Counting number of bidirectional edges of a Graph

[Jose Guzman]

Hi everybody,

I've just started to use networkx and when checked the documentation I could not find whether there is an algorithm to count the number bidirectional edges between nodes. For example:

>>> import networkx as nx
>>> G = nx.DiGraph()
>>> G.add_edges_from([(0,1),(1,0),(1,2)])
>>> G.size() # returns 3

it would expect to have 1 bidirectional node (0,1), (1,0).

Thanks in advance.

Jose

[Dan Schult]

There is no built-in method to count bidirectional edges in a DiGraph.
But you could build one quickly with something like:

0.5 * len( [ 1 for (u,v) in G.edges() if u in G[v] ] )

Dan

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[Moritz Beber]

I'd include a check to avoid counting self-loops.