Initialize Lattices with networkx.Graphs

[Cryoris]

What should we add?

It would be nice to allow the initialization on Lattices not only with retworkx graphs but also with networks graphs. Networkx, to date, still has a lot more features and pre-defined graphs that users have access to, and is probably the standard graph library in Python.

[mtreinish]

I agree with everything in this issue, I would appreciate issues being opened on retworkx when you encounter a feature gap. Mainly because we'd like retworkx to be usable everywhere and we can prioritize features needed for a real use case. It's hard to know which functionality to prioritize without requests from users.

As an aside the current dev branch has a bunch of new graph generators, you can see the list here: https://qiskit.org/documentation/retworkx/dev/api.html#generators although I don't think any are really applicable to lattices. @k-tamuraphys has already requested some additional functionality here: Qiskit/rustworkx#150 (comment) which might not make it into 0.11 but definitely will be a priority for 0.12.

[Cryoris]

This issue is not mainly because I was encountering a particular feature gap, but I was more generally concerned about supporting networkx since it's more standardized 🙂