python 2.7 - how to draw multigraph in networkx using matplotlib or graphviz

Question

when I pass multigraph numpy adjacency matrix to networkx (using from_numpy_matrix function) and then try to draw the graph using matplotlib, it ignores the multiple edges.

how can I make it draw multiple edges as well ?

Answer 1

Graphviz does a good job drawing parallel edges. You can use that with NetworkX by writing a dot file and then processing with Graphviz (e.g. neato layout below). You'll need pydot or pygraphviz in addition to NetworkX

In [1]: import networkx as nx

In [2]: G=nx.MultiGraph()

In [3]: G.add_edge(1,2)

In [4]: G.add_edge(1,2)

In [5]: nx.write_dot(G,'multi.dot')

In [6]: !neato -T png multi.dot > multi.png

On NetworkX 1.11 and newer, nx.write_dot doesn't work as per issue on networkx github. The workaround is to call write_dot using

from networkx.drawing.nx_pydot import write_dot

or

from networkx.drawing.nx_agraph import write_dot