I'm trying shoehorn a label propagation-ish algorithm into GraphX. I need to update each vertex with the median value of their neighbors. Unlike PageRank, which updates each vertex with the mean of their neighbors, I don't have a simple commutative and associative function to use for mergeMsg.
What are my options? It looks like I can choose between: 1. a hacky mergeMsg (i.e. combine a,b -> Array(a,b) and then do the median in vprog) 2. collectNeighbors and then median 3. ignore GraphX and just do the whole thing with joins (which I actually got working, but its slow) Is there another possibility that I'm missing?
