pylecture3 -json-

Basic NetworkX

› Adding node(s), edges(s) to a graph

› Drawing graphs

› Networks characteristics

Degree distribution

› Creating network of Twitter

Dictionaries – compound data type

Found in other languages as “map”, “associative memories”, or “associative arrays”

Lists vs Dictionaries › You can use only integer number as index on lists

Like a[0], a[-1]

› You can use integer numbers and strings as key on dictionaries(if its value exists)

Like d[0], d[‘foo’], d[‘bar’]

Creating a dictionary tel = {‘John’:0000, ‘Jane’:0001, ‘Joe’:0002}

Adding key and value tel[‘Joan’] = 0003 Getting value from key tel[‘Jane’]

Setting value from key tel[‘Joe’] = 0004 Removing value from key del tel[‘John’] Getting key list of a dictionary

tel.keys()

you can nest dictionaries, like

data = {‘one’: {‘one’: 11, ‘two’: 12}, ‘two’: {‘one’: 21, ‘two’: 22}}

print data[‘one’][‘two’]

Also, you can combine lists and dictionaries, like

data = {‘employees’:[

{‘firstName’: ‘John’, ‘lastName’: ‘Doe’},

{‘firstName’: ‘Anna’, ‘lastName’: ‘Smith’},

{‘firstName’: ‘Peter’, ‘lastName’: ‘Jones’}

]

print data[‘employees’][2][‘firstName’]

JSON (JavaScript Object Notation) is a

lightweight data-interchange format.

It is easy for humans to read and write.

It is easy for machines to parse and

generate.

From http://json.org/

A collection of name/value pairs. In various languages, this is realized as an object, record, struct, dictionary, hash table, keyed list, or associative array.

An ordered list of values. In most languages, this is realized as an array, vector, list, or sequence.

From http://json.org/

{"employees":[

{"firstName":"John", "lastName":"Doe"},

{"firstName":"Anna", "lastName":"Smith"},

{"firstName":"Peter", "lastName":"Jones"}

]}

Example from

http://www.w3schools.com/json/

import json

Load json from raw string

data = json.loads(‘{"employees":[

{"firstName":"John", "lastName":"Doe"}, {"firstName":"Anna", "lastName":"Smith"}, {"firstName":"Peter", "lastName":"Jones"} ]}’

print data[‘employees’][2][‘firstName’]

From json file(save previous json as sample.json)

with open(‘sample.json’, ‘r’) as f:

data = json.load(f)

print data[‘employees’][2][‘firstName’]

From url

Import urllib2

data = json.load(urllib2.urlopen(‘http://time.jsontest.com’))

print ‘Today is’, data[‘date’]

http://www.ebay.com/

An online auction and shopping site

HTTP GET URL(search items that its keyword is “harry potter phoenix” http://svcs.ebay.com/services/search/FindingService/v1?

OPERATION-NAME=findItemsByKeywords

&SERVICE-VERSION=1.0.0

&SECURITY-APPNAME=YourAppID

&RESPONSE-DATA-FORMAT=json

&REST-PAYLOAD

&keywords=harry%20potter%20phoenix

YourAppID have to be replaced

More Information: › http://developer.ebay.com/Devzone/finding/Concepts/MakingACall.html

› http://developer.ebay.com/Devzone/finding/CallRef/index.html

https://github.com/

An online software development

environment

HTTP GET URL(searches repositories(projects) that its keyword

is “tetris” and written in assembly language)

https://api.github.com/search/repositories?

q=tetris+language:assembly

&sort=stars

&order=desc

More information:

› https://developer.github.com/v3/

› https://developer.github.com/v3/search/

Saving

import networkx as nx

import pickle

G = Graph()

# some works here

pickle.dump(G, open(‘your_graph.txt’, ‘w’))

Loading

G = pickle.load(open(‘your_graph.txt’, ‘r’))

Dictionaries(Python data structure)

Brief explanation of JSON

Getting JSON Data › From raw string

› From JSON file

› From URL

Example: eBay and GitHub

Saving/loading networks