Github user aray commented on a diff in the pull request:
https://github.com/apache/spark/pull/16483#discussion_r106546448
--- Diff: graphx/src/main/scala/org/apache/spark/graphx/lib/PageRank.scala
---
@@ -322,13 +335,12 @@ object PageRank extends Logging {
def personalizedVertexProgram(id: VertexId, attr: (Double, Double),
msgSum: Double): (Double, Double) = {
val (oldPR, lastDelta) = attr
- var teleport = oldPR
- val delta = if (src==id) resetProb else 0.0
- teleport = oldPR*delta
-
- val newPR = teleport + (1.0 - resetProb) * msgSum
- val newDelta = if (lastDelta == Double.NegativeInfinity) newPR else
newPR - oldPR
- (newPR, newDelta)
+ val newPR = if (lastDelta == Double.NegativeInfinity) {
--- End diff --
I'm guessing you mean the `if (src==id)` check? I'm honestly not sure what
was going on with this code its just wrong. The results do not match up with
igraph/networkx at all. Furthermore the code is just nonsensical -- definition
of `var teleport = oldPR` that is then unconditionally set two lines down to
`teleport = oldPR*delta` without being used prior.
This revised implementation is much easier to follow and is now tested
against 3 sets of reference values computed by igraph/networkx. Please let me
know if you thing I'm missing something.
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