Degree centrality implementation

[Gohlub]

Proposed a solution for #1129. The implementation is straightforward, though I wonder whether I should add a flag to support in-degree and out-degree centrality, and support for weighted graphs (since the current implementation assumes an unweighted graph). Let me know what you think!

[CLAassistant]

All committers have signed the CLA.

[IvanIsCoding]

Thanks for making your first contribution. I left some comments, but some things to note:

• Add release notes: https://github.com/Qiskit/rustworkx/blob/main/CONTRIBUTING.md#release-notes
• Add a universal function so your code works with both PyGraph and PyDiGraph. Here is a good example:

  rustworkx/rustworkx/__init__.py

  Line 1273 in 8774ccd

  def katz_centrality(

• You probably want to implement this centrality for PyDiGraph as well
• Format your code. It is an automated process, see https://github.com/Qiskit/rustworkx/blob/main/CONTRIBUTING.md#style

Also, I noticed from the CLA bot that this PR has two authors. This is quite unusual for a first contribution so please let me know if you are:

1. Working on a college assignment together
2. One of the users flagged by the bot is an AI Assistant

There is nothing wrong with either, but it can help me review the PR accordingly.

[IvanIsCoding]

Also, we can handle in_degree and out_degree in a separate PR. These methods would only be for PyDiGraph. They probably would reuse most of the existing code as I pointed out in the comment, but it requires more tests and all that.

[Gohlub]

Hi, thank you for the swift feedback! I just wanted to note that this was in fact a college assignment, with the other contributor being my classmate. However we are now moving on to individual work, so I will be responsible for the next steps. I will be begin addressing your suggestions shortly.

[IvanIsCoding]

Hi, thank you for the swift feedback! I just wanted to note that this was in fact a college assignment, with the other contributor being my classmate. However we are now moving on to individual work, so I will be responsible for the next steps. I will be begin addressing your suggestions shortly.

Sounds good to me, just remember to ask your classmate(s) to sign the CLA otherwise the bot will not let it get merged

[Gohlub]

I tried to rebase to amend a commit my friend made, but I think I inadvertently added things to the PR that should not be there. What is the course of action here?

[IvanIsCoding]

Keep "Maintainers are allowed to edit this pull request." active as it is right now and don't do further pushes. I will do a force push with the diff only and take it from here.

I will add you as an author and your classmate as co-author.

[IvanIsCoding]

Just to let you know about the changes I made:

• I fixed some warnings from the lint (https://github.com/Qiskit/rustworkx/blob/main/CONTRIBUTING.md#lint)
• I added type annotations (https://github.com/Qiskit/rustworkx/blob/main/CONTRIBUTING.md#type-annotations)
• The rustdoc tests were broken so I had to fix them. I removed the assertions that were incorrect, I think the proper example call is sufficient for the moment
• I handled a corner case where the graph has nodes that have been removed. Previously, we were returning centralities for removed nodes.

Nevertheless, thanks for getting this started it was a lot of help

[coveralls]

Pull Request Test Coverage Report for Build 11885136415

Details

• 87 of 87 (100.0%) changed or added relevant lines in 3 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.02%) to 95.853%

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Totals
Change from base Build 11866861155:	0.02%
Covered Lines:	18212
Relevant Lines:	19000

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💛 - Coveralls