Exporting Layout Positions for a Graph Using NetworkX

Question

After generating x/y layout coordinates for a graph in NetworkX, how do I export the graph, along with node positions, as part of the node definition using something like GraphML?

The layout algorithms don't seem to annotate the graph directly? Or do they?!

Answer 1

The layout algorithms don't set node attributes (but they should). Here is how to set the attributes:

In [1]: import networkx as nx

In [2]: G=nx.path_graph(4)

In [3]: pos=nx.spring_layout(G)

In [4]: nx.set_node_attributes(G,'pos',pos)

In [5]: G.node
Out[5]: 
{0: {'pos': array([ 0.,  0.])},
 1: {'pos': array([ 0.32267963,  0.03340727])},
 2: {'pos': array([ 0.67729057,  0.07011044])},
 3: {'pos': array([ 1.        ,  0.10350174])}}