameoranabsolutefilepath.Ifitisafilename,itlooksinwhateverthecurrentdirectoryis.Thiscanbechangedusingthecommandset-current-directory.Itisdefaultedtothemodel'sdirectory.

file-exists?

file-exists?string

Reportstrueifstringisthenameofanexistingfileonthesystem.Otherwiseitreportsfalse.

Notethatthestringcaneitherbeafilenameoranabsolutefilepath.Ifitisafilename,itlooksinwhateverthecurrentdirectoryis.Thiscanbechangedusingthecommandset-current-directory.Itdefaultstotothemodel'sdirectory.

file-flush

file-flush

Forcesfileupdatestobewrittentodisk.Whenyouusefile-writeorotheroutputcommands,thevaluesmaynotbeimmediatelywrittentodisk.Thisimprovestheperformanceofthefileoutputcommands.Closingafileensuresthatalloutputiswrittentodisk.

Sometimesyouneedtoensurethatdataiswrittentodiskwithoutclosingthefile.Forexample,youcouldbeusingafiletocommunicatewithanotherprogramonyourmachineandwanttheotherprogramtobeabletoseetheoutputimmediately.

Since2.0

Since2.0

Since2.0

Since2.0

file-open

file-openstring

Thiscommandwillinterpretstringasapathnametoafileandopenthefile.Youmaythenusethereportersfile-read,file-read-line,andfile-read-characterstoreadinfromthefile,orfile-write,file-print,file-type,orfile-showtowriteouttothefile.

Notethatyoucanonlyopenafileforreadingorwritingbutnotboth.Thenextfilei/oprimitiveyouuseafterthiscommanddictateswhichmodethefileisopenedin.Toswitchmodes,youneedtoclosethefileusingfile-close.

Also,thefilemustalreadyexistifopeningafileinreadingmode.

Whenopeningafileinwritingmode,allnewdatawillbeappendedtotheendoftheoriginalfile.Ifthereisnooriginalfile,anewblankfilewillbecreatedinitsplace.(Youmusthavewritepermissioninthefile'sdirectory.)(Ifyoudon'twanttoappend,butwanttoreplacethefile'sexistingcontents,usefile-deletetodeleteitfirst,perhapsinsideacarefullyifyou'renotsurewhetheritalreadyexists.)

Notethatthestringcaneitherbeafilenameoranabsolutefilepath.Ifitisafilename,itlooksinwhateverthecurrentdirectoryis.Thiscanbechangedusingthecommandset-current-directory.Itisdefaultedtothemodel'sdirectory.

file-open "my-file-in.txt"print file-read-line=> First line in file ;; File is in reading modefile-open "C:\\NetLogo\\my-file-out.txt";; assuming Windows machinefile-print "Hello World" ;; File is in writing mode

Openingafiledoesnotclosepreviouslyopenedfiles.Youcanusefile-opentoswitchbackandforthbetweenmultipleopenfiles.

Seealsofile-closeSeealsofile-close-all.

file-print

file-printvalue

Printsvaluetoanopenedfile,followedbyacarriagereturn.

Thisagentisnotprintedbeforethevalue,unlikefile-show.

Notethatthiscommandisthefilei/oequivalentofprint,andfile-openneedstobecalledbeforethiscommandcanbeused.

Seealsofile-show,file-type,andfile-write.

file-read

file-read

ThisreporterwillreadinthenextconstantfromtheopenedfileandinterpretitasifithadbeentypedintheCommandCenter.Itreportstheresultingvalue.Theresultmaybeanumber,list,string,boolean,orthespecialvaluenobody.

Whitespaceseparatestheconstants.Eachcalltofile-readwillskippastbothleadingandtrailingwhitespace.

Notethatstringsneedtohavequotesaroundthem.Usethecommandfile-writetohavequotesincluded.

Alsonotethatthefile-opencommandmustbecalledbeforethisreportercanbeused,andtheremustbedataremaininginthefile.Usethereporterfile-at-end?todetermineifyouareattheendofthefile.

file-open "my-file.data"print file-read + 5;; Next value is the number 1=> 6print length file-read;; Next value is the list [1 2 3 4]=> 4

Seealsofile-openandfile-write.

file-read-characters

file-read-charactersnumber

Reportsthegivennumberofcharactersfromanopenedfileasastring.Iftherearefewerthanthatmanycharactersleft,itwillreportalloftheremainingcharacters.

Notethatitwillreturneverycharacterincludingnewlinesandspaces.


file-open "my-file.txt"print file-read-characters 5;; Current line in file is "Hello World"=> Hello

Seealsofile-open.

Since2.0

Since2.0

Since2.0

Since2.0

Since1.3

Since1.0

file-read-line

file-read-line

Readsthenextlineinthefileandreportsitasastring.Itdeterminestheendofthefilebyacarriagereturn,anendoffilecharacterorbothinarow.Itdoesnotreturnthelineterminatorcharacters.


file-open "my-file.txt"print file-read-line=> Hello World

Seealsofile-open.

file-show

file-showvalue

Printsvaluetoanopenedfile,precededbythisagentagent,andfollowedbyacarriagereturn.(Thisagentisincludedtohelpyoukeeptrackofwhatagentsareproducingwhichlinesofoutput.)Also,allstringshavetheirquotesincludedsimilartofile-write.

Notethatthiscommandisthefilei/oequivalentofshow,andfile-openneedstobecalledbeforethiscommandcanbeused.

Seealsofile-print,file-type,andfile-write.

file-type

file-typevalue

Printsvaluetoanopenedfile,notfollowedbyacarriagereturn(unlikefile-printandfile-show).Thelackofacarriagereturnallowsyoutoprintseveralvaluesonthesameline.

Thisagentisnotprintedbeforethevalue.unlikefile-show.

Notethatthiscommandisthefilei/oequivalentoftype,andfile-openneedstobecalledbeforethiscommandcanbeused.

Seealsofile-print,file-show,andfile-write.

file-write

file-writevalue

Thiscommandwilloutputvalue,whichcanbeanumber,string,list,boolean,ornobodytoanopenedfile,notfollowedbyacarriagereturn(unlikefile-printandfile-show).

Thisagentisnotprintedbeforethevalue,unlikefile-show.Itsoutputalsoincludesquotesaroundstringsandisprependedwithaspace.Itwilloutputthevalueinsuchamannerthatfile-readwillbeabletointerpretit.

Notethatthiscommandisthefilei/oequivalentofwrite,andfile-openneedstobecalledbeforethiscommandcanbeused.

file-open "locations.txt"ask turtles [ file-write xcor file-write ycor ]

Seealsofile-print,file-show,andfile-type.

filter

filterreporterlist

Reportsalistcontainingonlythoseitemsoflistforwhichthereporterreportstrue--inotherwords,theitemssatisfyingthegivencondition.reportermaybeananonymousreporterorthenameofareporter.

show filter is-number? [1 "2" 3]=> [1 3]show filter [ i -> i < 3 ] [1 3 2]=> [1 2]show filter [ s -> first s != "t" ] ["hi" "there" "everyone"]=> ["hi" "everyone"]

Seealsomap,reduce,->(anonymousprocedure).

first

firstlistfirststring

Onalist,reportsthefirst(0th)iteminthelist.

Since1.0

Since3.0

Since3.0

Since1.3

Since1.0Since1.0

Onastring,reportsaone-characterstringcontainingonlythefirstcharacteroftheoriginalstring.

floor

floornumber

Reportsthelargestintegerlessthanorequaltonumber.

show floor 4.5=> 4show floor -4.5=> -5

Seealsoceiling,round,precision.

follow

followturtle

Similartoride,but,inthe3Dview,theobserver'svantagepointisbehindandaboveturtle.

Theobservermayonlywatchorfollowasinglesubject.Callingfollowwillalterthehighlightcreatedbypriorcallstowatchandwatch-me,highlightingthefollowedturtleinstead.

Seealsofollow-me,ride,reset-perspective,watch,subject.

follow-me

follow-me

Askstheobservertofollowthisturtle.

Theobservermayonlywatchorfollowasinglesubject.Callingfollow-mewillremovethehighlightcreatedbypriorcallstowatchandwatch-me,highlightingthisturtleinstead.

Seealsofollow.

foreach

foreachlistcommand(foreachlist1...command)

Withasinglelist,runsthecommandforeachitemoflist.commandmaybethenameofacommand,orananonymouscommandcreatedwith->.

foreach [1.1 2.2 2.6] show=> 1.1=> 2.2=> 2.6foreach [1.1 2.2 2.6] [ x -> show (word x " -> " round x) ]=> 1.1 -> 1=> 2.2 -> 2=> 2.6 -> 3

Withmultiplelists,runscommandforeachgroupofitemsfromeachlist.So,theyarerunonceforthefirstitems,oncefortheseconditems,andsoon.Allthelistsmustbethesamelength.

Someexamplesmakethisclearer:

(foreach [1 2 3] [2 4 6] [ [a b] -> show word "the sum is: " (a + b) ])=> "the sum is: 3"=> "the sum is: 6"=> "the sum is: 9"(foreach list (turtle 1) (turtle 2) [3 4] [ [the-turtle num-steps] -> ask the-turtle [ fd num-steps ] ]);; turtle 1 moves forward 3 patches;; turtle 2 moves forward 4 patches

Seealsomap,->(anonymousprocedure).

forwardfd

forwardnumber

Theturtlemovesforwardbynumbersteps,onestepatatime.(Ifnumberisnegative,theturtlemovesbackward.)

fd 10isequivalenttorepeat 10 [ jump 1 ] .fd 10.5isequivalenttorepeat 10 [ jump 1 ] jump 0.5.

Iftheturtlecannotmoveforwardnumberstepsbecauseitisnotpermittedbythecurrenttopologytheturtlewillcompleteasmanystepsof1

Since1.0

Since1.0

asitcan,thenstop.

Seealsojump,can-move?.

fput

fputitemlist

Addsitemtothebeginningofalistandreportsthenewlist.

;; suppose mylist is [5 7 10]set mylist fput 2 mylist;; mylist is now [2 5 7 10]

G

globals

globals[var1...]

Thiskeyword,likethebreed,<breeds>-own,patches-own,andturtles-ownkeywords,canonlybeusedatthebeginningofaprogram,beforeanyfunctiondefinitions.Itdefinesnewglobalvariables.Globalvariablesare"global"becausetheyareaccessiblebyallagentsandcanbeusedanywhereinamodel.

Mostoften,globalsisusedtodefinevariablesorconstantsthatneedtobeusedinmanypartsoftheprogram.

H

hatch

hatchnumber[commands]hatch-<breeds>number[commands]

Thisturtlecreatesnumbernewturtles.Eachnewturtleinheritsofallitsvariables,includingitslocation,fromitsparent.(Exceptions:eachnewturtlewillhaveanewwhonumber,anditmaybeofadifferentbreedthanitsparentifthehatch-<breeds>formisused.)

Thenewturtlesthenruncommands.Youcanusethecommandstogivethenewturtlesdifferentcolors,headings,locations,orwhatever.(Thenewturtlesarecreatedallatonce,thenrunoneatatime,inrandomorder.)

Ifthehatch-<breeds>formisused,thenewturtlesarecreatedasmembersofthegivenbreed.Otherwise,thenewturtlesarethesamebreedastheirparent.

hatch 1 [ lt 45 fd 1 ];; this turtle creates one new turtle,;; and the child turns and moves awayhatch-sheep 1 [ set color black ];; this turtle creates a new turtle;; of the sheep breed

Seealsocreate-turtles,sprout.

heading

heading

Thisisabuilt-inturtlevariable.Itindicatesthedirectiontheturtleisfacing.Thisisanumbergreaterthanorequalto0andlessthan360.0isnorth,90iseast,andsoon.Youcansetthisvariabletomakeaturtleturn.

Seealsoright,left,dx,dy.

Example:

set heading 45 ;; turtle is now facing northeastset heading heading + 10 ;; same effect as "rt 10"

hidden?

hidden?

Thisisabuilt-inturtleorlinkvariable.Itholdsaboolean(trueorfalse)valueindicatingwhethertheturtleorlinkiscurrentlyhidden(i.e.,invisible).Youcansetthisvariabletomakeaturtleorlinkdisappearorreappear.

Seealsohide-turtle,show-turtle,hide-link,show-link

Example:

Since4.0

Since1.0Since1.0

Since1.0

Since1.0

Since1.0

Since1.1

Since4.1

set hidden? not hidden?;; if turtle was showing, it hides, and if it was hiding,;; it reappears

hide-link

hide-link

Thelinkmakesitselfinvisible.

Note:Thiscommandisequivalenttosettingthelinkvariable"hidden?"totrue.

Seealsoshow-link.

hide-turtleht

hide-turtle

Theturtlemakesitselfinvisible.

Note:Thiscommandisequivalenttosettingtheturtlevariable"hidden?"totrue.

Seealsoshow-turtle.

histogram

histogramlist

Histogramsthevaluesinthegivenlist

Drawsahistogramshowingthefrequencydistributionofthevaluesinthelist.Theheightsofthebarsinthehistogramrepresentthenumbersofvaluesineachsubrange.

Beforethehistogramisdrawn,firstanypreviouspointsdrawnbythecurrentplotpenareremoved.

Anynon-numericvaluesinthelistareignored.

Thehistogramisdrawnonthecurrentplotusingthecurrentplotpenandpencolor.Autoscalingdoesnotaffectahistogram'shorizontalrange,soset-plot-x-rangeshouldbeusedtocontroltherange,andthepenintervalcanthenbeset(eitherdirectlywithset-plot-pen-interval,orindirectlyviaset-histogram-num-bars)tocontrolhowmanybarsthatrangeissplitupinto.

Besurethatifyouwantthehistogramdrawnwithbarsthatthecurrentpenisinbarmode(mode1).

Forhistogrammingpurposestheplot'sXrangeisnotconsideredtoincludethemaximumXvalue.ValuesequaltothemaximumXwillfalloutsideofthehistogram'srange.

histogram [color] of turtles;; draws a histogram showing how many turtles there are;; of each color

home

home

Thisturtlemovestotheorigin(0,0).Equivalenttosetxy 0 0.

hsb

hsbhuesaturationbrightness

ReportsaRGBlistwhengiventhreenumbersdescribinganHSBcolor.Hue,saturation,andbrightnessareintegersintherange0-360,0-100,0-100respectively.TheRGBlistcontainsthreeintegersintherangeof0-255.

Seealsorgb

hubnet-broadcast

hubnet-broadcasttag-namevalue

ThisbroadcastsvaluefromNetLogototheinterfaceelementwiththenametag-nameontheclients.

SeetheHubNetAuthoringGuidefordetailsandinstructions.

hubnet-broadcast-clear-output

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hubnet-broadcast-clear-output

Thisclearsallmessagesprintedtothetextareaoneveryclient.

Seealso:hubnet-broadcast-message,hubnet-send-clear-output

hubnet-broadcast-message

hubnet-broadcast-messagevalue

Thisprintsthevalueinthetextareaoneachclient.Thisisthesamefunctionalityasthe"BroadcastMessage"buttonintheHubNetControlCenter.

Seealso:hubnet-send-message

hubnet-clear-overridehubnet-clear-overrides

hubnet-clear-overrideclientagent-or-setvariable-namehubnet-clear-overridesclient

Removeoverridesfromtheoverridelistonclient.hubnet-clear-overrideremovesonlytheoverrideforthespecifiedvariableforthespecifiedagentoragentset.hubnet-clear-overridesremovesalloverridesfromthespecifiedclient.

Seealso:hubnet-send-override

hubnet-clients-list

hubnet-clients-list

ReportsalistcontainingthenamesofalltheclientscurrentlyconnectedtotheHubNetserver.

hubnet-enter-message?

hubnet-enter-message?

Reportstrueifanewclientjustenteredthesimulation.Reportsfalseotherwise.hubnet-message-sourcewillcontaintheusernameoftheclientthatjustloggedon.


hubnet-exit-message?

hubnet-exit-message?

Reportstrueifaclientjustexitedthesimulation.Reportsfalseotherwise.hubnet-message-sourcewillcontaintheusernameoftheclientthatjustloggedoff.


hubnet-fetch-message

hubnet-fetch-message

Ifthereisanynewdatasentbytheclients,thisretrievesthenextpieceofdata,sothatitcanbeaccessedbyhubnet-message,hubnet-message-source,andhubnet-message-tag.Thiswillcauseanerrorifthereisnonewdatafromtheclients.

SeetheHubNetAuthoringGuidefordetails.

hubnet-kick-client

hubnet-kick-clientclient-name

Kickstheclientwiththegivenclient-name.ThisisequivalenttoclickingtheclientnameintheHubNetControlCenterandpressingtheKickbutton.

hubnet-kick-all-clients

hubnet-kick-all-clients

KicksoutallcurrentlyconnectedHubNetclients.ThisisequivalenttoselectingallclientsintheHubNetControlCenterandpressingtheKickbutton.

hubnet-message

hubnet-message

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Since4.1

Reportsthemessageretrievedbyhubnet-fetch-message.


hubnet-message-source

hubnet-message-source

Reportsthenameoftheclientthatsentthemessageretrievedbyhubnet-fetch-message.


hubnet-message-tag

hubnet-message-tag

Reportsthetagthatisassociatedwiththedatathatwasretrievedbyhubnet-fetch-message.ThetagwillbeoneoftheDisplayNamesoftheinterfaceelementsintheclientinterface.


hubnet-message-waiting?

hubnet-message-waiting?

Thislooksforanewmessagesentbytheclients.Itreportstrueifthereisone,andfalseifthereisnot.


hubnet-reset

hubnet-reset

StartsuptheHubNetsystem.HubNetmustbestartedtouseanyoftheotherhubnetprimitives.


hubnet-reset-perspective

hubnet-reset-perspectivetag-name

Clearswatchorfollowsentdirectlytotheclient.Theviewperspectivewillreverttotheserverperspective.

Seealso:hubnet-send-watchhubnet-send-follow

hubnet-send

hubnet-sendstringtag-namevalue

hubnet-sendlist-of-stringstag-namevalue

Forastring,thissendsvaluefromNetLogotothetagtag-nameontheclientthathasstringforitsusername.

Foralist-of-strings,thissendsvaluefromNetLogotothetagtag-nameonalltheclientsthathaveausernamethatisinthelist-of-strings.

Sendingamessagetoanon-existentclient,usinghubnet-send,generatesahubnet-exit-message.


hubnet-send-clear-output

hubnet-send-clear-outputstring

hubnet-send-clear-outputlist-of-strings

Thisclearsallmessagesprintedtothetextareaonthegivenclientorclients(specifiedinthestringorlist-of-strings.

Seealso:hubnet-send-message,hubnet-broadcast-clear-output

hubnet-send-follow

hubnet-send-followclient-nameagentradius

Tellstheclientassociatedwithclient-nametofollowagentshowingaradiussizedMooreneighborhoodaroundtheagent.

Aclientmayonlywatchorfollowasinglesubject.Callinghubnet-send-followwillalterthehighlightcreatedbypriorcallstohubnet-send-watch,highlightingthefollowedagentinstead.

Seealso:hubnet-send-watch,hubnet-reset-perspective

Since4.1

Since4.1

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hubnet-send-message

hubnet-send-messagestringvalue

Thisprintsvalueinthetextareaontheclientspecifiedbystring.

Seealso:hubnet-broadcast-message

hubnet-send-override

hubnet-send-overrideclient-nameagent-or-setvariable-name[reporter]

Evaluatesreporterfortheagentoragentsetindicatedthensendsthevaluestotheclientto"override"thevalueofvariable-nameonlyonclient-name.Thisisusedtochangetheappearanceofagentsintheclientview,hence,onlybuilt-invariablesthataffecttheappearanceoftheagentmaybeselected.Forexample,youcanoverridethecolorvariableofaturtle:

ask turtles [ hubnet-send-override client-name self "color" [ red ] ]

Inthisexampleassumethatthereisaturtles-ownvariableclient-namewhichisassociatedwithaloggedinclient,andalltheturtlesareblue.Thiscodemakestheturtleassociatedwitheachclientappearredinhisorherownviewbutnotonanyoneelse'sorontheserver.

Seealso:hubnet-clear-overrides

hubnet-send-watch

hubnet-send-watchclient-nameagent

Tellstheclientassociatedwithclient-nametowatchagent.

Aclientmayonlywatchorfollowasinglesubject.Callinghubnet-send-watchwillundoperspectivechangescausedbypriorcallstohubnet-send-follow.

Seealso:hubnet-send-follow,hubnet-reset-perspective

I

if

ifcondition[commands]

Reportermustreportaboolean(trueorfalse)value.

Ifconditionreportstrue,runscommands.

Thereportermayreportadifferentvaluefordifferentagents,sosomeagentsmayruncommandsandothersdon't.

if xcor > 0[ set color blue ];; turtles in the right half of the world;; turn blue

Seealsoifelse,ifelse-value.

ifelse

ifelsereporter[commands1][commands2]


Ifreporterreportstrue,runscommands1.

Ifreporterreportsfalse,runscommands2.

Thereportermayreportadifferentvaluefordifferentagents,sosomeagentsmayruncommands1whileothersruncommands2.

ask patches [ ifelse pxcor > 0 [ set pcolor blue ] [ set pcolor red ] ];; the left half of the world turns red and;; the right half turns blue

Seealsoif,ifelse-value.

ifelse-value

ifelse-valuereporter[reporter1][reporter2]


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Since3.0

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Ifreporterreportstrue,theresultisthevalueofreporter1.

Ifreporterreportsfalse,theresultisthevalueofreporter2.

Thiscanbeusedwhenaconditionalisneededinthecontextofareporter,wherecommands(suchasifelse)arenotallowed.

ask patches [ set pcolor ifelse-value (pxcor > 0) [blue] [red]];; the left half of the world turns red and;; the right half turns blueshow n-values 10 [ifelse-value (? < 5) [0] [1]]=> [0 0 0 0 0 1 1 1 1 1]show reduce [ [a b] -> ifelse-value (a > b) [a] [b] ] [1 3 2 5 3 8 3 2 1]=> 8

Seealsoif,ifelse.

import-drawing

import-drawingfilename

Readsanimagefileintothedrawing,scalingittothesizeoftheworld,whileretainingtheoriginalaspectratiooftheimage.Theimageiscenteredinthedrawing.Theolddrawingisnotclearedfirst.

Agentscannotsensethedrawing,sotheycannotinteractwithorprocessimagesimportedbyimport-drawing.Ifyouneedagentstosenseanimage,useimport-pcolorsorimport-pcolors-rgb.

Thefollowingimagefileformatsaresupported:BMP,JPG,GIF,andPNG.Iftheimageformatsupportstransparency(alpha),thatinformationwillbeimportedaswell.

import-pcolors

import-pcolorsfilename

Readsanimagefile,scalesittothesamedimensionsasthepatchgridwhilemaintainingtheoriginalaspectratiooftheimage,andtransferstheresultingpixelcolorstothepatches.Theimageiscenteredinthepatchgrid.Theresultingpatchcolorsmaybedistorted,sincetheNetLogocolorspacedoesnotincludeallpossiblecolors.(SeetheColorsectionoftheProgrammingGuide.)import-pcolorsmaybeslowforsomeimages,particularlywhenyouhavemanypatchesandalargeimagewithmanydifferentcolors.

Sinceimport-pcolorssetsthepcolorofpatches,agentscansensetheimage.Thisisusefulifagentsneedtoanalyze,process,orotherwiseinteractwiththeimage.Ifyouwanttosimplydisplayastaticbackdrop,withoutcolordistortion,seeimport-drawing.

Thefollowingimagefileformatsaresupported:BMP,JPG,GIF,andPNG.Iftheimageformatsupportstransparency(alpha),thenallfullytransparentpixelswillbeignored.(Partiallytransparentpixelswillbetreatedasopaque.)

import-pcolors-rgb

import-pcolors-rgbfilename

Readsanimagefile,scalesittothesamedimensionsasthepatchgridwhilemaintainingtheoriginalaspectratiooftheimage,andtransferstheresultingpixelcolorstothepatches.Theimageiscenteredinthepatchgrid.Unlikeimport-pcolorstheexactcolorsintheoriginalimageareretained.ThepcolorvariableofallthepatcheswillbeanRGBlistratherthanan(approximated)NetLogocolor.

Thefollowingimagefileformatsaresupported:BMP,JPG,GIF,andPNG.Iftheimageformatsupportstransparency(alpha),thenallfullytransparentpixelswillbeignored.(Partiallytransparentpixelswillbetreatedasopaque.)

import-world

import-worldfilename

Readsthevaluesofallvariablesforamodel,bothbuilt-inanduser-defined,includingallobserver,turtle,andpatchvariables,fromanexternalfilenamedbythegivenstring.Thefileshouldbeintheformatusedbytheexport-worldprimitive.

NotethatthefunctionalityofthisprimitiveisalsodirectlyavailablefromNetLogo'sFilemenu.

Whenusingimport-world,toavoiderrors,performthesestepsinthefollowingorder:

1. Openthemodelfromwhichyoucreatedtheexportfile.2. PresstheSetupbutton,togetthemodelinastatefromwhichitcanberun.3. Importthefile.4. Re-openanyfilesthatthemodelhadopenedwiththefile-opencommand.5. Ifyouwant,pressGobuttontocontinuerunningthemodelfromthepointwhereitleftoff.

Ifyouwishtoimportafilefromalocationotherthanthemodel'slocation,youmayincludethefullpathtothefileyouwishtoimport.Seeexport-worldforanexample.

in-cone

Since4.0

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Since4.0

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Since1.0

agentsetin-conedistanceangle

Thisreporterletsyougiveaturtlea"coneofvision"infrontofitself.Theconeisdefinedbythetwoinputs,thevisiondistance(radius)andtheviewingangle.Theviewinganglemayrangefrom0to360andiscenteredaroundtheturtle'scurrentheading.(Iftheangleis360,thenin-coneisequivalenttoin-radius.)

in-conereportsanagentsetthatincludesonlythoseagentsfromtheoriginalagentsetthatfallinthecone.(Thiscanincludetheagentitself.)

Thedistancetoapatchismeasuredfromthecenterofthepatch.

ask turtles [ ask patches in-cone 3 60 [ set pcolor red ] ];; each turtle makes a red "splotch" of patches in a 60 degree;; cone of radius 3 ahead of itself

in-<breed>-neighbor?in-link-neighbor?

in-<breed>-neighbor?agentin-link-neighbor?turtle

Reportstrueifthereisadirectedlinkgoingfromturtletothecalleroranundirectedlinkconnectingturtletothecaller.Youcanthinkofthisas"istherealinkIcanusetogetfromturtletothecaller?"

crt 2ask turtle 0 [ create-link-to turtle 1 show in-link-neighbor? turtle 1 ;; prints false show out-link-neighbor? turtle 1 ;; prints true]ask turtle 1 [ show in-link-neighbor? turtle 0 ;; prints true show out-link-neighbor? turtle 0 ;; prints false]

in-<breed>-neighborsin-link-neighbors

in-<breed>-neighborsin-link-neighbors

Reportstheagentsetofalltheturtlesthathavedirectedlinkscomingfromthemtothecalleraswellasallturtlesthathaveanundirectedlinkconnectingthemwiththecaller.Youcanthinkofthisas"alltheturtlesthatcangettothecallerusingalink."

crt 4ask turtle 0 [ create-links-to other turtles ]ask turtle 1 [ ask in-link-neighbors [ set color blue ] ] ;; turtle 0 turns blue

in-<breed>-fromin-link-from

in-<breed>-fromturtlein-link-fromturtle

Reportsadirectedlinkfromturtletothecalleroranundirectedlinkconnectingthetwo.Ifnolinkexiststhenitreportsnobody.Ifmorethanonesuchlinkexists,reportsarandomone.Youcanthinkofthisas"givemealinkthatIcanusetotravelfromturtletothecaller."

crt 2ask turtle 0 [ create-link-to turtle 1 ]ask turtle 1 [ show in-link-from turtle 0 ] ;; shows link 0 1ask turtle 0 [ show in-link-from turtle 1 ] ;; shows nobody

Seealso:out-link-tolink-with

__includes

__includes[filename...]

CausesexternalNetLogosourcefiles(withthe.nlssuffix)tobeincludedinthismodel.Includedfilesmaycontainbreed,variable,andproceduredefinitions.__includescanonlybeusedonceperfile.

in-radius

agentsetin-radiusnumber

Since6.0.2

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Since4.0Since1.0

Since1.2.1Since4.0Since4.0

Reportsanagentsetthatincludesonlythoseagentsfromtheoriginalagentsetwhosedistancefromthecallerislessthanorequaltonumber.(Thiscanincludetheagentitself.)

Thedistancetoorafromapatchismeasuredfromthecenterofthepatch.

ask turtles [ ask patches in-radius 3 [ set pcolor red ] ];; each turtle makes a red "splotch" around itself

insert-item

insert-itemindexlistvalueinsert-itemindexstring1string2

Onalist,insertsaniteminthatlist.indexistheindexwheretheitemwillbeinserted.Thefirstitemhasanindexof0.(The6thiteminalistwouldhaveanindexof5.)

Likewiseforastring,butallcharactersinamultiple-characterstring2areinsertedatindex.

show insert-item 2 [2 7 4 5] 15=> [2 7 15 4 5]show insert-item 2 "cat" "re"=> "caret"

inspect

inspectagent

Opensanagentmonitorforthegivenagent(turtleorpatch).

inspect patch 2 4;; an agent monitor opens for that patchinspect one-of sheep;; an agent monitor opens for a random turtle from;; the "sheep" breed

Seestop-inspectingandstop-inspecting-dead-agents

int

intnumber

Reportstheintegerpartofnumber--anyfractionalpartisdiscarded.

show int 4.7=> 4show int -3.5=> -3

is-agent?is-agentset?is-anonymous-command?is-anonymous-reporter?is-boolean?is-directed-link?is-link?is-link-set?is-list?is-number?is-patch?is-patch-set?is-string?is-turtle?is-turtle-set?is-undirected-link?

is-agent?valueis-agentset?valueis-anonymous-command?valueis-anonymous-reporter?valueis-boolean?valueis-<breed>?valueis-<link-breed>?valueis-directed-link?valueis-link?valueis-link-set?valueis-list?value

Since1.0

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is-number?valueis-patch?valueis-patch-set?valueis-string?valueis-turtle?valueis-turtle-set?valueis-undirected-link?value

Reportstrueifvalueisofthegiventype,falseotherwise.

item

itemindexlistitemindexstring

Onlists,reportsthevalueoftheiteminthegivenlistwiththegivenindex.

Onstrings,reportsthecharacterinthegivenstringatthegivenindex.

Notethattheindicesbeginfrom0,not1.(Thefirstitemisitem0,theseconditemisitem1,andsoon.)

;; suppose mylist is [2 4 6 8 10]show item 2 mylist=> 6show item 3 "my-shoe"=> "s"

J

jump

jumpnumber

Theturtlemovesforwardbynumberunitsallatonce(ratherthanonestepatatimeaswiththeforwardcommand).

Iftheturtlecannotjumpnumberunitsbecauseitisnotpermittedbythecurrenttopologytheturtledoesnotmoveatall.

Seealsoforward,can-move?.

L

label

label

Thisisabuilt-inturtleorlinkvariable.Itmayholdavalueofanytype.Theturtleorlinkappearsintheviewwiththegivenvalue"attached"toitastext.Youcansetthisvariabletoadd,change,orremoveaturtleorlink'slabel.

Seealsolabel-color,plabel,plabel-color.

Example:

ask turtles [ set label who ];; all the turtles now are labeled with their;; who numbersask turtles [ set label "" ];; all turtles now are not labeled

label-color

label-color

Thisisabuilt-inturtleorlinkvariable.Itholdsanumbergreaterthanorequalto0andlessthan140.Thisnumberdetermineswhatcolortheturtleorlink'slabelappearsin(ifithasalabel).Youcansetthisvariabletochangethecolorofaturtleorlink'slabel.

Seealsolabel,plabel,plabel-color.

Example:

ask turtles [ set label-color red ];; all the turtles now have red labels

last

lastlistlaststring

Since4.0

Since4.0

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Since4.0

Onalist,reportsthelastiteminthelist.

Onastring,reportsaone-characterstringcontainingonlythelastcharacteroftheoriginalstring.

layout-circle

layout-circleagentsetradiuslayout-circlelist-of-turtlesradius

Arrangesthegiventurtlesinacirclecenteredonthepatchatthecenteroftheworldwiththegivenradius.(Iftheworldhasanevensizethecenterofthecircleisroundeddowntothenearestpatch.)Theturtlespointoutwards.

Ifthefirstinputisanagentset,theturtlesarearrangedinrandomorder.

Ifthefirstinputisalist,theturtlesarearrangedclockwiseinthegivenorder,startingatthetopofthecircle.(Anynon-turtlesinthelistareignored.)

;; in random orderlayout-circle turtles 10;; in order by who numberlayout-circle sort turtles 10;; in order by sizelayout-circle sort-by [ [a b] -> [size] of a < [size] of b ] turtles 10

layout-radial

layout-radialturtle-setlink-setroot-agent

Arrangestheturtlesinturtle-setconnectedbylinksinlink-set,inaradialtreelayout,centeredaroundtheroot-agentwhichismovedtothecenteroftheworldview.

Onlylinksinthelink-setwillbeusedtodeterminethelayout.Iflinksconnectturtlesthatarenotinturtle-setthoseturtleswillremainstationary.

Evenifthenetworkdoescontaincycles,andisnotatruetreestructure,thislayoutwillstillwork,althoughtheresultswillnotalwaysbepretty.

to make-a-tree set-default-shape turtles "circle" crt 6 ask turtle 0 [ create-link-with turtle 1 create-link-with turtle 2 create-link-with turtle 3 ] ask turtle 1 [ create-link-with turtle 4 create-link-with turtle 5 ] ; do a radial tree layout, centered on turtle 0 layout-radial turtles links (turtle 0)end

layout-spring

layout-springturtle-setlink-setspring-constantspring-lengthrepulsion-constant

Arrangestheturtlesinturtle-set,asifthelinksinlink-setarespringsandtheturtlesarerepellingeachother.Turtlesthatareconnectedbylinksinlink-setbutnotincludedinturtle-setaretreatedasanchorsandarenotmoved.

spring-constantisameasureofthe"tautness"ofthespring.Itisthe"resistance"tochangeintheirlength.spring-constantistheforcethespringwouldexertifit'slengthwerechangedby1unit.

spring-lengthisthe"zero-force"lengthorthenaturallengthofthesprings.Thisisthelengthwhichallspringstrytoachieveeitherbypushingouttheirnodesorpullingthemin.

repulsion-constantisameasureofrepulsionbetweenthenodes.Itistheforcethat2nodesatadistanceof1unitwillexertoneachother.

Therepulsioneffecttriestogetthenodesasfaraspossiblefromeachother,inordertoavoidcrowdingandthespringeffecttriestokeepthemat"about"acertaindistancefromthenodestheyareconnectedto.Theresultisthelayingoutofthewholenetworkinawaywhichhighlightsrelationshipsamongthenodesandatthesametimeiscrowdedlessandisvisuallypleasing.

ThelayoutalgorithmisbasedontheFruchterman-Reingoldlayoutalgorithm.Moreinformationaboutthisalgorithmcanbeobtainedhere.

to make-a-triangle set-default-shape turtles "circle" crt 3 ask turtle 0 [ create-links-with other turtles ] ask turtle 1 [ create-link-with turtle 2 ] repeat 30 [ layout-spring turtles links 0.2 5 1 ] ;; lays the nodes in a triangleend

layout-tutte

http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.13.8444

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layout-tutteturtle-setlink-setradius

Theturtlesthatareconnectedbylinksinlink-setbutnotincludedinturtle-setareplacedinacirclelayoutwiththegivenradius.Thereshouldbeatleast3agentsinthisagentset.

Theturtlesinturtle-setarethenlaidoutinthefollowingmanner:Eachturtleisplacedatcentroid(orbarycenter)ofthepolygonformedbyitslinkedneighbors.(Thecentroidislikea2-dimensionalaverageofthecoordinatesoftheneighbors.)

(Thepurposeofthecircleof"anchoragents"istopreventalltheturtlesfromcollapsingdowntoonepoint.)

Afterafewiterationsofthis,thelayoutwillstabilize.

ThislayoutisnamedafterthemathematicianWilliamThomasTutte,whoproposeditasamethodforgraphlayout.

to make-a-tree set-default-shape turtles "circle" crt 6 ask turtle 0 [ create-link-with turtle 1 create-link-with turtle 2 create-link-with turtle 3 ] ask turtle 1 [ create-link-with turtle 4 create-link-with turtle 5 ] ; place all the turtles with just one ; neighbor on the perimeter of a circle ; and then place the remaining turtles inside ; this circle, spread between their neighbors. repeat 10 [ layout-tutte (turtles with [link-neighbors = 1]) links 12 ]end

leftlt

leftnumber

Theturtleturnsleftbynumberdegrees.(Ifnumberisnegative,itturnsright.)

length

lengthlistlengthstring

Reportsthenumberofitemsinthegivenlist,orthenumberofcharactersinthegivenstring.

let

letvariablevalue

Createsanewlocalvariableandgivesitthegivenvalue.Alocalvariableisonethatexistsonlywithintheenclosingblockofcommands.

Ifyouwanttochangethevalueafterwards,useset.

Example:

let prey one-of sheep-hereif prey != nobody [ ask prey [ die ] ]

link

linkend1end2<breed>end1end2

Giventhewhonumbersoftheendpoints,reportsthelinkconnectingtheturtles.Ifthereisnosuchlinkreportsnobody.Torefertobreededlinksyoumustusethesingularbreedformwiththeendpoints.

ask link 0 1 [ set color green ];; unbreeded link connecting turtle 0 and turtle 1 will turn greenask directed-link 0 1 [ set color red ];; directed link connecting turtle 0 and turtle 1 will turn red

Seealsopatch-at.

link-heading

link-heading

Reportstheheadingindegrees(atleast0,lessthan360)fromend1toend2ofthelink.Throwsaruntimeerroriftheendpointsareatthesamelocation.

Since4.0

Since4.0

Since4.0

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Since1.0

ask link 0 1 [ print link-heading ];; prints [[towards other-end] of end1] of link 0 1

Seealsolink-length

link-length

link-length

Reportsthedistancebetweentheendpointsofthelink.

ask link 0 1 [ print link-length ];; prints [[distance other-end] of end1] of link 0 1

Seealsolink-heading

link-set

link-setvalue(link-setvalue1value2...)

Reportsanagentsetcontainingallofthelinksanywhereinanyoftheinputs.Theinputsmaybeindividuallinks,linkagentsets,nobody,orlists(ornestedlists)containinganyoftheabove.

link-set selflink-set [my-links] of nodes with [color = red]

Seealsoturtle-set,patch-set.

link-shapes

link-shapes

Reportsalistofstringscontainingallofthelinkshapesinthemodel.

Newshapescanbecreated,orimportedfromothermodels,intheLinkShapesEditor.

show link-shapes=> ["default"]

links

links

Reportstheagentsetconsistingofalllinks.

show count links;; prints the number of links

links-own

links-own[var1...]<link-breeds>-own[var1...]

Thelinks-ownkeyword,liketheglobals,breed,<breeds>-own,turtles-own,andpatches-ownkeywords,canonlybeusedatthebeginningofaprogram,beforeanyfunctiondefinitions.Itdefinesthevariablesbelongingtoeachlink.

Ifyouspecifyabreedinsteadof"links",onlylinksofthatbreedhavethelistedvariables.(Morethanonelinkbreedmaylistthesamevariable.)

undirected-link-breed [sidewalks sidewalk]directed-link-breed [streets street]links-own [traffic] ;; applies to all breedssidewalks-own [pedestrians]streets-own [cars bikes]

list

listvalue1value2(listvalue1...)

Reportsalistcontainingthegivenitems.Theitemscanbeofanytype,producedbyanykindofreporter.

show list (random 10) (random 10)=> [4 9] ;; or similar listshow (list 5)

Since1.0

Since1.0

Since1.0

Since1.0

Since1.3

Since1.0

=> [5]show (list (random 10) 1 2 3 (random 10))=> [4 1 2 3 9] ;; or similar list

ln

lnnumber

Reportsthenaturallogarithmofnumber,thatis,thelogarithmtothebasee(2.71828...).

Seealsoe,log.

log

lognumberbase

Reportsthelogarithmofnumberinbasebase.

show log 64 2=> 6

Seealsoln.

loop

loop[commands]

Repeatsthecommandsforever,oruntiltheenclosingprocedureexitsthroughuseofthestoporreportcommands.

to move-to-world-edge ;; turtle procedure loop [ if not can-move? 1 [ stop ] fd 1 ]end

Inthisexample,stopexitsnotjusttheloop,buttheentireprocedure.

Note:inmanycircumstances,itismoreappropriatetouseaforeverbuttontorepeatsomethingindefinitely.SeeButtonsintheProgrammingGuide.

lput

lputvaluelist

Addsvaluetotheendofalistandreportsthenewlist.

;; suppose mylist is [2 7 10 "Bob"]set mylist lput 42 mylist;; mylist now is [2 7 10 "Bob" 42]

M

map

mapreporterlist(mapreporterlist1...)

Withasinglelist,thegivenreporterisrunforeachiteminthelist,andalistoftheresultsiscollectedandreported.reportermaybeananonymousreporterorthenameofareporter.

show map round [1.1 2.2 2.7]=> [1 2 3]show map [ i -> i * i ] [1 2 3]=> [1 4 9]

Withmultiplelists,thegivenreporterisrunforeachgroupofitemsfromeachlist.So,itisrunonceforthefirstitems,oncefortheseconditems,andsoon.Allthelistsmustbethesamelength.

Someexamplesmakethisclearer:

show (map + [1 2 3] [2 4 6])=> [3 6 9]show (map [ [a b c] -> a + b = c ] [1 2 3] [2 4 6] [3 5 9])=> [true false true]

Seealsoforeach,->(anonymousprocedure).

max

Since4.0

Since1.0

Since3.1Since3.1

Since1.0

Since1.0

maxlist

Reportsthemaximumnumbervalueinthelist.Itignoresothertypesofitems.

show max [xcor] of turtles;; prints the x coordinate of the turtle which is;; farthest right in the worldshow max list a b;; prints the larger of the two variables a and bshow max (list a b c);; prints the largest of the three variables a, b, and c

max-n-of

max-n-ofnumberagentset[reporter]

Reportsanagentsetcontainingnumberagentsfromagentsetwiththehighestvaluesofreporter.Theagentsetisbuiltbyfindingalltheagentswiththehighestvalueofreporter,iftherearenotnumberagentswiththatvaluethenagentswiththesecondhighestvaluearefound,andsoon.Attheend,ifthereisatiethatwouldmaketheresultingagentsettoolarge,thetieisbrokenrandomly.

;; assume the world is 11 x 11show max-n-of 5 patches [pxcor];; shows 5 patches with pxcor = max-pxcorshow max-n-of 5 patches with [pycor = 0] [pxcor];; shows an agentset containing:;; (patch 1 0) (patch 2 0) (patch 3 0) (patch 4 0) (patch 5 0)

Seealsomax-one-of,with-max.

max-one-of

max-one-ofagentset[reporter]

Reportstheagentintheagentsetthathasthehighestvalueforthegivenreporter.Ifthereisatiethiscommandreportsonerandomagentwiththehighestvalue.Ifyouwantallsuchagents,usewith-maxinstead.

show max-one-of patches [count turtles-here]

;; prints the first patch with the most turtles on it

Seealsomax-n-of,with-max.

max-pxcormax-pycor

max-pxcormax-pycor

Thesereportersgivethemaximumx-coordinateandmaximumy-coordinate,(respectively)forpatches,whichdeterminesthesizeoftheworld.

UnlikeinolderversionsofNetLogotheorigindoesnothavetobeatthecenteroftheworld.However,themaximumx-andy-coordinatesmustbegreaterthanorequaltozero.


crt 100 [ setxy random-float max-pxcor random-float max-pycor ];; distributes 100 turtles randomly in the;; first quadrant

Seealsomin-pxcor,min-pycor,world-width,andworld-height

mean

meanlist

Reportsthestatisticalmeanofthenumericitemsinthegivenlist.Errorsonnon-numericitems.Themeanistheaverage,i.e.,thesumoftheitemsdividedbythetotalnumberofitems.

show mean [xcor] of turtles;; prints the average of all the turtles' x coordinates

median

medianlist

Reportsthestatisticalmedianofthenumericitemsofthegivenlist.Ignoresnon-numericitems.Themedianistheitemthatwouldbeinthemiddleifalltheitemswerearrangedinorder.(Iftwoitemswouldbeinthemiddle,themedianistheaverageofthetwo.)

Since1.0

Since1.0

Since4.0

Since1.0

Since3.1Since3.1

show median [xcor] of turtles;; prints the median of all the turtles' x coordinates

member?

member?valuelistmember?string1string2member?agentagentset

Foralist,reportstrueifthegivenvalueappearsinthegivenlist,otherwisereportsfalse.

Forastring,reportstrueorfalsedependingonwhetherstring1appearsanywhereinsidestring2asasubstring.

Foranagentset,reportstrueifthegivenagentisappearsinthegivenagentset,otherwisereportsfalse.

show member? 2 [1 2 3]=> trueshow member? 4 [1 2 3]=> falseshow member? "bat" "abate"=> trueshow member? turtle 0 turtles=> trueshow member? turtle 0 patches=> false

Seealsoposition.

min

minlist

Reportstheminimumnumbervalueinthelist.Itignoresothertypesofitems.

show min [xcor] of turtles;; prints the lowest x-coordinate of all the turtlesshow min list a b;; prints the smaller of the two variables a and bshow min (list a b c);; prints the smallest of the three variables a, b, and c

min-n-of

min-n-ofnumberagentset[reporter]

Reportsanagentsetcontainingnumberagentsfromagentsetwiththelowestvaluesofreporter.Theagentsetisbuiltbyfindingalltheagentswiththelowestvalueofreporter,iftherearenotnumberagentswiththatvaluethentheagentswiththesecondlowestvaluearefound,andsoon.Attheend,ifthereisatiethatwouldmaketheresultingagentsettoolarge,thetieisbrokenrandomly.

;; assume the world is 11 x 11show min-n-of 5 patches [pxcor];; shows 5 patches with pxcor = min-pxcorshow min-n-of 5 patches with [pycor = 0] [pxcor];; shows an agentset containing:;; (patch -5 0) (patch -4 0) (patch -3 0) (patch -2 0) (patch -1 0)

Seealsomin-one-of,with-min.

min-one-of

min-one-ofagentset[reporter]

Reportsarandomagentintheagentsetthatreportsthelowestvalueforthegivenreporter.Ifthereisatie,thiscommandreportsonerandomagentthatmeetsthecondition.Ifyouwantallsuchagentsusewith-mininstead.

show min-one-of turtles [xcor + ycor];; reports the first turtle with the smallest sum of;; coordinates

Seealsowith-min,min-n-of.

min-pxcormin-pycor

min-pxcormin-pycor

Thesereportersgivetheminimumx-coordinateandminimumy-coordinate,(respectively)forpatches,whichdeterminesthesizeoftheworld.

UnlikeinolderversionsofNetLogotheorigindoesnothavetobeatthecenteroftheworld.However,theminimumx-andy-coordinatesmustbelessthanorequaltozero.


Since1.0

Since2.0

Since1.0

Since3.0

Since1.0Since1.0

Since4.0

crt 100 [ setxy random-float min-pxcor random-float min-pycor ];; distributes 100 turtles randomly in the;; third quadrant

Seealsomax-pxcor,max-pycor,world-width,andworld-height

mod

number1modnumber2

Reportsnumber1modulonumber2:thatis,theresidueofnumber1(modnumber2).modisisequivalenttothefollowingNetLogocode:

number1 - (floor (number1 / number2)) * number2

Notethatmodis"infix",thatis,itcomesbetweenitstwoinputs.

show 62 mod 5=> 2show -8 mod 3=> 1

Seealsoremainder.modandremainderbehavethesameforpositivenumbers,butdifferentlyfornegativenumbers.

modes

modeslist

Reportsalistofthemostcommonitemoritemsinlist.

TheinputlistmaycontainanyNetLogovalues.

Iftheinputisanemptylist,reportsanemptylist.

show modes [1 2 2 3 4]=> [2]show modes [1 2 2 3 3 4]=> [2 3]show modes [ [1 2 [3]] [1 2 [3]] [2 3 4] ]=> [[1 2 [3]]]show modes [pxcor] of turtles;; shows which columns of patches have the most;; turtles on them

mouse-down?

mouse-down?

Reportstrueifthemousebuttonisdown,falseotherwise.

Note:Ifthemousepointerisoutsideofthecurrentview,mouse-down?willalwaysreportfalse.

mouse-inside?

mouse-inside?

Reportstrueifthemousepointerisinsidethecurrentview,falseotherwise.

mouse-xcormouse-ycor

mouse-xcormouse-ycor

Reportsthexorycoordinateofthemouseinthe2Dview.Thevalueisintermsofturtlecoordinates,soitmightnotbeaninteger.Ifyouwantpatchcoordinates,useround mouse-xcorandround mouse-ycor.

Note:Ifthemouseisoutsideofthe2Dview,reportsthevaluefromthelasttimeitwasinside.

;; to make the mouse "draw" in red:if mouse-down? [ ask patch mouse-xcor mouse-ycor [ set pcolor red ] ]

move-to

move-toagent

Theturtlesetsitsxandycoordinatestobethesameasthegivenagent's.

Since4.0

Since4.0

Since4.0

Since1.0

(Ifthatagentisapatch,theeffectistomovetheturtletothecenterofthatpatch.)

move-to turtle 5;; turtle moves to same point as turtle 5move-to one-of patches;; turtle moves to the center of a random patchmove-to max-one-of turtles [size];; turtle moves to same point as biggest turtle

Notethattheturtle'sheadingisunaltered.Youmaywanttousethefacecommandfirsttoorienttheturtleinthedirectionofmotion.

Seealsosetxy.

my-<breeds>my-links

my-<breeds>my-links

Reportsanagentsetofalllinksconnectedtothecallerofthecorrespondingbreed,regardlessofdirectedness.Generally,youmightconsiderusingmy-out-linksinsteadofthisprimitive,asitworkswellforeitherdirectedorundirectednetworks(sinceitexcludesdirected,incominglinks).

crt 5ask turtle 0[ create-links-with other turtles show my-links ;; prints the agentset containing all links ;; (since all the links we created were with turtle 0 )]ask turtle 1[ show my-links ;; shows an agentset containing the link 0 1]end

Ifyouonlywanttheundirectedlinksconnectedtoanode,youcandomy-links with [ not is-directed-link? self ].

my-in-<breeds>my-in-links

my-in-<breeds>my-in-links

Reportsanagentsetofallthedirectedlinkscominginfromothernodestothecalleraswellasallundirectedlinksconnectedtothecaller.Youcanthinkofthisas"alllinksthatyoucanusetotraveltothisnode".

crt 5ask turtle 0[ create-links-to other turtles show my-in-links ;; shows an empty agentset]ask turtle 1[ show my-in-links ;; shows an agentset containing the link 0 1]

my-out-<breeds>my-out-links

my-out-<breeds>my-out-links

Reportsanagentsetofallthedirectedlinksgoingoutfromthecallertoothernodesaswellasundirectedlinksconnectedtothecaller.Youcanthinkofthisas"alllinksyoucanusetotravelfromthisnode".

crt 5ask turtle 0[ create-links-to other turtles show my-out-links ;; shows agentset containing all the links]ask turtle 1[ show my-out-links ;; shows an empty agentset]

myself

myself

"self"and"myself"areverydifferent."self"issimple;itmeans"me"."myself"means"theturtle,patchorlinkwhoaskedmetodowhatI'm

Since3.1

Since2.0

Since1.1Since1.1

Since4.0

doingrightnow."

Whenanagenthasbeenaskedtorunsomecode,usingmyselfinthatcodereportstheagent(turtle,patchorlink)thatdidtheasking.

myselfismostoftenusedinconjunctionwithoftoreadorsetvariablesintheaskingagent.

myselfcanbeusedwithinblocksofcodenotjustintheaskcommand,butalsohatch,sprout,of,with,all?,with-min,with-max,min-one-of,max-one-of,min-n-of,max-n-of.

ask turtles [ ask patches in-radius 3 [ set pcolor [color] of myself ] ];; each turtle makes a colored "splotch" around itself

Seethe"MyselfExample"codeexampleformoreexamples.

Seealsoself.

N

n-of

n-ofsizeagentsetn-ofsizelist

Fromanagentset,reportsanagentsetofsizesizerandomlychosenfromtheinputset,withnorepeats.

Fromalist,reportsalistofsizesizerandomlychosenfromtheinputset,withnorepeats.Theitemsintheresultappearinthesameorderthattheyappearedintheinputlist.(Ifyouwanttheminrandomorder,useshuffleontheresult.)

Itisanerrorforsizetobegreaterthanthesizeoftheinput.

ask n-of 50 patches [ set pcolor green ];; 50 randomly chosen patches turn green

Seealsoone-of.

n-values

n-valuessizereporter

Reportsalistoflengthsizecontainingvaluescomputedbyrepeatedlyrunningthereporter.reportermaybeananonymousreporterorthenameofareporter.

Ifthereporteracceptsinputs,theinputwillbethenumberoftheitemcurrentlybeingcomputed,startingfromzero.

show n-values 5 [1]=> [1 1 1 1 1]show n-values 5 [ i -> i ]=> [0 1 2 3 4]show n-values 3 turtle=> [(turtle 0) (turtle 1) (turtle 2)]show n-values 5 [ x -> x * x ]=> [0 1 4 9 16]

Seealsoreduce,filter,->(anonymousprocedure),range.

neighborsneighbors4

neighborsneighbors4

Reportsanagentsetcontainingthe8surroundingpatches(neighbors)or4surroundingpatches(neighbors4).

show sum [count turtles-here] of neighbors ;; prints the total number of turtles on the eight ;; patches around this turtle or patchshow count turtles-on neighbors ;; a shorter way to say the same thingask neighbors4 [ set pcolor red ] ;; turns the four neighboring patches red

<breed>-neighborslink-neighbors

<breed>-neighborslink-neighbors

Reportstheagentsetofallturtlesfoundattheotherendofanylinks(undirectedordirected,incomingoroutgoing)connectedtothisturtle.

Since4.0

Since3.0

Since5.2

Since3.0

Since1.0

crt 3ask turtle 0[ create-links-with other turtles ask link-neighbors [ set color red ] ;; turtles 1 and 2 turn red]ask turtle 1[ ask link-neighbors [ set color blue ] ;; turtle 0 turns blue]end

<breed>-neighbor?link-neighbor?

<breed>-neighbor?turtlelink-neighbor?turtle

Reportstrueifthereisalink(eitherdirectedorundirected,incomingoroutgoing)betweenturtleandthecaller.

crt 2ask turtle 0[ create-link-with turtle 1 show link-neighbor? turtle 1 ;; prints true]ask turtle 1[ show link-neighbor? turtle 0 ;; prints true]

netlogo-version

netlogo-version

ReportsastringcontainingtheversionnumberoftheNetLogoyouarerunning.

show netlogo-version=> "6.0.2"

netlogo-web?

netlogo-web?

ReportstrueifthemodelisrunninginNetLogoWeb.

new-seed

new-seed

Reportsanumbersuitableforseedingtherandomnumbergenerator.

Thenumbersreportedbynew-seedarebasedonthecurrentdateandtimeinmillisecondsandlieinthegenerator'susablerangeofseeds,-2147483648to2147483647.

new-seedneverreportsthesamenumbertwiceinsuccession,evenacrossparallelBehaviorSpaceruns.(Thisisaccomplishedbywaitingamillisecondiftheseedforthecurrentmillisecondwasalreadyused.)

Seealsorandom-seed.

no-display

no-display

Turnsoffallupdatestothecurrentviewuntilthedisplaycommandisissued.Thishastwomajoruses.

One,youcancontrolwhentheuserseesviewupdates.Youmightwanttochangelotsofthingsontheviewbehindtheuser'sback,sotospeak,thenmakethemvisibletotheuserallatonce.

Two,yourmodelwillrunfasterwhenviewupdatingisoff,soifyou'reinahurry,thiscommandwillletyougetresultsfaster.(Notethatnormallyyoudon'tneedtouseno-displayforthis,sinceyoucanalsousetheon/offswitchinviewcontrolstriptofreezetheview.)

Notethatdisplayandno-displayoperateindependentlyoftheswitchintheviewcontrolstripthatfreezestheview.

Seealsodisplay.

nobody

nobody

Thisisaspecialvaluewhichsomeprimitivessuchasturtle,one-of,max-one-of,etc.reporttoindicatethatnoagentwasfound.Also,whenaturtledies,itbecomesequaltonobody.

Since4.0

Since4.0

Since1.0

Since4.0

Since4.0

Since1.0

Note:Emptyagentsetsarenotequaltonobody.Ifyouwanttotestforanemptyagentset,useany?.Youonlygetnobodybackinsituationswhereyouwereexpectingasingleagent,notawholeagentset.

set target one-of other turtles-hereif target != nobody [ ask target [ set color red ] ]

no-links

no-links

Reportsanemptylinkagentset.

no-patches

no-patches

Reportsanemptypatchagentset.

not

notboolean

Reportstrueifbooleanisfalse,otherwisereportsfalse.

if not any? turtles [ crt 10 ]

no-turtles

no-turtles

Reportsanemptyturtleagentset.

O

of

[reporter]ofagent[reporter]ofagentset

Foranagent,reportsthevalueofthereporterforthatagent(turtleorpatch).

show [pxcor] of patch 3 5;; prints 3show [pxcor] of one-of patches;; prints the value of a random patch's pxcor variableshow [who * who] of turtle 5=> 25show [count turtles in-radius 3] of patch 0 0;; prints the number of turtles located within a;; three-patch radius of the origin

Foranagentset,reportsalistthatcontainsthevalueofthereporterforeachagentintheagentset(inrandomorder).

crt 4show sort [who] of turtles=> [0 1 2 3]show sort [who * who] of turtles=> [0 1 4 9]

one-of

one-ofagentsetone-oflist

Fromanagentset,reportsarandomagent.Iftheagentsetisempty,reportsnobody.

Fromalist,reportsarandomlistitem.Itisanerrorforthelisttobeempty.

ask one-of patches [ set pcolor green ];; a random patch turns greenask patches with [any? turtles-here] [ show one-of turtles-here ];; for each patch containing turtles, prints one of;; those turtles

;; suppose mylist is [1 2 3 4 5 6]show one-of mylist;; prints a value randomly chosen from the list

Seealson-of.

Since1.0

Since4.0

Since4.0

Since4.0

Since4.0

or

boolean1orboolean2

Reportstrueifeitherboolean1orboolean2,orboth,istrue.

Notethatifcondition1istrue,thencondition2willnotberun(sinceitcan'taffecttheresult).

if (pxcor > 0) or (pycor > 0) [ set pcolor red ];; patches turn red except in lower-left quadrant

other

otheragentset

Reportsanagentsetwhichisthesameastheinputagentsetbutomitsthisagent.

show count turtles-here=> 10show count other turtles-here=> 9

other-end

other-end

Ifrunbyaturtle,reportstheturtleattheotherendoftheaskinglink.

Ifrunbyalink,reportstheturtleattheendofthelinkthatisn'ttheaskingturtle.

Thesedefinitionsaredifficulttounderstandintheabstract,butthefollowingexamplesshouldhelp:

ask turtle 0 [ create-link-with turtle 1 ]ask turtle 0 [ ask link 0 1 [ show other-end ] ] ;; prints turtle 1ask turtle 1 [ ask link 0 1 [ show other-end ] ] ;; prints turtle 0ask link 0 1 [ ask turtle 0 [ show other-end ] ] ;; prints turtle 1

Astheseexampleshopefullymakeplain,the"other"endistheendthatisneitheraskingnorbeingasked.

out-<breed>-neighbor?out-link-neighbor?

out-<breed>-neighbor?turtleout-link-neighbor?turtle

Reportstrueifthereisadirectedlinkgoingfromthecallertoturtleorifthereisanundirectedlinkconnectingthecallerwithturtle.Youcanthinkofthisas"canIgetfromthecallertoturtleusingalink?"

crt 2ask turtle 0 [ create-link-to turtle 1 show in-link-neighbor? turtle 1 ;; prints false show out-link-neighbor? turtle 1 ;; prints true]ask turtle 1 [ show in-link-neighbor? turtle 0 ;; prints true show out-link-neighbor? turtle 0 ;; prints false]

out-<breed>-neighborsout-link-neighbors

out-<breed>-neighborsout-link-neighbors

Reportstheagentsetofalltheturtlesthathavedirectedlinksfromthecaller,orundirectedlinkswiththecaller.Youcanthinkofthisas"whocanIgettofromthecallerusingalink?"

crt 4ask turtle 0[ create-links-to other turtles ask out-link-neighbors [ set color pink ] ;; turtles 1-3 turn pink]ask turtle 1[ ask out-link-neighbors [ set color orange ] ;; no turtles change colors ;; since turtle 1 only has in-links]end

Since4.0


Since1.0

Since2.0

Since1.0

out-<breed>-toout-link-to

out-<breed>-toturtleout-link-toturtle

Reportsadirectedlinkfromthecallertoturtleoranundirectedlinkconnectingthetwo.Ifnolinkexiststhenitreportsnobody.Ifmorethanonesuchlinkexists,reportsarandomone.Youcanthinkofthisas"givemealinkthatIcanusetotravelfromthecallertoturtle."

crt 2ask turtle 0 [ create-link-to turtle 1 show out-link-to turtle 1 ;; shows link 0 1]ask turtle 1[ show out-link-to turtle 0 ;; shows nobody]

Seealso:in-link-fromlink-with

output-printoutput-showoutput-typeoutput-write

output-printvalueoutput-showvalueoutput-typevalueoutput-writevalue

Thesecommandsarethesameastheprint,show,type,andwritecommandsexceptthatvalueisprintedinthemodel'soutputarea,insteadofintheCommandCenter.(Ifthemodeldoesnothaveaseparateoutputarea,thentheCommandCenterisused.)

P

patch

patchxcorycor

Giventhexandycoordinatesofapoint,reportsthepatchcontainingthatpoint.(Thecoordinatesareabsolutecoordinates;theyarenotcomputedrelativetothisagent,aswithpatch-at.)

Ifxandyareintegers,thepointisthecenterofapatch.Ifxoryisnotaninteger,roundingtothenearestintegerisusedtodeterminewhichpatchcontainsthepoint.

Ifwrappingisallowedbythetopology,thegivencoordinateswillbewrappedtobewithintheworld.Ifwrappingisnotallowedandthegivencoordinatesareoutsidetheworld,reportsnobody.

ask patch 3 -4 [ set pcolor green ];; patch with pxcor of 3 and pycor of -4 turns greenshow patch 1.2 3.7;; prints (patch 1 4); note roundingshow patch 18 19;; supposing min-pxcor and min-pycor are -17;; and max-pxcor and max-pycor are 17,;; in a wrapping topology, prints (patch -17 -16);;; in a non-wrapping topology, prints nobody

Seealsopatch-at.

patch-ahead

patch-aheaddistance

Reportsthesinglepatchthatisthegivendistance"ahead"ofthisturtle,thatis,alongtheturtle'scurrentheading.Reportsnobodyifthepatchdoesnotexistbecauseitisoutsidetheworld.

ask patch-ahead 1 [ set pcolor green ];; turns the patch 1 in front of this turtle;; green; note that this might be the same patch;; the turtle is standing on

Seealsopatch-at,patch-left-and-ahead,patch-right-and-ahead,patch-at-heading-and-distance.

patch-at

patch-atdxdy

Since2.0

Since1.0

Since2.0Since2.0

Since4.0

Since4.1

Reportsthepatchat(dx,dy)fromthecaller,thatis,thepatchcontainingthepointdxeastanddypatchesnorthofthisagent.

Reportsnobodyifthereisnosuchpatchbecausethatpointisbeyondanon-wrappingworldboundary.

ask patch-at 1 -1 [ set pcolor green ];; if caller is a turtle or patch, turns the;; patch just southeast of the caller green

Seealsopatch,patch-ahead,patch-left-and-ahead,patch-right-and-ahead,patch-at-heading-and-distance.

patch-at-heading-and-distance

patch-at-heading-and-distanceheadingdistance

patch-at-heading-and-distancereportsthesinglepatchthatisthegivendistancefromthisturtleorpatch,alongthegivenabsoluteheading.(Incontrasttopatch-left-and-aheadandpatch-right-and-ahead,thisturtle'scurrentheadingisnottakenintoaccount.)Reportsnobodyifthepatchdoesnotexistbecauseitisoutsidetheworld.

ask patch-at-heading-and-distance -90 1 [ set pcolor green ];; turns the patch 1 to the west of this patch green

Seealsopatch,patch-at,patch-left-and-ahead,patch-right-and-ahead.

patch-here

patch-here

patch-herereportsthepatchundertheturtle.

Notethatthisreporterisn'tavailabletoapatchbecauseapatchcanjustsay"self".

patch-left-and-aheadpatch-right-and-ahead

patch-left-and-aheadangledistancepatch-right-and-aheadangledistance

Reportsthesinglepatchthatisthegivendistancefromthisturtle,inthedirectionturnedleftorrightthegivenangle(indegrees)fromtheturtle'scurrentheading.Reportsnobodyifthepatchdoesnotexistbecauseitisoutsidetheworld.

(Ifyouwanttofindapatchinagivenabsoluteheading,ratherthanonerelativetothecurrentturtle'sheading,usepatch-at-heading-and-distanceinstead.)

ask patch-right-and-ahead 30 1 [ set pcolor green ];; this turtle "looks" 30 degrees right of its;; current heading at the patch 1 unit away, and turns;; that patch green; note that this might be the same;; patch the turtle is standing on

Seealsopatch,patch-at,patch-at-heading-and-distance.

patch-set

patch-setvalue1(patch-setvalue1value2...)

Reportsanagentsetcontainingallofthepatchesanywhereinanyoftheinputs.Theinputsmaybeindividualpatches,patchagentsets,nobody,orlists(ornestedlists)containinganyoftheabove.

patch-set selfpatch-set patch-here(patch-set self neighbors)(patch-set patch-here neighbors)(patch-set patch 0 0 patch 1 3 patch 4 -2)(patch-set patch-at -1 1 patch-at 0 1 patch-at 1 1)patch-set [patch-here] of turtlespatch-set [neighbors] of turtles

Seealsoturtle-set,link-set.

patch-size

patch-size

Reportsthesizeofthepatchesintheviewinpixels.Thesizeistypicallyaninteger,butmayalsobeafloatingpointnumber.

Seealsoset-patch-size.

Since1.0


patches

patches

Reportstheagentsetconsistingofallpatches.

patches-own

patches-own[var1...]

Thiskeyword,liketheglobals,breed,<breed>-own,andturtles-ownkeywords,canonlybeusedatthebeginningofaprogram,beforeanyfunctiondefinitions.Itdefinesthevariablesthatallpatchescanuse.

Allpatcheswillthenhavethegivenvariablesandbeabletousethem.

Allpatchvariablescanalsobedirectlyaccessedbyanyturtlestandingonthepatch.

Seealsoglobals,turtles-own,breed,<breeds>-own.

pcolor

pcolor

Thisisabuilt-inpatchvariable.Itholdsthecolorofthepatch.Youcansetthisvariabletomakethepatchchangecolor.

Allpatchvariablescanbedirectlyaccessedbyanyturtlestandingonthepatch.ColorcanberepresentedeitherasaNetLogocolor(asinglenumber)oranRGBcolor(alistof3numbers).SeedetailsintheColorssectionoftheProgrammingGuide.

Seealsocolor.

pen-downpdpen-erasepepen-uppu

pen-downpen-erasepen-up

Theturtlechangesmodesbetweendrawinglines,removinglinesorneither.Thelineswillalwaysbedisplayedontopofthepatchesandbelowtheturtles.Tochangethecolorofthepensetthecoloroftheturtleusingset color.

Note:Whenaturtle'spenisdown,allmovementcommandscauselinestobedrawn,includingjump,setxy,andmove-to.

Note:Thesecommandsareequivalenttosettingtheturtlevariable"pen-mode"to"down","up",and"erase".

Note:OnWindowsdrawinganderasingalinemightnoteraseeverypixel.

pen-mode

Thisisabuilt-inturtlevariable.Itholdsthestateoftheturtle'spen.Yousetthevariabletodrawlines,eraselinesorstopeitheroftheseactions.Possiblevaluesare"up","down",and"erase".

pen-size

Thisisabuilt-inturtlevariable.Itholdsthewidthoftheline,inpixels,thattheturtlewilldraw(orerase)whenthepenisdown(orerasing).

plabel

plabel

Thisisabuilt-inpatchvariable.Itmayholdavalueofanytype.Thepatchappearsintheviewwiththegivenvalue"attached"toitastext.Youcansetthisvariabletoadd,change,orremoveapatch'slabel.


Seealsoplabel-color,label,label-color.

plabel-color

Since1.0

Since1.0

Since4.0

Since1.0Since1.0

Since1.0

Since1.0


Since1.0

plabel-color

Thisisabuilt-inpatchvariable.Itholdsanumbergreaterthanorequalto0andlessthan140.Thisnumberdetermineswhatcolorthepatch'slabelappearsin(ifithasalabel).Youcansetthisvariabletochangethecolorofapatch'slabel.


Seealsoplabel,label,label-color.

plot

plotnumber

Incrementsthex-valueoftheplotpenbyplot-pen-interval,thenplotsapointattheupdatedx-valueanday-valueofnumber.(Thefirsttimethecommandisusedonaplot,thepointplottedhasanx-valueof0.)

plot-name

plot-name

Reportsthenameofthecurrentplot(astring)

plot-pen-exists?

plot-pen-exists?string

Reportstrueifaplotpenwiththegivennameisdefinedinthecurrentplot.Otherwisereportsfalse.

plot-pen-downplot-pen-up

plot-pen-downplot-pen-up

Putsdown(orup)thecurrentplot-pen,sothatitdraws(ordoesn't).(Bydefault,allpensaredowninitially.)

plot-pen-reset

plot-pen-reset

Clearseverythingthecurrentplotpenhasdrawn,movesitto(0,0),andputsitdown.Ifthepenisapermanentpen,thecolor,mode,andintervalareresettothedefaultvaluesfromtheplotEditdialog.

plotxy

plotxynumber1number2

Movesthecurrentplotpentothepointwithcoordinates(number1,number2).Ifthepenisdown,aline,bar,orpointwillbedrawn(dependingonthepen'smode).

plot-x-minplot-x-maxplot-y-minplot-y-max

plot-x-minplot-x-maxplot-y-minplot-y-max

Reportstheminimumormaximumvalueonthexoryaxisofthecurrentplot.

Thesevaluescanbesetwiththecommandsset-plot-x-rangeandset-plot-y-range.(TheirdefaultvaluesaresetfromtheplotEditdialog.)

position

positionitemlistpositionstring1string2

Onalist,reportsthefirstpositionofiteminlist,orfalseifitdoesnotappear.

Onstrings,reportsthepositionofthefirstappearancestring1asasubstringofstring2,orfalseifitdoesnotappear.

Note:Thepositionsarenumberedbeginningwith0,notwith1.

;; suppose mylist is [2 7 4 7 "Bob"]

Since1.0

Since1.0

Since1.0

Since2.0

show position 7 mylist=> 1show position 10 mylist=> falseshow position "in" "string"=> 3

Seealsomember?.

precision

precisionnumberplaces

Reportsnumberroundedtoplacesdecimalplaces.

Ifplacesisnegative,theroundingtakesplacetotheleftofthedecimalpoint.

show precision 1.23456789 3=> 1.235show precision 3834 -3=> 4000

Seealsoround,ceiling,floor.

print

printvalue

PrintsvalueintheCommandCenter,followedbyacarriagereturn.

Thisagentisnotprintedbeforethevalue,unlikeshow.

Seealsoshow,type,andwrite.

Seealsooutput-print.

pxcorpycor

pxcorpycor

Thesearebuilt-inpatchvariables.Theyholdthexandycoordinateofthepatch.Theyarealwaysintegers.Youcannotsetthesevariables,becausepatchesdon'tmove.

pxcorisgreaterthanorequaltomin-pxcorandlessthanorequaltomax-pxcor;similarlyforpycorandmin-pycorandmax-pycor.


Seealsoxcor,ycor.

R

random

randomnumber

Ifnumberispositive,reportsarandomintegergreaterthanorequalto0,butstrictlylessthannumber.

Ifnumberisnegative,reportsarandomintegerlessthanorequalto0,butstrictlygreaterthannumber.

Ifnumberiszero,theresultisalways0aswell.

Note:InversionsofNetLogopriortoversion2.0,thisprimitivereportedafloatingpointnumberifgivenanon-integerinput.Thisisnolongerthecase.Ifyouwantafloatingpointanswer,youmustnowuserandom-floatinstead.

show random 3;; prints 0, 1, or 2show random -3;; prints 0, -1, or -2show random 3.5;; prints 0, 1, 2, or 3

Seealsorandom-float.

random-float

random-floatnumber

Ifnumberispositive,reportsarandomfloatingpointnumbergreaterthanorequalto0butstrictlylessthannumber.

Ifnumberisnegative,reportsarandomfloatingpointnumberlessthanorequalto0,butstrictlygreaterthannumber.

Since1.2.1Since2.0


Since3.1Since3.1

Since1.0

Since3.1Since3.1

Ifnumberiszero,theresultisalways0.

show random-float 3;; prints a number at least 0 but less than 3,;; for example 2.589444906014774show random-float 2.5;; prints a number at least 0 but less than 2.5,;; for example 1.0897423196760796

random-exponentialrandom-gammarandom-normalrandom-poisson

random-exponentialmeanrandom-gammaalphalambdarandom-normalmeanstandard-deviationrandom-poissonmean

Reportsanaccordinglydistributedrandomnumberwiththemeanand,inthecaseofthenormaldistribution,thestandard-deviation.(Thestandarddeviationmaynotbenegative.)

random-exponentialreportsanexponentiallydistributedrandomfloatingpointnumber.Itisequivalentto(- mean) * ln random-float 1.0.

random-gammareportsagamma-distributedrandomfloatingpointnumberascontrolledbythefloatingpointalphaandlambdaparameters.Bothinputsmustbegreaterthanzero.(Note:forresultswithagivenmeanandvariance,useinputsasfollows:alpha=mean*mean/variance;lambda=1/(variance/mean).)

random-normalreportsanormallydistributedrandomfloatingpointnumber.

random-poissonreportsaPoisson-distributedrandominteger.

show random-exponential 2;; prints an exponentially distributed random floating;; point number with a mean of 2show random-normal 10.1 5.2;; prints a normally distributed random floating point;; number with a mean of 10.1 and a standard deviation;; of 5.2show random-poisson 3.4;; prints a Poisson-distributed random integer with a;; mean of 3.4

random-pxcorrandom-pycor

random-pxcorrandom-pycor

Reportsarandomintegerrangingfrommin-pxcor(or-y)tomax-pxcor(or-y)inclusive.

ask turtles [ ;; move each turtle to the center of a random patch setxy random-pxcor random-pycor]

Seealsorandom-xcor,random-ycor.

random-seed

random-seednumber

Setstheseedofthepseudo-randomnumbergeneratortotheintegerpartofnumber.Theseedmustbeintherange-2147483648to2147483647;notethatthisissmallerthanthefullrangeofintegerssupportedbyNetLogo(-9007199254740992to9007199254740992).

SeetheRandomNumberssectionoftheProgrammingGuideformoredetails.

random-seed 47822show random 100=> 50show random 100=> 35random-seed 47822show random 100=> 50show random 100=> 35

random-xcorrandom-ycor

random-xcorrandom-ycor

Reportsarandomfloatingpointnumberfromtheallowablerangeofturtlecoordinatesalongthegivenaxis,xory.

Since6.0

Since1.1

Since1.3

Turtlecoordinatesrangefrommin-pxcor-0.5(inclusive)tomax-pxcor+0.5(exclusive)horizontally;vertically,substitute-yfor-x.

ask turtles [ ;; move each turtle to a random point setxy random-xcor random-ycor]

Seealsorandom-pxcor,random-pycor.

range

rangestop(rangestartstop)(rangestartstopstep)

Generatesalistofnumbers,startingatstart,endingbeforestop,countingbystep.startdefaultsto0andstepdefaultsto1.

show range 5=> [0 1 2 3 4]show (range 2 5)=> [2 3 4]show (range 2 5 0.5)=> [2 2.5 3 3.5 4 4.5]show (range 10 0 -1)=> [10 9 8 7 6 5 4 3 2 1]

Seealson-values

read-from-string

read-from-stringstring

InterpretsthegivenstringasifithadbeentypedintheCommandCenter,andreportstheresultingvalue.Theresultmaybeanumber,list,string,orbooleanvalue,orthespecialvalue"nobody".

Usefulinconjunctionwiththeuser-inputprimitiveforconvertingtheuser'sinputintousableform.

show read-from-string "3" + read-from-string "5"=> 8show length read-from-string "[1 2 3]"=> 3crt read-from-string user-input "Make how many turtles?";; the number of turtles input by the user;; are created

reduce

reducereporterlist

Reducesalistfromlefttorightusingthegivenreporter,resultinginasinglevalue.Thismeans,forexample,thatreduce [ [a b] -> a + b][1 2 3 4]isequivalentto(((1+2)+3)+4).Iflisthasasingleitem,thatitemisreported.Itisanerrortoreduceanemptylist.reportermaybeananonymousreporterorthenameofareporter.

Thefirstinputpassedtothereporteristheresultsofar,andthesecondinputisthenextiteminthelist.

Sinceitcanbedifficulttodevelopanintuitionaboutwhatreducedoes,herearesomesimpleexampleswhich,whilenotusefulinthemselves,maygiveyouabetterunderstandingofthisprimitive:

show reduce + [1 2 3]=> 6show reduce - [1 2 3]=> -4show reduce [ [result-so-far next-item] -> next-item - result-so-far ] [1 2 3]=> 2show reduce [ [result-so-far ignored-item] -> result-so-far ] [1 2 3]=> 1show reduce [ [ignored next-item] -> next-item ] [1 2 3]=> 3show reduce sentence [[1 2] [3 [4]] 5]=> [1 2 3 [4] 5]show reduce [ [result-so-far next-item] -> fput next-item result-so-far ] (fput [] [1 2 3 4 5])=> [5 4 3 2 1]

Herearesomemoreusefulexamples:

;; find the longest string in a listto-report longest-string [strings] report reduce [ [longest-so-far next-string] -> ifelse-value (length longest-so-far >= length next-string) [longest-so-far] [next-string] ] stringsend

show longest-string ["hi" "there" "!"]=> "there"

;; count the number of occurrences of an item in a listto-report occurrences [x the-list] report reduce [ [occurrence-count next-item] -> ifelse-value (next-item = x) [occurrence-count + 1] [occurrence-count] ] (fput 0 the-list)end

show occurrences 1 [1 2 1 3 1 2 3 1 1 4 5 1]

Since1.2.1

Since1.0

Since1.0

Since2.0

Since1.0

Since1.0

=> 6

;; evaluate the polynomial, with given coefficients, at xto-report evaluate-polynomial [coefficients x] report reduce [ [value coefficient] -> (x * value) + coefficient ] coefficientsend

;; evaluate 3x^2 + 2x + 1 at x = 4show evaluate-polynomial [3 2 1] 4=> 57

Seealsofilter,->(anonymousprocedure.

remainder

remaindernumber1number2

Reportstheremainderwhennumber1isdividedbynumber2.ThisisequivalenttothefollowingNetLogocode:

number1 - (int (number1 / number2)) * number2

show remainder 62 5=> 2show remainder -8 3=> -2

Seealsomod.modandremainderbehavethesameforpositivenumbers,butdifferentlyfornegativenumbers.

remove

removeitemlistremovestring1string2

Foralist,reportsacopyoflistwithallinstancesofitemremoved.

Forstrings,reportsacopyofstring2withalltheappearancesofstring1asasubstringremoved.

set mylist [2 7 4 7 "Bob"]set mylist remove 7 mylist;; mylist is now [2 4 "Bob"]show remove "to" "phototonic"=> "phonic"

remove-duplicates

remove-duplicateslist

Reportsacopyoflistwithallduplicateitemsremoved.Thefirstofeachitemremainsinplace.

set mylist [2 7 4 7 "Bob" 7]set mylist remove-duplicates mylist;; mylist is now [2 7 4 "Bob"]

remove-item

remove-itemindexlistremove-itemindexstring

Foralist,reportsacopyoflistwiththeitematthegivenindexremoved.

Forstrings,reportsacopyofstringwiththecharacteratthegivenindexremoved.

Notethattheindicesbeginfrom0,not1.(Thefirstitemisitem0,theseconditemisitem1,andsoon.)

set mylist [2 7 4 7 "Bob"]set mylist remove-item 2 mylist;; mylist is now [2 7 7 "Bob"]show remove-item 2 "string"=> "sting"

repeat

repeatnumber[commands]

Runscommandsnumbertimes.

pd repeat 36 [ fd 1 rt 10 ] ;; the turtle draws a circle

replace-item

Since1.0

Since3.0Since3.0

Since4.0

Since1.0

Since4.1

Since1.0

Since1.0

replace-itemindexlistvaluereplace-itemindexstring1string2

Onalist,replacesaniteminthatlist.indexistheindexoftheitemtobereplaced,startingwith0.(The6thiteminalistwouldhaveanindexof5.)Notethat"replace-item"isusedinconjunctionwith"set"tochangealist.

Likewiseforastring,butthegivencharacterofstring1removedandthecontentsofstring2splicedininstead.

show replace-item 2 [2 7 4 5] 15=> [2 7 15 5]show replace-item 1 "cat" "are"=> "caret"

report

reportvalue

Immediatelyexitsfromthecurrentto-reportprocedureandreportsvalueastheresultofthatprocedure.reportandto-reportarealwaysusedinconjunctionwitheachother.Seeto-reportforadiscussionofhowtousethem.

reset-perspectiverp

reset-perspective

Theobserverstopswatching,following,orridinganyturtles(orpatches).(Ifitwasn'twatching,following,orridinganybody,nothinghappens.)Inthe3Dview,theobserveralsoreturnstoitsdefaultposition(abovetheorigin,lookingstraightdown).

Seealsofollow,ride,watch.

reset-ticks

reset-ticks

Resetsthetickcountertozero,setsupallplots,thenupdatesallplots(sothattheinitialstateoftheworldisplotted).

Normallyreset-ticksgoesattheendofasetupprocedure.

Seealsoclear-ticks,tick,ticks,tick-advance,setup-plots,update-plots.

reset-timer

reset-timer

Resetsthetimertozeroseconds.Seealsotimer.

Notethatthetimerisdifferentfromthetickcounter.Thetimermeasureselapsedrealtimeinseconds;thetickcountermeasureselapsedmodeltimeinticks.

resize-world

resize-worldmin-pxcormax-pxcormin-pycormax-pycor

Changesthesizeofthepatchgrid.

Asasideeffect,allturtlesandlinksdie,andtheexistingpatchgridisdiscardedandnewpatchescreated.

Retainingreferencestooldpatchesorpatchsetsisinadvisableandmaysubsequentlycauseruntimeerrorsorotherunexpectedbehavior.

Seealsoset-patch-size.

reverse

reverselistreversestring

Reportsareversedcopyofthegivenlistorstring.

show mylist;; mylist is [2 7 4 "Bob"]set mylist reverse mylist;; mylist now is ["Bob" 4 7 2]show reverse "live"=> "evil"

rgb

rgbredgreenblue

Since3.0

Since3.0

Since1.0Since1.0

Since1.0

Since1.3Since1.3

ReportsaRGBlistwhengiventhreenumbersdescribinganRGBcolor.Thenumbersarerangecheckedtobebetween0and255.

Seealsohsb

ride

rideturtle

Settheperspectivetoturtle.

Everytimeturtlemovestheobserveralsomoves.Thus,inthe2DViewtheturtlewillstayatthecenteroftheview.Inthe3Dviewitisasiflookingthroughtheeyesoftheturtle.Iftheturtledies,theperspectiveresetstothedefault.

Theobservermayonlywatchorfollowasinglesubject.Callingridewillremovethehighlightcreatedbypriorcallstowatchandwatch-me,highlightingtheriddenturtleinstead.

Seealsoreset-perspective,watch,follow,subject.

ride-me

ride-me

Askstheobservertoridethisturtle.

Theobservermayonlywatchorfollowasinglesubject.Callingride-mewillremovethehighlightcreatedbypriorcallstowatchandwatch-me,highlightingthisturtleinstead.

Seealsoride.

rightrt

rightnumber

Theturtleturnsrightbynumberdegrees.(Ifnumberisnegative,itturnsleft.)

round

roundnumber

Reportstheintegernearesttonumber.

Ifthedecimalportionofnumberisexactly.5,thenumberisroundedinthepositivedirection.

Notethatroundinginthepositivedirectionisnotalwayshowroundingisdoneinothersoftwareprograms.(Inparticular,itdoesnotmatchthebehaviorofStarLogoT,whichalwaysroundednumbersendingin0.5tothenearesteveninteger.)TherationaleforthisbehavioristhatitmatcheshowturtlecoordinatesrelatetopatchcoordinatesinNetLogo.Forexample,ifaturtle'sxcoris-4.5,thenitisontheboundarybetweenapatchwhosepxcoris-4andapatchwhosepxcoris-5,buttheturtlemustbeconsideredtobeinonepatchortheother,sotheturtleisconsideredtobeinthepatchwhosepxcoris-4,becauseweroundtowardsthepositivenumbers.

show round 4.2=> 4show round 4.5=> 5show round -4.5=> -4

Seealsoprecision,ceiling,floor.

runrunresult

runcommand(runcommandinput1...)runstringrunresultreporter(runresultreporterinput1...)runresultstring

Therunformexpectsthenameofacommand,ananonymouscommand,orastringcontainingcommands.Thisagentthenrunsthem.

Therunresultformexpectsthenameofareporter,ananonymousreporter,orastringcontainingareporter.Thisagentrunsitandreportstheresult.

Notethatyoucan'tuseruntodefineorredefineprocedures.Ifyoucareaboutperformance,notethatthecodemustbecompiledfirstwhichtakestime.However,compiledbitsofcodearecachedbyNetLogoandthususingrunonthesamestringoverandoverismuchfasterthanrunningdifferentstrings.Thefirstrun,though,willbemanytimesslowerthanrunningthesamecodedirectly,orinananonymouscommand.

Since1.0

Since1.3

Since1.0Since1.0

Since1.0

Anonymousproceduresarerecommendedoverstringswheneverpossible.(Anexampleofwhenyoumustusestringsisifyouacceptpiecesofcodefromtheuserofyourmodel.)

Anonymousproceduresmayfreelyreadand/orsetlocalvariablesandprocedureinputs.Tryingtodothesamewithstringsmayormaynotworkandshouldnotbereliedon.

Whenusinganonymousprocedures,youcanprovidethemwithinputs,ifyousurroundtheentirecallwithparentheses.Forexample:

(run [ [turtle-count step-count] -> crt turtle-count [ fd step-count ] ] 10 5);; creates 10 turtles and move them forward 5 stepsshow (runresult [ [a b] -> a + b ] 10 5)=> 15;; adds 10 and 5

Seealsoforeach,->(anonymousprocedure).

S

scale-color

scale-colorcolornumberrange1range2

Reportsashadeofcolorproportionaltothevalueofnumber.

Ifrange1islessthanrange2,thenthelargerthenumber,thelightertheshadeofcolor.Butifrange2islessthanrange1,thecolorscalingisinverted.

Ifnumberislessthanrange1,thenthedarkestshadeofcolorischosen.

Ifnumberisgreaterthanrange2,thenthelightestshadeofcolorischosen.

Note:forcolorshadeisirrelevant,e.g.greenandgreen+2areequivalent,andthesamespectrumofcolorswillbeused.

ask turtles [ set color scale-color red age 0 50 ];; colors each turtle a shade of red proportional;; to its value for the age variable

self

self

Reportsthisturtle,patch,orlink.

"self"and"myself"areverydifferent."self"issimple;itmeans"me"."myself"means"theagentwhoaskedmetodowhatI'mdoingrightnow."

Notethatitisalwaysredundanttowrite[foo] of self.Thisisalwaysequivalenttosimplywritingfoo.

Seealsomyself.

;(semicolon)

;comments

Afterasemicolon,therestofthelineisignored.Thisisusefulforadding"comments"toyourcode--textthatexplainsthecodetohumanreaders.Extrasemicolonscanbeaddedforvisualeffect.

NetLogo'sEditmenuhasitemsthatletyoucommentoruncommentwholesectionsofcode.

sentencese

sentencevalue1value2(sentencevalue1...)

Makesalistoutofthevalues.Ifanyvalueisalist,itsitemsareincludedintheresultdirectly,ratherthanbeingincludedasasublist.Examplesmakethisclearer:

show sentence 1 2=> [1 2]show sentence [1 2] 3=> [1 2 3]show sentence 1 [2 3]=> [1 2 3]show sentence [1 2] [3 4]=> [1 2 3 4]show sentence [[1 2]] [[3 4]]=> [[1 2] [3 4]]show (sentence [1 2] 3 [4 5] (3 + 3) 7)=> [1 2 3 4 5 6 7]

set

foreach

arrow

Since2.0

Since1.0

Since1.0

Since1.0

Since1.0

setvariablevalue

Setsvariabletothegivenvalue.

Variablecanbeanyofthefollowing:

Aglobalvariabledeclaredusing"globals"Theglobalvariableassociatedwithaslider,switch,chooser,orinputbox.AvariablebelongingtothisagentIfthisagentisaturtle,avariablebelongingtothepatchundertheturtle.Alocalvariablecreatedbytheletcommand.Aninputtothecurrentprocedure.

set-current-directory

set-current-directorystring

Setsthecurrentdirectorythatisusedbytheprimitivesfile-delete,file-exists?,andfile-open.

Thecurrentdirectoryisnotusediftheabovecommandsaregivenanabsolutefilepath.Thisisdefaultedtotheuser'shomedirectoryfornewmodels,andischangedtothemodel'sdirectorywhenamodelisopened.

NotethatinWindowsfilepathsthebackslashneedstobeescapedwithinastringbyusinganotherbackslash"C:\\"

Thechangeistemporaryandisnotsavedwiththemodel.

set-current-directory "C:\\NetLogo";; Assume it is a Windows Machinefile-open "my-file.txt";; Opens file "C:\\NetLogo\\my-file.txt"

set-current-plot

set-current-plotplotname

Setsthecurrentplottotheplotwiththegivenname(astring).Subsequentplottingcommandswillaffectthecurrentplot.

set-current-plot-pen

set-current-plot-penpenname

Thecurrentplot'scurrentpenissettothepennamedpenname(astring).Ifnosuchpenexistsinthecurrentplot,aruntimeerroroccurs.

set-default-shape

set-default-shapeturtlesstringset-default-shapelinksstringset-default-shapebreedstring

Specifiesadefaultinitialshapeforallturtlesorlinks,orforaparticularbreedofturtlesorlinks.Whenaturtleorlinkiscreated,oritchangesbreeds,itshapeissettothegivenshape.

Thiscommanddoesn'taffectexistingagents,onlyagentsyoucreateafterwards.

Thegivenbreedmustbeeitherturtles,links,orthenameofabreed.Thegivenstringmustbethenameofacurrentlydefinedshape.

Innewmodels,thedefaultshapeforallturtlesis"default".

Notethatspecifyingadefaultshapedoesnotpreventyoufromchanginganagent'sshapelater.Agentsdon'thavetobestuckwiththeirbreed'sdefaultshape.

create-turtles 1 ;; new turtle's shape is "default"create-cats 1 ;; new turtle's shape is "default"

set-default-shape turtles "circle"create-turtles 1 ;; new turtle's shape is "circle"create-cats 1 ;; new turtle's shape is "circle"

set-default-shape cats "cat"set-default-shape dogs "dog"create-cats 1 ;; new turtle's shape is "cat"ask cats [ set breed dogs ] ;; all cats become dogs, and automatically ;; change their shape to "dog"

Seealsoshape.

set-histogram-num-bars

set-histogram-num-barsnumber

Setthecurrentplotpen'splotintervalsothat,giventhecurrentxrangefortheplot,therewouldbenumbernumberofbarsdrawnifthehistogramcommandiscalled.

Since4.1

Since6.0.2

Since1.0

Since1.0

Since1.0

Since5.0

Since1.0Since1.0

Seealsohistogram.

__set-line-thickness

__set-line-thicknessnumber

Specifiesthethicknessoflinesandoutlinedelementsintheturtle'sshape.

Thedefaultvalueis0.Thisalwaysproduceslinesonepixelthick.

Non-zerovaluesareinterpretedasthicknessinpatches.Athicknessof1,forexample,produceslineswhichappearonepatchthick.(It'scommontouseasmallervaluesuchas0.5or0.2.)

Linesarealwaysatleastonepixelthick.

Thiscommandisexperimentalandmaychangeinlaterreleases.

set-patch-size

set-patch-sizesize

Setsthesizeofthepatchesoftheviewinpixels.Thesizeistypicallyaninteger,butmayalsobeafloatingpointnumber.

Seealsopatch-size,resize-world.

set-plot-background-color

set-plot-background-colorcolor

Setsthebackgroundcolorofthecurrentplot.Thecolormaybespecifiedasanumberoralist.SeetheColorssectionoftheprogrammingguideformoredetails.Thischangeistemporaryandisnotsavedwiththemodel.Whentheplotiscleared,thebackgroundcolorwillreverttowhite.

Note:Plotbackgroundsdonotsupporttransparency.Ifalistisusedtosetthecolor,thealphacomponentwillbeignored.

set-plot-pen-color

set-plot-pen-colorcolor

Setsthecolorofthecurrentplotpentocolor.

set-plot-pen-interval

set-plot-pen-intervalnumber

Tellsthecurrentplotpentomoveadistanceofnumberinthexdirectionduringeachuseoftheplotcommand.(Theplotpenintervalalsoaffectsthebehaviorofthehistogramcommand.)

set-plot-pen-mode

set-plot-pen-modenumber

Setsthemodethecurrentplotpendrawsintonumber.Theallowedplotpenmodesare:

0(linemode)theplotpendrawsalineconnectingtwopointstogether.1(barmode):theplotpendrawsabarofwidthplot-pen-intervalwiththepointplottedastheupper(orlower,ifyouareplottinganegativenumber)leftcornerofthebar.2(pointmode):theplotpendrawsapointatthepointplotted.Pointsarenotconnected.

Thedefaultmodefornewpensis0(linemode).

setup-plots

setup-plots

Foreachplot,runsthatplot'ssetupcommands,includingthesetupcodeforanypensintheplot.

reset-tickshasthesameeffect,soinmodelsthatusethetickcounter,thisprimitiveisnotnormallyused.

SeethePlottingsectionoftheProgrammingGuideformoredetails.

Seealsoupdate-plots.

set-plot-x-rangeset-plot-y-range

set-plot-x-rangeminmax

Since1.0

Since1.0

Since2.1

Since1.0

set-plot-y-rangeminmax

Setstheminimumandmaximumvaluesofthexoryaxisofthecurrentplot.

Thechangeistemporaryandisnotsavedwiththemodel.Whentheplotiscleared,therangeswillreverttotheirdefaultvaluesassetintheplot'sEditdialog.

setxy

setxyxy

Theturtlesetsitsx-coordinatetoxanditsy-coordinatetoy.

Equivalenttoset xcor x set ycor y,exceptithappensinonetimestepinsteadoftwo.

Ifxoryisoutsidetheworld,NetLogowillthrowaruntimeerror,unlesswrappingisturnedonintherelevantdimensions.Forexample,withwrappingturnedoninbothdimensionsandthedefaultworldsizewheremin-pxcor = -16,max-pxcor = 16,min-pycor = -16andmax-pycor =16,askingaturtletosetxy 17 17willmoveittothecenterofpatch(-16,-16).

setxy 0 0;; turtle moves to the middle of the center patchsetxy random-xcor random-ycor;; turtle moves to a random pointsetxy random-pxcor random-pycor;; turtle moves to the center of a random patch

Seealsomove-to.

shade-of?

shade-of?color1color2

Reportstrueifbothcolorsareshadesofoneanother,falseotherwise.

show shade-of? blue red=> falseshow shade-of? blue (blue + 1)=> trueshow shade-of? gray white=> true

shape

shape

Thisisabuilt-inturtleandlinkvariable.Itholdsastringthatisthenameoftheturtleorlink'scurrentshape.Youcansetthisvariabletochangetheshape.Newturtlesandlinkshavetheshape"default"unlesstheadifferentshapehasbeenspecifiedusingset-default-shape.

Example:

ask turtles [ set shape "wolf" ];; assumes you have made a "wolf";; shape in NetLogo's Turtle Shapes Editorask links [ set shape "link 1" ];; assumes you have made a "link 1" shape in;; the Link Shapes Editor

Seealsoset-default-shape,shapes.

shapes

shapes

Reportsalistofstringscontainingalloftheturtleshapesinthemodel.

Newshapescanbecreated,orimportedfromtheshapeslibraryorfromothermodels,intheShapesEditor.

show shapes=> ["default" "airplane" "arrow" "box" "bug" ...ask turtles [ set shape one-of shapes ]

show

showvalue

PrintsvalueintheCommandCenter,precededbythisagent,andfollowedbyacarriagereturn.(Thisagentisincludedtohelpyoukeeptrackofwhatagentsareproducingwhichlinesofoutput.)Also,allstringshavetheirquotesincludedsimilartowrite.

Seealsoprint,type,andwrite.

Since1.0Since1.0

Since4.0

Since2.0

Since1.0

Since1.0

Seealsooutput-show.

show-turtlest

show-turtle

Theturtlebecomesvisibleagain.

Note:Thiscommandisequivalenttosettingtheturtlevariable"hidden?"tofalse.

Seealsohide-turtle.

show-link

show-link

Thelinkbecomesvisibleagain.

Note:Thiscommandisequivalenttosettingthelinkvariable"hidden?"tofalse.

Seealsohide-link.

shuffle

shufflelist

Reportsanewlistcontainingthesameitemsastheinputlist,butinrandomizedorder.

show shuffle [1 2 3 4 5]=> [5 2 4 1 3]show shuffle [1 2 3 4 5]=> [1 3 5 2 4]

sin

sinnumber

Reportsthesineofthegivenangle.Assumesangleisgivenindegrees.

show sin 270=> -1

size

size

Thisisabuilt-inturtlevariable.Itholdsanumberthatistheturtle'sapparentsize.Thedefaultsizeis1,whichmeansthattheturtleisthesamesizeasapatch.Youcansetthisvariabletochangeaturtle'ssize.

sort

sortlistsortagentset

Reportsasortedlistofnumbers,strings,oragents.

Iftheinputcontainsnonumbers,strings,oragents,theresultistheemptylist.

Iftheinputcontainsatleastonenumber,thenumbersinthelistaresortedinascendingorderandanewlistreported;non-numbersareignored.

Or,iftheinputcontainsatleastonestring,thestringsinthelistaresortedinascendingorderandanewlistreported;non-stringsareignored.

Or,iftheinputisanagentsetoralistcontainingatleastoneagent,asortedlistofagents(neveranagentset)isreported;non-agentsareignored.Agentsaresortedinthesameorderthe<operatoruses.(Patchesaresortedwiththetopleft-mostpatchfirstandthebottomright-mostpatchlast,turtlesaresortedbywhonumber).

show sort [3 1 4 2]=> [1 2 3 4]show sort [2 1 "a"]=> [1 2]show sort (list "a" "c" "b" (patch 0 0))=> ["a" "b" "c"]show sort (list (patch 0 0) (patch 0 1) (patch 1 0))=> [(patch 0 1) (patch 0 0) (patch 1 0)]

;; label patches with numbers in left-to-right, top-to-bottom order

Since1.3

Since5.0

Since1.0

Since1.0

let n 0foreach sort patches [ the-patch -> ask the-patch [ set plabel n set n n + 1 ]]

;; some additional examples to clarify behavior in strange casesshow sort (list patch 0 0 patch 0 1 patch 1 0 turtle 0 turtle 1) ; turtles are always sorted lower than patches=> [(turtle 0) (turtle 1) (patch 0 1) (patch 0 0) (patch 1 0)]show sort (list nobody false true) ; booleans and nobody cannot be sorted=> []show sort (list [1 2 3] turtles) ; lists and agentsets are not included if they are inside a list passed to sort=> []

Seealsosort-by,sort-on.

sort-by

sort-byreporterlistsort-byreporteragentset

Iftheinputisalist,reportsanewlistcontainingthesameitemsastheinputlist,inasortedorderdefinedbythebooleanreporter.reportermaybeananonymousreporterorthenameofareporter.

Thetwoinputstoreporterarethevaluesbeingcompared.Thereportershouldreporttrueifthefirstargumentcomesstrictlybeforethesecondinthedesiredsortorder,andfalseotherwise.

Iftheinputisanagentsetoralistofagents,reportsalist(neveranagentset)ofagents.

Iftheinputisalist,thesortisstable,thatis,theorderofitemsconsideredequalbythereporterisnotdisturbed.Iftheinputisanagentset,tiesarebrokenrandomly.

show sort-by < [3 1 4 2]=> [1 2 3 4]show sort-by > [3 1 4 2]=> [4 3 2 1]show sort-by [ [string1 string2] -> length string1 < length string2 ] ["Grumpy" "Doc" "Happy"]=> ["Doc" "Happy" "Grumpy"]

Seealsosort,sort-on,->(anonymousprocedure).

sort-on

sort-on[reporter]agentset

Reportsalistofagents,sortedaccordingtoeachagent'svalueforreporter.Tiesarebrokenrandomly.

Thevaluesmustbeallnumbers,allstrings,orallagentsofthesametype.

crt 3show sort-on [who] turtles=> [(turtle 0) (turtle 1) (turtle 2)]show sort-on [(- who)] turtles=> [(turtle 2) (turtle 1) (turtle 0)]foreach sort-on [size] turtles [ the-turtle -> ask the-turtle [ do-something ] ];; turtles run "do-something" one at a time, in;; ascending order by size

Seealsosort,sort-by.

sprout

sproutnumber[commands]sprout-<breeds>number[commands]

Createsnumbernewturtlesonthecurrentpatch.Thenewturtleshaverandomintegerheadingsandthecolorisrandomlyselectedfromthe14primarycolors.Theturtlesimmediatelyruncommands.Thisisusefulforgivingthenewturtlesdifferentcolors,headings,orwhatever.(Thenewturtlesarecreatedallatoncethenrunoneatatime,inrandomorder.)

Ifthesprout-<breeds>formisused,thenewturtlesarecreatedasmembersofthegivenbreed.

sprout 5sprout-wolves 10sprout 1 [ set color red ]sprout-sheep 1 [ set color black ]

Seealsocreate-turtles,hatch.

sqrt

sqrtnumber

Reportsthesquarerootofnumber.

Since1.0

Since3.1

Since1.0

Since1.0

Since5.2

Since5.2

stamp

stamp

Thisturtleorlinkleavesanimageofitsshapeinthedrawingatitscurrentlocation.

Note:Theshapesmadebystampmaynotbepixel-for-pixelidenticalfromcomputertocomputer.

stamp-erase

stamp-erase

Thisturtleorlinkremovesanypixelsbelowitinthedrawinginsidetheboundsofitsshape.

Note:Theshapesmadebystamp-erasemaynotbepixel-for-pixelidenticalfromcomputertocomputer.

standard-deviation

standard-deviationlist

Reportsthesamplestandarddeviationofalistofnumbers.Ignoresothertypesofitems.

(Notethatthisestimatesthestandarddeviationforasample,ratherthanforawholepopulation,usingBessel'scorrection.)

show standard-deviation [1 2 3 4 5 6]=> 1.8708286933869707show standard-deviation [energy] of turtles;; prints the standard deviation of the variable "energy";; from all the turtles

startup

startup

User-definedprocedurewhich,ifitexists,willbecalledwhenamodelisfirstloadedintheNetLogoapplication.

to startup setupend

startupdoesnotrunwhenamodelisrunheadlessfromthecommandline,orbyparallelBehaviorSpace.

stop

stop

Thisagentexitsimmediatelyfromtheenclosingprocedure,ask,orask-likeconstruct(e.g.crt,hatch,sprout).Onlytheenclosingprocedureorconstructstops,notallexecutionfortheagent.

if not any? turtles [ stop ];; exits if there are no more turtles

Note:stopcanalsobeusedtostopaforeverbutton.SeeButtonsintheProgrammingGuidefordetails.

stopcanalsobeusedtostopaBehaviorSpacemodelrun.Ifthegocommandsdirectlycallaprocedure,thenwhenthatprocedurecallsstop,therunends.

stop-inspecting

stop-inspectingagent

Closestheagentmonitorforthegivenagent(turtleorpatch).Inthecasethatnoagentmonitorisopen,stop-inspectingdoesnothing.

stop-inspecting patch 2 4;; the agent monitor for that patch closesask sheep [ stop-inspecting self ];; close all agent monitors for sheep

Seeinspectandstop-inspecting-dead-agents.

stop-inspecting-dead-agents

stop-inspecting-dead-agents

Closesallagentmonitorsfordeadagents.Seeinspectandstop-inspecting.

Since3.0

Since2.1Since1.0

Since2.1

Since1.0

Since1.0

Since4.0

subject

subject

Reportstheturtle(orpatch)thattheobserveriscurrentlywatching,following,orriding.Reportsnobodyifthereisnosuchturtle(orpatch).

Seealsowatch,follow,ride.

sublistsubstring

sublistlistposition1position2substringstringposition1position2

Reportsjustasectionofthegivenlistorstring,rangingbetweenthefirstposition(inclusive)andthesecondposition(exclusive).

Note:Thepositionsarenumberedbeginningwith0,notwith1.

show sublist [99 88 77 66] 1 3=> [88 77]show substring "apartment" 1 5=> "part"

subtract-headings

subtract-headingsheading1heading2

Computesthedifferencebetweenthegivenheadings,thatis,thenumberofdegreesinthesmallestanglebywhichheading2couldberotatedtoproduceheading1.Apositiveanswermeansaclockwiserotation,anegativeanswercounterclockwise.Theresultisalwaysintherange-180to180,butisneverexactly-180.

Notethatsimplysubtractingthetwoheadingsusingthe-(minus)operatorwouldn'twork.Justsubtractingcorrespondstoalwaysrotatingclockwisefromheading2toheading1;butsometimesthecounterclockwiserotationisshorter.Forexample,thedifferencebetween5degreesand355degreesis10degrees,not-350degrees.

show subtract-headings 80 60=> 20show subtract-headings 60 80=> -20show subtract-headings 5 355=> 10show subtract-headings 355 5=> -10show subtract-headings 180 0=> 180show subtract-headings 0 180=> 180

sum

sumlist

Reportsthesumoftheitemsinthelist.

show sum [energy] of turtles;; prints the total of the variable "energy";; from all the turtles

T

tan

tannumber

Reportsthetangentofthegivenangle.Assumestheangleisgivenindegrees.

thickness

thickness

Thisisabuilt-inlinkvariable.Itholdsanumberthatisthelink'sapparentsizeasafractionofthepatchsize.Thedefaultthicknessis0,whichmeansthatregardlessofpatch-sizethelinkswillalwaysappear1pixelwide.Youcansetthisvariabletochangealink'sthickness.

tick

tick

Advancesthetickcounterbyoneandupdatesallplots.

Since4.0

Since4.0

Since4.0

Since1.0

Ifthetickcounterhasnotbeenstartedyetwithreset-ticks,anerrorresults.

Normallytickgoesattheendofagoprocedure.

Seealsoticks,tick-advance,reset-ticks,clear-ticks,update-plots.

tick-advance

tick-advancenumber

Advancesthetickcounterbynumber.Theinputmaybeanintegerorafloatingpointnumber.(Somemodelsdivideticksmorefinelythanbyones.)Theinputmaynotbenegative.

Whenusingtick-basedviewupdates,theviewisnormallyupdatedevery1.0ticks,sousingtick-advancewithanumberlessthen1.0maynotalwaystriggeranupdate.Ifyouwanttomakesurethattheviewisupdated,youcanusethedisplaycommand.


Doesnotupdateplots.

Seealsotick,ticks,reset-ticks,clear-ticks.

ticks

ticks

Reportsthecurrentvalueofthetickcounter.Theresultisalwaysanumberandnevernegative.


Mostmodelsusethetickcommandtoadvancethetickcounter,inwhichcasetickswillalwaysreportaninteger.Ifthetick-advancecommandisused,thenticksmayreportafloatingpointnumber.

Seealsotick,tick-advance,reset-ticks,clear-ticks.

tie

tie

Tiesend1andend2ofthelinktogether.Ifthelinkisadirectedlinkend1istherootturtleandend2istheleafturtle.Themovementoftherootturtleaffectsthelocationandheadingoftheleafturtle.Ifthelinkisundirectedthetieisreciprocalsobothturtlescanbeconsideredrootturtlesandleafturtles.Movementorchangeinheadingofeitherturtleaffectsthelocationandheadingoftheotherturtle.

Whentherootturtlemoves,theleafturtlesmovesthesamedistance,inthesamedirection.Theheadingoftheleafturtleisnotaffected.Thisworkswithforward,jump,andsettingthexcororycoroftherootturtle.

Whentherootturtleturnsrightorleft,theleafturtleisrotatedaroundtherootturtlethesameamount.Theheadingoftheleafturtleisalsochangedbythesameamount.

Ifthelinkdies,thetierelationisremoved.

crt 2 [ fd 3 ] ;; creates a link and ties turtle 1 to turtle 0 ask turtle 0 [ create-link-to turtle 1 [ tie ] ]

Seealsountie

tie-mode

tie-mode

Thisisabuilt-inlinkvariable.Itholdsastringthatisthenameofthetiemodethelinkiscurrentlyin.Usingthetieanduntiecommandschangesthemodeofthelink.Youcanalsosettie-modeto"free"tocreateanon-rigidjointbetweentwoturtles(seetheTiesectionoftheProgrammingGuidefordetails).Bydefaultlinksarenottied.

Seealso:tie,untie

timer

timer

Reportshowmanysecondshavepassedsincethecommandreset-timerwaslastrun(orsinceNetLogostarted).Thepotentialresolutionoftheclockismilliseconds.(Whetheryougetresolutionthathighinpracticemayvaryfromsystemtosystem,dependingonthecapabilitiesoftheunderlyingJavaVirtualMachine.)

Seealsoreset-timer.

Notethatthetimerisdifferentfromthetickcounter.Thetimermeasureselapsedrealtimeinseconds;thetickcountermeasureselapsed

Since1.0

Since1.0

Since1.0

modeltimeinticks.

to

toprocedure-nametoprocedure-name[input1...]

Usedtobeginacommandprocedure.

to setup clear-all crt 500end

to circle [radius] crt 100 [ fd radius ]end

to-report

to-reportprocedure-nameto-reportprocedure-name[input1...]

Usedtobeginareporterprocedure.

Thebodyoftheprocedureshouldusereporttoreportavaluefortheprocedure.Seereport.

to-report average [a b] report (a + b) / 2end

to-report absolute-value [number] ifelse number >= 0 [ report number ] [ report (- number) ]end

to-report first-turtle? report who = 0 ;; reports true or falseend

towards

towardsagent

Reportstheheadingfromthisagenttothegivenagent.

Ifwrappingisallowedbythetopologyandthewrappeddistance(aroundtheedgesoftheworld)isshorter,towardswillusethewrappedpath.

Note:askingfortheheadingfromanagenttoitself,oranagentonthesamelocation,willcausearuntimeerror.

set heading towards turtle 1;; same as "face turtle 1"

Seealsoface.

towardsxy

towardsxyxy

Reportstheheadingfromtheturtleorpatchtowardsthepoint(x,y).

Ifwrappingisallowedbythetopologyandthewrappeddistance(aroundtheedgesoftheworld)isshorter,towardsxywillusethewrappedpath.

Note:askingfortheheadingtothepointtheagentisalreadystandingonwillcausearuntimeerror.

Seealsofacexy.

turtle

turtlenumber<breed>number

Reportstheturtlewiththegivenwhonumber,ornobodyifthereisnosuchturtle.Forbreededturtlesyoumayalsousethesinglebreedformtorefertothem.

ask turtle 5 [ set color red ];; turtle with who number 5 turns red

Since4.0

Since1.0

Since1.0

Since1.0

Since2.0

turtle-set

turtle-setvalue1(turtle-setvalue1value2...)

Reportsanagentsetcontainingalloftheturtlesanywhereinanyoftheinputs.Theinputsmaybeindividualturtles,turtleagentsets,nobody,orlists(ornestedlists)containinganyoftheabove.

turtle-set self(turtle-set self turtles-on neighbors)(turtle-set turtle 0 turtle 2 turtle 9)(turtle-set frogs mice)

Seealsopatch-set,link-set.

turtles

turtles

Reportstheagentsetconsistingofallturtles.

show count turtles;; prints the number of turtles

turtles-at

turtles-atdxdy<breeds>-atdxdy

Reportsanagentsetcontainingtheturtlesonthepatch(dx,dy)fromthecaller.(Theresultmayincludethecalleritselfifthecallerisaturtle.)

create-turtles 5 [ setxy 2 3 ]show count [turtles-at 1 1] of patch 1 2=> 5

Ifthenameofabreedissubstitutedfor"turtles",thenonlyturtlesofthatbreedareincluded.

turtles-here

turtles-here<breeds>-here

Reportsanagentsetcontainingalltheturtlesonthecaller'spatch(includingthecalleritselfifit'saturtle).

crt 10ask turtle 0 [ show count turtles-here ]=> 10


breed [cats cat]breed [dogs dog]create-cats 5create-dogs 1ask dogs [ show count cats-here ]=> 5

turtles-on

turtles-onagentturtles-onagentset<breeds>-onagent<breeds>-onagentset

Reportsanagentsetcontainingalltheturtlesthatareonthegivenpatchorpatches,orstandingonthesamepatchasthegiventurtleorturtles.

ask turtles [ if not any? turtles-on patch-ahead 1 [ fd 1 ]]ask turtles [ if not any? turtles-on neighbors [ die-of-loneliness ]]

Since1.0

Since4.0

Since5.0

turtles-own

turtles-own[var1...]<breeds>-own[var1...]

Theturtles-ownkeyword,liketheglobals,breed,<breeds>-own,andpatches-ownkeywords,canonlybeusedatthebeginningofaprogram,beforeanyfunctiondefinitions.Itdefinesthevariablesbelongingtoeachturtle.

Ifyouspecifyabreedinsteadof"turtles",onlyturtlesofthatbreedhavethelistedvariables.(Morethanoneturtlebreedmaylistthesamevariable.)

breed [cats cat ]breed [dogs dog]breed [hamsters hamster]turtles-own [eyes legs] ;; applies to all breedscats-own [fur kittens]hamsters-own [fur cage]dogs-own [hair puppies]

Seealsoglobals,patches-own,breed,<breeds>-own.

type

typevalue

PrintsvalueintheCommandCenter,notfollowedbyacarriagereturn(unlikeprintandshow).Thelackofacarriagereturnallowsyoutoprintseveralvaluesonthesameline.

Thisagentisnotprintedbeforethevalue.unlikeshow.

type 3 type " " print 4=> 3 4

Seealsoprint,show,andwrite.

Seealsooutput-type.

U

undirected-link-breed

undirected-link-breed[<link-breeds><link-breed>]

Thiskeyword,liketheglobalsandbreedskeywords,canonlybeusedatthebeginningoftheCodetab,beforeanyproceduredefinitions.Itdefinesanundirectedlinkbreed.Linksofaparticularbreedarealwayseitheralldirectedorallundirected.Thefirstinputdefinesthenameoftheagentsetassociatedwiththelinkbreed.Thesecondinputdefinesthenameofasinglememberofthebreed.

Anylinkofthegivenlinkbreed:

ispartoftheagentsetnamedbythelinkbreednamehasitsbuilt-invariablebreedsettothatagentsetisdirectedorundirectedasdeclaredbythekeyword

Mostoften,theagentsetisusedinconjunctionwithasktogivecommandstoonlythelinksofaparticularbreed.

undirected-link-breed [streets street]undirected-link-breed [highways highway]to setup clear-all crt 2 ask turtle 0 [ create-street-with turtle 1 ] ask turtle 0 [ create-highway-with turtle 1 ]end

ask turtle 0 [ show sort my-links ];; prints [(street 0 1) (highway 0 1)]

Seealsobreed,directed-link-breed

untie

untie

Untiesend2fromend1(setstie-modeto"none")iftheywerepreviouslytiedtogether.Ifthelinkisanundirectedlink,thenitwilluntieend1fromend2aswell.Itdoesnotremovethelinkbetweenthetwoturtles.

Seealsotie

SeetheTiesectionoftheProgrammingGuideformoredetails.

update-plots

Since1.0Since1.0

Since3.1

Since3.1

Since3.1

Since1.1

update-plots

Foreachplot,runsthatplot'supdatecommands,includingtheupdatecodeforanypensintheplot.

tickhasthesameeffect,soinmodelsthatusethetickcounter,thisprimitiveisnotnormallyused.Modelsthatusefractionalticksmayneedupdate-plots,sincetick-advancedoesnotupdatetheplots.

SeethePlottingsectionoftheProgrammingGuideformoredetails.

Seealsosetup-plots.

uphilluphill4

uphillpatch-variableuphill4patch-variable

Movestheturtletotheneighboringpatchwiththehighestvalueforpatch-variable.Ifnoneighboringpatchhasahighervaluethanthecurrentpatch,theturtlestaysput.Iftherearemultiplepatcheswiththesamehighestvalue,theturtlepicksonerandomly.Non-numericvaluesareignored.

uphillconsiderstheeightneighboringpatches;uphill4onlyconsidersthefourneighbors.

Equivalenttothefollowingcode(assumesvariablevaluesarenumeric):

move-to patch-here ;; go to patch centerlet p max-one-of neighbors [patch-variable] ;; or neighbors4if [patch-variable] of p > patch-variable [ face p move-to p]

Notethattheturtlealwaysendsuponapatchcenterandhasaheadingthatisamultipleof45(uphill)or90(uphill4).

Seealsodownhill,downhill4.

user-directory

user-directory

Opensadialogthatallowstheusertochooseanexistingdirectoryonthesystem.

Itreportsastringwiththeabsolutepathorfalseiftheusercancels.

set-current-directory user-directory;; Assumes the user will choose a directory

user-file

user-file

Opensadialogthatallowstheusertochooseanexistingfileonthesystem.

Itreportsastringwiththeabsolutefilepathorfalseiftheusercancels.

file-open user-file;; Assumes the user will choose a file

user-new-file

user-new-file

Opensadialogthatallowstheusertochoosealocationandnameofanewfiletobecreated.Itreportsastringwiththeabsolutefilepathorfalseiftheusercancels.

file-open user-new-file;; Assumes the user will choose a file

Notethatthisreporterdoesn'tactuallycreatethefile;normallyyouwouldcreatethefileusingfile-open,asintheexample.

Iftheuserchoosesanexistingfile,theywillbeaskediftheywishtoreplaceitornot,butthereporteritselfdoesn'tcausethefiletobereplaced.Todothatyouwouldusefile-delete.

user-input

user-inputvalue

Reportsthestringthatausertypesintoanentryfieldinadialogwithtitlevalue.

Since1.1

Since3.1

Since2.0

Since1.0

Since1.0

valuemaybeofanytype,butistypicallyastring.

show user-input "What is your name?"

SeetheUserInteractionPrimitivessectionoftheProgrammingGuideforadditionaldetails.

user-message

user-messagevalue

Opensadialogwithvaluedisplayedasthemessagetotheuser.


user-message (word "There are " count turtles " turtles.")

Notethatifauserclosestheuser-messagedialogwiththe"X"inthecorner,thebehaviorwillbethesameasiftheyhadclicked"OK".


user-one-of

user-one-ofvaluelist-of-choices

Opensadialogwithvaluedisplayedasthemessageandlist-of-choicesdisplayedasapopupmenufortheusertoselectfrom.

Reportstheiteminlist-of-choicesselectedbytheuser.


if "yes" = user-one-of "Set up the model?" ["yes" "no"] [ setup ]


user-yes-or-no?

user-yes-or-no?value

Reportstrueorfalsebasedontheuser'sresponsetovalue.


if user-yes-or-no? "Set up the model?" [ setup ]


V

variance

variancelist

Reportsthesamplevarianceofalistofnumbers.Ignoresothertypesofitems.

(Notethatthiscomputesanunbiasedestimateofthevarianceforasample,ratherthanforawholepopulation,usingBessel'scorrection.)

Thesamplevarianceisthesumofthesquaresofthedeviationsofthenumbersfromtheirmean,dividedbyonelessthanthenumberofnumbersinthelist.

show variance [2 7 4 3 5]=> 3.7

W

wait

waitnumber

Waitthegivennumberofseconds.(Thisneedn'tbeaninteger;youcanspecifyfractionsofseconds.)Notethatyoucan'texpectcompleteprecision;theagentwillneverwaitlessthanthegivenamount,butmightwaitslightlymore.

repeat 10 [ fd 1 wait 0.5 ]

Whiletheagentiswaiting,nootheragentscandoanything.Everythingstopsuntiltheagentisdone.

Since3.0

Since3.0

Since1.0

Since1.0

Seealsoevery.

watch

watchagent

Putsaspotlightonagent.Inthe3Dviewtheobserverwillalsoturntofacethesubject.

Theobservermayonlywatchorfollowasinglesubject.Callingwatchwillundoperspectivechangescausedbypriorcallstofollow,follow-me,ride,andride-me.

Seealsofollow,subject,reset-perspective,ride,ride-me,watch-me.

watch-me

watch-me

Askstheobservertowatchthisagent.

Theobservermayonlywatchorfollowasinglesubject.Callingwatchwillundoperspectivechangescausedbypriorcallstofollow,follow-me,ride,andride-me.

Seealsofollow,subject,reset-perspective,ride,ride-me,watch.

while

while[reporter][commands]

Ifreporterreportsfalse,exittheloop.Otherwiseruncommandsandrepeat.

Thereportermayhavedifferentvaluesfordifferentagents,sosomeagentsmayruncommandsadifferentnumberoftimesthanotheragents.

while [any? other turtles-here] [ fd 1 ];; turtle moves until it finds a patch that has;; no other turtles on it

who

who

Thisisabuilt-inturtlevariable.Itholdstheturtle's"whonumber"orIDnumber,anintegergreaterthanorequaltozero.Youcannotsetthisvariable;aturtle'swhonumberneverchanges.

Whonumbersstartat0.Adeadturtle'snumberwillnotbereassignedtoanewturtleuntilyouusetheclear-turtlesorclear-allcommands,atwhichtimewhonumberingstartsoveragainat0.

Example:

show [who] of turtles with [color = red];; prints a list of the who numbers of all red turtles;; in the Command Center, in random ordercrt 100 [ ifelse who < 50 [ set color red ] [ set color blue ] ];; turtles 0 through 49 are red, turtles 50;; through 99 are blue

Youcanusetheturtlereportertoretrieveaturtlewithagivenwhonumber.Seealsoturtle.

Notethatwhonumbersaren'tbreed-specific.Notwoturtlescanhavethesamewhonumber,eveniftheyaredifferentbreeds:

clear-turtlescreate-frogs 1create-mice 1ask turtles [ print who ];; prints (in some random order):;; (frog 0): 0;; (mouse 1): 1

Eventhoughweonlyhaveonemouse,itismouse 1notmouse 0,becausethewhonumber0wasalreadytakenbythefrog.

with

agentsetwith[reporter]

Takestwoinputs:ontheleft,anagentset(usually"turtles"or"patches").Ontheright,abooleanreporter.Reportsanewagentsetcontainingonlythoseagentsthatreportedtrue--inotherwords,theagentssatisfyingthegivencondition.

Since4.0

Since2.1

Since2.1

Since4.0

Since1.1

show count patches with [pcolor = red];; prints the number of red patches

<breed>-withlink-with

<breed>-withturtlelink-withturtle

Reportsalinkbetweenturtleandthecaller(directedorundirected,incomingoroutgoing).Ifnolinkexiststhenitreportsnobody.Ifmorethanonesuchlinkexists,reportsarandomone.

crt 2ask turtle 0 [ create-link-with turtle 1 show link-with turtle 1 ;; prints link 0 1]

Seealso:in-link-from,out-link-to

with-max

agentsetwith-max[reporter]

Takestwoinputs:ontheleft,anagentset(usually"turtles"or"patches").Ontheright,areporter.Reportsanewagentsetcontainingallagentsreportingthemaximumvalueofthegivenreporter.

show count patches with-max [pxcor];; prints the number of patches on the right edge

Seealsomax-one-of,max-n-of.

with-min

agentsetwith-min[reporter]

Takestwoinputs:ontheleft,anagentset(usually"turtles"or"patches").Ontheright,areporter.Reportsanewagentsetcontainingonlythoseagentsthathavetheminimumvalueofthegivenreporter.

show count patches with-min [pycor];; prints the number of patches on the bottom edge

Seealsomin-one-of,min-n-of.

with-local-randomness

with-local-randomness[commands]

Thecommandsarerunwithoutaffectingsubsequentrandomevents.Thisisusefulforperformingextraoperations(suchasoutput)withoutchangingtheoutcomeofamodel.

Example:

;; Run #1:random-seed 50 setup repeat 10 [ go ];; Run #2:random-seed 50 setupwith-local-randomness [ watch one-of turtles ]repeat 10 [ go ]

Sinceone-ofisusedinsidewith-local-randomness,bothrunswillbeidentical.

Specificallyhowitworksis,thestateoftherandomnumbergeneratorisrememberedbeforethecommandsrun,thenrestoredafterwards.(Ifyouwanttorunthecommandswithafreshrandomstateinsteadofthesamerandomstatethatwillberestoredlater,youcanbeginthecommandswithrandom-seed new-seed.)

Thefollowingexampledemonstratesthattherandomnumbergeneratorstateisthesamebothbeforethecommandsrunandafterwards.

random-seed 10with-local-randomness [ print n-values 10 [random 10] ];; prints [8 9 8 4 2 4 5 4 7 9]print n-values 10 [random 10];; prints [8 9 8 4 2 4 5 4 7 9]

without-interruption

without-interruption[commands]

Thisprimitiveexistsonlyforbackwardscompatibility.Wedon'trecommendusingitinnewmodels.

Since1.0

Since3.1Since3.1

Since1.0

Since2.0

Theagentrunsallthecommandsintheblockwithoutallowingotheragentsusingask-concurrentto"interrupt".Thatis,otheragentsareput"onhold"anddonotrunanycommandsuntilthecommandsintheblockarefinished.

Note:Thiscommandisonlyusefulinconjunctionwithask-concurrent.

Seealsoask-concurrent.

word

wordvalue1value2(wordvalue1...)

Concatenatestheinputstogetherandreportstheresultasastring.

show word "tur" "tle"=> "turtle"word "a" 6=> "a6"set directory "c:\\foo\\fish\\"show word directory "bar.txt"=> "c:\foo\fish\bar.txt"show word [1 54 8] "fishy"=> "[1 54 8]fishy"show (word 3)=> "3"show (word "a" "b" "c" 1 23)=> "abc123"

world-widthworld-height

world-widthworld-height

ThesereportersgivethetotalwidthandheightoftheNetLogoworld.

Thewidthequalsmax-pxcor-min-pxcor+1andtheheightequalsmax-pycor-min-pycor+1.

Seealsomax-pxcor,max-pycor,min-pxcor,andmin-pycor

wrap-color

wrap-colornumber

wrap-colorcheckswhethernumberisintheNetLogocolorrangeof0to140(notincluding140itself).Ifitisnot,wrap-color"wraps"thenumericinputtothe0to140range.

Thewrappingisdonebyrepeatedlyaddingorsubtracting140fromthegivennumberuntilitisinthe0to140range.(Thisisthesamewrappingthatisdoneautomaticallyifyouassignanout-of-rangenumbertothecolorturtlevariableorpcolorpatchvariable.)

show wrap-color 150=> 10show wrap-color -10=> 130

write

writevalue

Thiscommandwilloutputvalue,whichcanbeanumber,string,list,boolean,ornobodytotheCommandCenter,notfollowedbyacarriagereturn(unlikeprintandshow).

Thisagentisnotprintedbeforethevalue,unlikeshow.Itsoutputalsoincludesquotesaroundstringsandisprependedwithaspace.

write "hello world"=> "hello world"

Seealsoprint,show,andtype.

Seealsooutput-write.

X

xcor

xcor

Thisisabuilt-inturtlevariable.Itholdsthecurrentxcoordinateoftheturtle.Youcansetthisvariabletochangetheturtle'slocation.

Thisvariableisalwaysgreaterthanorequalto(min-pxcor-0.5)andstrictlylessthan(max-pxcor+0.5).

Seealsosetxy,ycor,pxcor,pycor,

Since1.0

Since6.0

xor

boolean1xorboolean2

Reportstrueifeitherboolean1orboolean2istrue,butnotwhenbotharetrue.

if (pxcor > 0) xor (pycor > 0) [ set pcolor blue ];; upper-left and lower-right quadrants turn blue

Y

ycor

ycor

Thisisabuilt-inturtlevariable.Itholdsthecurrentycoordinateoftheturtle.Youcansetthisvariabletochangetheturtle'slocation.

Thisvariableisalwaysgreaterthanorequalto(min-pycor-0.5)andstrictlylessthan(max-pycor+0.5).

Seealsosetxy,xcor,pxcor,pycor,

->

->

[[args]->commands][[args]->reporter]

Createsandreportsananonymousprocedure-acommandorreporter-dependingontheinput.Withincommandsorreporterthelistedargsmaybeusedjustasyouwoulduseletorprocedurevariables.Thevariablenamesinargshavethesamerestrictionsasvariablenamesofcommandsandreporters.Inaddition,theymustnotmatchthenameofanyletorprocedurevariableintheirprocedure.

Anonymousproceduresarecommonlyusedwiththeprimitivesforeach,map,reduce,filter,sort-by,andn-values.Seethoseentriesforexampleusage.

SeetheAnonymousProceduressectionoftheProgrammingGuidefordetails.

NetLogo 6.0 User Manual

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