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https://issues.apache.org/jira/browse/MAHOUT-1464?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14031292#comment-14031292
 ] 

ASF GitHub Bot commented on MAHOUT-1464:
----------------------------------------

Github user dlyubimov commented on a diff in the pull request:

    https://github.com/apache/mahout/pull/18#discussion_r13775208
  
    --- Diff: 
math-scala/src/main/scala/org/apache/mahout/math/scalabindings/MatrixOps.scala 
---
    @@ -188,8 +188,8 @@ object MatrixOps {
         def apply(f: Vector): Double = f.sum
       }
     
    -  private def vectorCountFunc = new VectorFunction {
    -    def apply(f: Vector): Double = f.aggregate(Functions.PLUS, 
Functions.greater(0))
    +  private def vectorCountNonZeroElementsFunc = new VectorFunction {
    +    def apply(f: Vector): Double = f.aggregate(Functions.PLUS, 
Functions.notEqual(0))
    --- End diff --
    
    i mean, shouldn't this specialized version be more effective than an 
aggregate: 
    
        def apply(f: Vector): Double = f.getnumNonZeroElements().toDouble


> Cooccurrence Analysis on Spark
> ------------------------------
>
>                 Key: MAHOUT-1464
>                 URL: https://issues.apache.org/jira/browse/MAHOUT-1464
>             Project: Mahout
>          Issue Type: Improvement
>          Components: Collaborative Filtering
>         Environment: hadoop, spark
>            Reporter: Pat Ferrel
>            Assignee: Pat Ferrel
>             Fix For: 1.0
>
>         Attachments: MAHOUT-1464.patch, MAHOUT-1464.patch, MAHOUT-1464.patch, 
> MAHOUT-1464.patch, MAHOUT-1464.patch, MAHOUT-1464.patch, run-spark-xrsj.sh
>
>
> Create a version of Cooccurrence Analysis (RowSimilarityJob with LLR) that 
> runs on Spark. This should be compatible with Mahout Spark DRM DSL so a DRM 
> can be used as input. 
> Ideally this would extend to cover MAHOUT-1422. This cross-cooccurrence has 
> several applications including cross-action recommendations. 



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