PyLecture2 -NetworkX-

 Basic Python
› Data types(Integer, String, List)
› Control flow statements
› List comprehension

 Import NetworkX
import networkx as nx
 Generating a graph
G = nx.Graph()
 Adding a node
G.add_node(“one”)
 Adding nodes
G.add_nodes_from([“two”, “three”])
 Adding an edge
G.add_edge(“one”, “two”)
 Adding edges
G.add_edges_from([(“two”, “three”), (“three”, “one”)])

import matplotlib.pyplot as plt
nx.draw(G)
plt.show()

 Path graphs
› G = nx.path_graph(40)
 Cycle graphs
› G = nx.cycle_graph(40)
 Complete graphs
› G = nx.complete_graph(40)
 2D grid graphs
› G = nx.grid_2d_graph(5, 4)
 Random graphs
› G = nx.erdos_renyi_graph(20, 0.3)
› G = nx.barabasi_albert_graph(100, 5)

 The number of degrees
› len(G.nodes())
 The number of edges
› len(G.edges())
 Average degree
› 2 * len(G.edges()) / len(G.nodes())
 Average path length
› Gsub = nx.connected_component_subgraphs(G)[0]
› nx.average_shortest_path_length(G)
 Network density
› nx.density(G)

deg = [nx.degree(G,n) for n in G.nodes()]
hist = [0 for i in range(max(deg)+1)]
for d in deg:
hist[d] += 1
plt.plot(range(len(hist)), hist, "or")
plt.show()

 Go to http://apps.twitter.com and create your app .
› You will get API Key, API Secret, Access Token, and Access Token Secret.
 Installing tweepy
› pip install tweepy

 Next, many, many lines of python code
 You can get the python script(named
Tweepy1.py) at
https://codebreak.com/git/arity/TweepyTutori
al/tree/master/

import time
import tweepy
# Copy the api key, the api secret, the access token and the access
# token secret from the relevant page on your Twitter app
api_key = ‘your_api_key_here'
api_secret = ‘your_api_secret_here’
access_token = ‘your_access_token_here'
access_token_secret = ‘your_access_token_secret_here'
# You don't need to make any changes below here
# This bit authorises you to ask for information from Twitter
auth = tweepy.OAuthHandler(api_key, api_secret)
auth.set_access_token(access_token, access_token_secret)
# The api object gives you access to all of the http calls that Twitter accepts
api = tweepy.API(auth)

def fib(n,user,network):
if n>0:
time.sleep(40)
try:
users=api.followers(user)
except tweepy.TweepError:
return
for follower in users:
network.add_node(follower.screen_name)
network.add_edge(follower.screen_name, user)
fib(n-1,follower.screen_name,network)

#Then, There is a directed graph
G = nx.DiGraph()
#User we want to use as initial node
user='GitHub‘
G.add_node(user)
n=2
fib(n,user,G)
nx.draw(G)
plt.show()

 Graph manipulating functions
› Adding nodes, edges
 Many types of network
 Many network characteristics

PyLecture2 -NetworkX-

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