[jira] [Comment Edited] (SPARK-7005) resetProb error in pagerank

["lisendong (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SPARK-7005?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14502310#comment-14502310 ] 

lisendong edited comment on SPARK-7005 at 4/20/15 3:45 AM:
-----------------------------------------------------------

I don't think so.
because pagerank is  a iteration algorithm, the resetProb is alpha/N , but the code multiply this prob by N...
which causes the result quite different.






was (Author: lisendong):
I don't think so.
because pagerank is  a iteration algorithm, the recetProb is alpha/N , but the code multiply this prob by N...
which causes the result quite different.





> resetProb error in pagerank
> ---------------------------
>
>                 Key: SPARK-7005
>                 URL: https://issues.apache.org/jira/browse/SPARK-7005
>             Project: Spark
>          Issue Type: Bug
>          Components: MLlib
>    Affects Versions: 1.3.0
>            Reporter: lisendong
>              Labels: easyfix
>   Original Estimate: 24h
>  Remaining Estimate: 24h
>
> in the page rank code, the resetProb should be divided by #vertex according to the wikipedia:
> http://en.wikipedia.org/wiki/PageRank
> that is: 
> PR[i] = alpha / N + (1 - alpha) * inNbrs[i].map(j => oldPR[j] / outDeg[j]).sum
> but the code is (org.apache.spark.graphx.lib.PageRank)
> PR[i] = alpha + (1 - alpha) * inNbrs[i].map(j => oldPR[j] / outDeg[j]).sum



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