Compsci 06/101, Fall 2010 11.1

What's ahead in Compsci 6/101?

Software architecture and design, why Jotto has modules and how communication works We write small programs, want to understand some

principles of larger programs Software design in the small and in the large:

different!

Dictionaries: associating keys with values Arguably the most useful method for structuring

data How does Google find 'good' sites for a query? How do we find what region in a genome encodes a

protein? How do we determine literary/other fingerprints?

Compsci 06/101, Fall 2010 11.2

Jotto: The Program Architecture

You write jottoModel.py This is the guts, brains, state of the program Keeps track of how the game is progressing Functions in the module communicate via global

state

We provide two views: command-line and GUI These all you to view and control the model Both view-controllers: jottoMain.py and jottoGui.py

know about the model, but model doesn't know about them

Model-View or Model-View-Controller Often the model knows there is/are view(s) not Jotto

Compsci 06/101, Fall 2010 11.3

Maria Klawe Chair of Computer Science at

UBC, Dean of Engineering at Princeton, President of Harvey Mudd College, ACM Fellow,…

Klawe's personal interests include

painting, long distance running, hiking, kayaking, juggling and playing electric guitar. She describes herself as "crazy about mathematics" and enjoys playing video games.

"I personally believe that the most important thing we have to do today is use technology to address societal problems, especially in developing regions"

Compsci 06/101, Fall 2010 11.4

Useful Computer Science http://maps.google.com/maps?

f=d&source=s_d&saddr=300+W+Morga n+St,+Durham,+NC+27701+(Blue+Coffee+Express)&daddr=2324+Duke +University+Road,+Durham,+NC+27708&hl=en&geocode=FcNJJQIdYw5 M-yGT6vAZOfvdQg%3B&mra=ls&sll=36.088126,-79.01786&sspn=1.333 898,2.11212

Blue Coffee ExpressDurham

2324 Duke UniversityRoad

Compsci 06/101, Fall 2010 11.5

How does this work?

http://tinyurl.com/d5o8mr

Compsci 06/101, Fall 2010 11.6

What is a dictionary, map, hash, table?

Abstraction: collection of (key,value) pairs What kind of ice-cream do you like? You are the key, ice cream is the value

RobertSusanJeffAlexBruceSam

Compsci 06/101, Fall 2010 11.7

What does this code do? How?

def fileStatsList(filename): file = open(filename) statList = [] for word in file.read().split(): found = False for pair in statList: if pair[0] == word: pair[1] += 1 found = True break if not found: statList.append([word,1]) file.close() return statList

Compsci 06/101, Fall 2010 11.8

Faster, Cheaper, Totally in Control

def fileStatsDictionary(filename): file = open(filename) stats = {} for word in file.read().split(): if word in stats: stats[word] += 1 else: stats[word] = 1 file.close() return stats

Compsci 06/101, Fall 2010 11.9

Accessing map

Index a map by a key, using […] Like indexing a list, but index is a string, …. not

integer! Works internally by associating a number with the key This association is known as hashing the key

Methods for dictionaries: .clear(), .get(key), .get(key,default) .keys(), .values(), .items()

When using iteration or x in d, we're talking keys Iterate over keys, query about keys, and so on

Compsci 06/101, Fall 2010 11.10

Literary Fingerprint

Timing and playing with code in fingerPrint.py How do we find out how fast this is? How do we change the format of the output? Can we organize output differently?

How can we find 'other' fingerprints Shazaam, genome, images What will be the key, what will be the value?