WIP: Implement Incremental Topological Sort (Issue 1457)

[aweltsch]

I started to add an algorithm that can be used to incrementally update the topological sorting of a directed graph. I'm not 100% content with the API design. It would be great to get some feedback.

I am particularly concerned with the placement of the corresponding data structure (class IncrementalTopologicalSort). Is the dag.py file the right place?

Also I wondering if I should derive the class from the nx.DiGraph or something like that.

Any additional feedback is greatly appreciated!
Thank you!

[dschult]

Can you provide a short description of the goal of this feature? What are you trying to achieve relative to the existing algorithms for topological sort (that is -- why create an incremental system)?
The next question is whether you are implementing the published algorithm's data structures as well as program flow. I haven't read it, but your question about whether it should subclass nx.DiGraph might be answered by whether the paper uses a graph-like data structure.

Thanks!

[MridulS]

Thanks for your work @aweltsch!

This hasn't been touched in a while. I will go ahead and close this for now. Thanks again for your contributions!