[BUG] Non-specified nodes do not receive zero personalisation value in PageRank

[ghost]

NetworkX implements Personalised PageRank in such a way that any non-specified nodes receive a personalisation value of zero. [NX implementation]

In cuGraph, the user has to explicitly set the personalisation values for all other nodes to zero, or the results acquired do not seem to match those produced by NetworkX. If this is intended behaviour, it would be useful for the documentation to be updated making the difference clearer.

[afender]

Hi @nmkatri,

@kaatish and I were looking into this issue earlier and found that any non-specified nodes should receive a personalization value of zero in cuGraph too:

cugraph/cpp/src/link_analysis/pagerank.cu

Line 160 in bc48a35

} else {

We also have tests running nightly and comparing personalized PageRank against NetworkX output and did not catch any mismatch recently.

We would like to investigate further and have the following questions at this time :

1. Do you have steps and code to repro?
2. Are you passing a personalization subset without setting any specified personalization values? cuGraph should currently fall back on regular Pagerank if that's the case.

[ghost]

Hi @afender,

Thank you very much for looking into this. I examined my code again and the mismatch seems to be caused by something other than cuGraph's personalised PageRank. This could very well be a bug in my code, but I haven't been able to pinpoint the exact cause yet.

In the process, though, I realised that running PageRank on a weighted network (like mine) produces results that don't match NX's. Here is the code and data to reproduce the issue: reprod.zip Please let me know if there's an issue with the code I'm using. In the meantime, I will continue investigating the original issue and keep you updated.

[kaatish]

Hi @nmkatri thanks for getting back. Unfortunately as we have mentioned in the documentation, our pagerank implementation does not make use of the edge weights.

If you do feel that it is an immediately required feature for you, please feel free to file a separate issue.

[barondra]

Dear @kaatish,
I have filed an issue #1313 regarding of edge weights for PPR. Please kindly give attention to the problem.
Thank you!
Edit: Issue #1313 has been addressed