R Intro Workshop
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Transcript of R Intro Workshop
Intro Workshop
Saad Chahine, PhD. May 26, 2014
What is R?“R is a language and environment for statistical computing and graphics… similar to the S language and environment which was developed at Bell Laboratories… by John Chambers and colleagues…”
“R is available as Free Software under the terms of the Free Software Foundation's GNU General Public Licenses in source code form. It compiles and runs on a wide variety of UNIX platforms and similar systems (including FreeBSD and Linux), Windows and MacOS.”
http://www.r-project.org/
Getting Started
• Download and launch R
• Type help() press enter
Calculator
‘>’ is the prompt line Try: 3+5 Try: 3-5Try: 3/5Try: 3*5Try: sqrt(5)Try: sum (1,3,5)
Logic ‘>’ is the prompt line Try: 3<5 Try: 3>5Try: 3+5==8Try: 3+5==9
Variables‘<-’ assigns a value Try: x<-24 Try: xTry: x/2Try: xTry: x<-“hello world”Try: xTry: x<-TTry: x
Menu Bar
• Saving your documents • Working directories getwd()• Saving workspace
Help Example Try: help(ave)Try: help(mean)Try: help(mode)Try: help(median)Try: help(sd)Try: help(t.test)Try: help(anova)
Try: example(ave)Try: example(mean)Try: example(mode)Try: example(median)Try: example(sd)Try: example(t.test)Try: example(anova)
Vectors Try: c(3,5,7) Try: c(‘s’,’a’,’a’,’d’)Try: 3:7Try: seq(3,7)Try: seq(3,7,0.25) Try: 7:3Try: name <-c(‘s’,’a’,’a’,’d’)’Try: name [3]Try: name [3] <- ‘d’Try: name [4] <- ‘e’Try: name
Vectors Names
Try: ranks <- 1:3Try: names (ranks) <- c(“1st”,”2nd”,”3rd”, )Try: ranks Try: ranks [first]Try: ranks [3] <-4Try: scoRes <- c(450,578,502)Try: barplot(scoRes)Try: names(scoRes) <- c(“Bob”, “Marry”, “Jane”)Try: barplot (1:200)
Matrices
Try: matrix(0,6,7)Try: a<-1:42Try: print (a)Try: matrix(a,6,7)Try: seats <- 1:20Try: dim(seats) <- c(2,10) Try: print (seats)
Access Values
Try: print(seats)Try: seats[2,3] Try: seats[2,]Try: seats[1,]Try: seats[,3]Try: seats[,5:9]
Matrix Try: MATD <-matrix(1:6,2)Try: MATE <-matrix(c(rep(1,3), rep(2,3)), 2, byrow=T)Try: MATE+MATDTry: MATD+10Try: MATD-10Try: MATD+10Try: MATDTry: MATE-MATETry: MATD-MATETry: solve(MATD[,2:3])Try: t(MATE)Try: MATD %*% t(MATE)Try: MATD*100Try: MATD/MATE
Factors Try: data = c(1,2,2,3,1,3,2,2,3,3,3,2,2,1,2)Try: fdata=factor(data)Try: fdataTry: mean(data)
Import Data CSV1. Find the file path 2. mydata <-read.table(”filepath”,
header=T, sep=“,”)3. mydata <-read.table(”filepath”,
header=T, sep=“\t”)4. For fixed width use read.fwf
Import Data SPSS1. Install.packages(“m
emisc”)2. library(“memisc”)3. mydata <-
as.data.set(spss.system.file('/CSSE R Workshop/GEDU6100dataset.sav'))
4. mydata
data.frame strstr(mydata)
data.frame summarysummary(mydata)
data.frame fixfix(mydata)
Ways of calling your data- Mean
(mydata$MATH)
- With(mydata, mean(MATH))
- t.test(MATH~GENDER, data=mydata)
data.frame attachattach(mydata)mean(MATH)t.test(MATH~GENDER)
Export write.table(mydata, “filepath/mydata.txt”)
Note: for export to exl, SAS, SPSS you may need to use foreign package.
On your own
Try: data()- Find a data
set and str, summary & one statistical application
Useful Packages foreign HmiscprettyR psych ggplot2
summary(mydata describe(mydata)freq(mydata)rcorr(cbind (v1,v2,v3,v4)cor.test (v1,v2, use=“pairwise”)
Try this last one… Try: contour(volcano)Try: persp(volcano, expand=0.2)
Online resources http://tryr.codeschool.com
http://www.ats.ucla.edu/stat/r/faq/inputdata_R.htm
http://www.r-project.org/
https://www.stat.auckland.ac.nz/~paul/RGraphics/rgraphics.html
Good Luck!