EgoNet

[afender]

Description

Let the egonet graph of a node x be the subgraph that includes the neighborhood of x and all edges between them. Here is a basic description (1-hop, single seed) :

• Add center node x to the graph.
• Go through all the neighbors y of this center node x, add edge (x, y) to the graph.
• For each neighbor y of center node x, go through all the neighbors z of center node x, if there is an edge between y and z in the original graph, add edge (y, z) to our new graph.

Proposed solution

Rather than doing custom one/two hops features, we propose a generic k-hops solution leveraging BFS with cutoff to identify neighbors within a given radius.

In addition to the single source version (matching what's available in Nx), we propose to handle multiple sources (seeds) at once which allows better performances.

This PR also enables a path in the experimental stack for returning multiple graphs (edge list format) from CUDA prims to python without using the legacy classes.

As future work, we want to enable concurrency for the cutoff BFS for each seed. This is dependent of #957

Close #475

[codecov-io]

Codecov Report

Merging #1365 (ca5b3b3) into branch-0.18 (2fb0725) will increase coverage by 0.50%.
The diff coverage is 66.66%.

@@               Coverage Diff               @@
##           branch-0.18    #1365      +/-   ##
===============================================
+ Coverage        60.38%   60.88%   +0.50%     
===============================================
  Files               67       68       +1     
  Lines             3029     3096      +67     
===============================================
+ Hits              1829     1885      +56     
- Misses            1200     1211      +11     

Impacted Files	Coverage Δ
python/cugraph/centrality/__init__.py	100.00% <ø> (ø)
python/cugraph/link_analysis/pagerank.py	100.00% <ø> (ø)
python/cugraph/comms/comms.py	34.52% <25.00%> (ø)
python/cugraph/dask/common/input_utils.py	23.07% <28.57%> (+1.14%)	⬆️
python/cugraph/utilities/utils.py	66.92% <30.76%> (-4.63%)	⬇️
python/cugraph/dask/common/mg_utils.py	37.50% <38.09%> (-2.50%)	⬇️
python/cugraph/community/spectral_clustering.py	72.54% <38.46%> (-11.67%)	⬇️
python/cugraph/structure/number_map.py	59.20% <50.00%> (+3.24%)	⬆️
python/cugraph/structure/graph.py	66.99% <76.47%> (+0.19%)	⬆️
python/cugraph/community/egonet.py	91.42% <91.42%> (ø)
... and 13 more

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[BradReesWork]

@gpucibot merge