convert_graph_formats() handles networkx nodes that are neither strin…

[shashank025]

…gs nor ints

Identify the Bug

• Issue convert_graph_formats() breaks for bipartite networkx graphs, where the nodes are neither strings nor ints #241

Description of the Change

As mentioned on issue #241, this change handles the scenario where the graph nodes are neither strings nor ints. This is done in two steps:

1. A dictionary that maps from a string to the underlying node is constructed, and
2. That dictionary is used to properly handle the scenario where the input graph is bipartite.

Alternate Designs

NA

Possible Drawbacks

One issue with this fix is the extra memory required to construct the dictionary. But I don't see a way around this if supporting bipartite graphs is required.

Verification Process

• Manual verification (running the repro test script with test changes),
• Added new test cases to test_utils.py.

Release Notes

Correctly handled conversion from networkx to igraph format for bipartite graphs where nodes are neither strings nor ints.