

In [12]:

    
import networkx as nx
import random
%matplotlib inline
G = nx.Graph()
G.add_nodes_from([5,6,7])
G.add_edges_from([(7,1),(6,7),(1,5)])

Edge attributes

You might have noticed that each edge is in fact a dictionary:



In [13]:

    
G[1]   #Each node is a dictionary key. The value is another dictionary: whose keys are all the nodes it is connected to









    Out[13]:





{5: {}, 7: {}}



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G[1][5]  #There's an empty dictionary corresponding to every edge









    Out[14]:





{}

And one can store values in that, for example, edge weights:



In [15]:

    
G[1][5]['weight']=5



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for u,v in G.edges():
    G[u][v]['weight']=random.randint(1,5)



In [17]:

    
nx.draw(G,edge_color=[G[u][v]['weight'] for u,v in G.edges()])



In [18]:

    
G.edges(data=1)









    Out[18]:





[(1, 5, None), (1, 7, None), (6, 7, None)]

Node attributes



In [19]:

    
G.node[5]









    Out[19]:





{}



In [20]:

    
G.node[1]['size']=800
G.node[7]['size']=700
G.node[6]['size']=400
G.node[5]['size']=300



In [21]:

    
nx.draw(G, node_size=[G.node[n]['size'] for n in G.nodes()])

Shortest paths



In [22]:

    
AG=nx.read_gpickle("../data/smaller_airportnet.pickle")
nx.draw(AG, pos=nx.layout.circular_layout(AG))









    



---------------------------------------------------------------------------
FileNotFoundError                         Traceback (most recent call last)
<ipython-input-22-41d4f2e37c87> in <module>()
----> 1 AG=nx.read_gpickle("../data/smaller_airportnet.pickle")
      2 nx.draw(AG, pos=nx.layout.circular_layout(AG))

<decorator-gen-297> in read_gpickle(path)

/home/jana/anaconda3/lib/python3.5/site-packages/networkx/utils/decorators.py in _open_file(func, *args, **kwargs)
    196         if is_string_like(path):
    197             ext = splitext(path)[1]
--> 198             fobj = _dispatch_dict[ext](path, mode=mode)
    199             close_fobj = True
    200         elif hasattr(path, 'read'):

FileNotFoundError: [Errno 2] No such file or directory: '../data/smaller_airportnet.pickle'



In [ ]:

    
AG.edges(data=True)



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nx.shortest_path_length(AG, 'YYZ', 'ADD')



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[p for p in nx.shortest_paths.all_shortest_paths(AG,'YYZ', 'ADD')]

By default, networkx doesn't look at edge weights when calculating shortest paths



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nx.shortest_path_length(AG, 'YYZ', 'ADD', weight='weight')



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[p for p in nx.shortest_paths.all_shortest_paths(AG,'YYZ', 'ADD', weight='weight')]

Cycles



In [ ]:

    
nx.cycle_basis(AG)

Reading/writing graphs

Networkx supports reading and writing graphs in various formats:



In [ ]:

    
nx.write_edgelist(G, 'test_graph.edgelist')



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cat test_graph.edgelist



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nx.write_graphml(G, 'test_graph.graphml')



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cat test_graph.graphml



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H=nx.read_graphml("test_graph.graphml")



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H.nodes()

By default, networkx reads node labe;ls as strings, but it's easy to override:



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H=nx.read_graphml("test_graph.graphml", node_type=int)



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H.nodes()

Our recommendation: gpickle



In [ ]:

    
nx.write_gpickle(G, "test_graph.gpickle")



In [ ]:

    
H=nx.read_gpickle("test_graph.gpickle")



In [ ]:

    
H.nodes()