Add Link Analysis functions

[IvanIsCoding]

What is the expected enhancement?

Add functions to calculate PageRank and HITS to expand the retworkx's link analysis capabilities.

These algorithms are popular among users of graph libraries, and also appear frequently in benchmarks. The hope by adding those algorithms is to make retworkx appeal to more users and become more popular.

For inspiration, our functions couls have an API that is similar to networkx's Link Analysis API:

• pagerank
• pagerank_numpy
• hits
• hits_numpy

[mtreinish]

What about google_matrix, hub_matrix, and authority_matrix looking at those it looks like they're used internally by the functions you listed but also exposed as public functions in networkx. Do you think it makes sense to do the same for retworkx?

[IvanIsCoding]

What about google_matrix, hub_matrix, and authority_matrix looking at those it looks like they're used internally by the functions you listed but also exposed as public functions in networkx. Do you think it makes sense to do the same for retworkx?

It would be nice to expose those publicly if it is easy to do so. It also helps to keep the code organized, so we could follow networkx implemenation style and separate it as calculate matrix in one function, than interpret the eigenvectors in another function.

However, the main focus should be implementing pagerank and hits. google_matrix and hub_matrix would be a nice to have, but pagerank and hits are an order of magnitude more popular than the internals they use. For link anaylsis, what matters is more the end result.