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https://issues.apache.org/jira/browse/HAMA-904?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Martin Illecker updated HAMA-904:
---------------------------------

    Description: 
*Fix Collaborative Filtering Example and revise test case.*

I had a deep look into the collaborative filtering example of Ikhtiyor Ahmedov 
\[1] and found the following questions / problems:

 - Why are user and item features broadcasted \[2] by each peer and not shared 
by a global input file on HDFS? (possible performance increase?)

 - Use o.a.h.c.u.KeyValuePair instead of commons.math3.util.Pair in 
UserSimilarity \[3] and ItemSimilarity \[4]

 - No need for normalizeWithBroadcastingValues \[5] when taskNum = 1

 - Why are values sent to itself and received later? \[6] (possible performance 
increase?)

 - Why is every task saving all items? \[7] (duplicate saves?)

 - Why is the default ALPHA value 0.01 and not 0.001? \[8] (if (matrixRank > 
250) -> Infinite / NaN)

I hope Ikhtiyor Ahmedov will finally become a committer and helps us to solve 
these questions.
Thanks!

\[1] https://issues.apache.org/jira/browse/HAMA-612
\[2] 
https://github.com/apache/hama/blob/trunk/ml/src/main/java/org/apache/hama/ml/recommendation/cf/OnlineTrainBSP.java#L116-128
\[3] 
https://github.com/apache/hama/blob/trunk/ml/src/main/java/org/apache/hama/ml/recommendation/UserSimilarity.java#L22
\[4] 
https://github.com/apache/hama/blob/trunk/ml/src/main/java/org/apache/hama/ml/recommendation/ItemSimilarity.java#L22
\[5] 
https://github.com/apache/hama/blob/trunk/ml/src/main/java/org/apache/hama/ml/recommendation/cf/OnlineTrainBSP.java#L138
\[6] 
https://github.com/apache/hama/blob/trunk/ml/src/main/java/org/apache/hama/ml/recommendation/cf/OnlineTrainBSP.java#L323
\[7] 
https://github.com/apache/hama/blob/trunk/ml/src/main/java/org/apache/hama/ml/recommendation/cf/OnlineTrainBSP.java#L387-422
\[8] 
https://github.com/apache/hama/blob/trunk/ml/src/main/java/org/apache/hama/ml/recommendation/cf/function/MeanAbsError.java#L62

  was:
*Fix Collaborative Filtering Example and revise test case.*

I had a deep look into the collaborative filtering example of Ikhtiyor Ahmedov 
\[1] and found the following questions / problems:

 - Why are user and item features broadcasted \[2] by each peer and not shared 
by a global input file on HDFS? (possible performance increase?)

 - Use o.a.h.c.u.KeyValuePair instead of commons.math3.util.Pair in 
UserSimilarity \[3] and ItemSimilarity \[4]

 - No need for normalizeWithBroadcastingValues \[5] when taskNum = 1

 - Why are values sent to itself and received later? \[6] (possible performance 
increase?)

 - Why is every task saving all items? (duplicate saves?)

 - Why is the default ALPHA value 0.01 and not 0.001? (if (matrixRank > 250) -> 
Infinite / NaN)

I hope Ikhtiyor Ahmedov will finally become a committer and helps us to solve 
these questions.
Thanks!

\[1] https://issues.apache.org/jira/browse/HAMA-612
\[2] 
https://github.com/apache/hama/blob/trunk/ml/src/main/java/org/apache/hama/ml/recommendation/cf/OnlineTrainBSP.java#L116-128
\[3] 
https://github.com/apache/hama/blob/trunk/ml/src/main/java/org/apache/hama/ml/recommendation/UserSimilarity.java#L22
\[4] 
https://github.com/apache/hama/blob/trunk/ml/src/main/java/org/apache/hama/ml/recommendation/ItemSimilarity.java#L22
\[5] 
https://github.com/apache/hama/blob/trunk/ml/src/main/java/org/apache/hama/ml/recommendation/cf/OnlineTrainBSP.java#L138
\[6] 
https://github.com/apache/hama/blob/trunk/ml/src/main/java/org/apache/hama/ml/recommendation/cf/OnlineTrainBSP.java#L323


> Fix Collaborative Filtering Example
> -----------------------------------
>
>                 Key: HAMA-904
>                 URL: https://issues.apache.org/jira/browse/HAMA-904
>             Project: Hama
>          Issue Type: Bug
>          Components: examples, machine learning
>    Affects Versions: 0.6.4
>            Reporter: Martin Illecker
>            Priority: Minor
>              Labels: collaborative-filtering, examples, machine_learning
>             Fix For: 0.7.0
>
>
> *Fix Collaborative Filtering Example and revise test case.*
> I had a deep look into the collaborative filtering example of Ikhtiyor 
> Ahmedov \[1] and found the following questions / problems:
>  - Why are user and item features broadcasted \[2] by each peer and not 
> shared by a global input file on HDFS? (possible performance increase?)
>  - Use o.a.h.c.u.KeyValuePair instead of commons.math3.util.Pair in 
> UserSimilarity \[3] and ItemSimilarity \[4]
>  - No need for normalizeWithBroadcastingValues \[5] when taskNum = 1
>  - Why are values sent to itself and received later? \[6] (possible 
> performance increase?)
>  - Why is every task saving all items? \[7] (duplicate saves?)
>  - Why is the default ALPHA value 0.01 and not 0.001? \[8] (if (matrixRank > 
> 250) -> Infinite / NaN)
> I hope Ikhtiyor Ahmedov will finally become a committer and helps us to solve 
> these questions.
> Thanks!
> \[1] https://issues.apache.org/jira/browse/HAMA-612
> \[2] 
> https://github.com/apache/hama/blob/trunk/ml/src/main/java/org/apache/hama/ml/recommendation/cf/OnlineTrainBSP.java#L116-128
> \[3] 
> https://github.com/apache/hama/blob/trunk/ml/src/main/java/org/apache/hama/ml/recommendation/UserSimilarity.java#L22
> \[4] 
> https://github.com/apache/hama/blob/trunk/ml/src/main/java/org/apache/hama/ml/recommendation/ItemSimilarity.java#L22
> \[5] 
> https://github.com/apache/hama/blob/trunk/ml/src/main/java/org/apache/hama/ml/recommendation/cf/OnlineTrainBSP.java#L138
> \[6] 
> https://github.com/apache/hama/blob/trunk/ml/src/main/java/org/apache/hama/ml/recommendation/cf/OnlineTrainBSP.java#L323
> \[7] 
> https://github.com/apache/hama/blob/trunk/ml/src/main/java/org/apache/hama/ml/recommendation/cf/OnlineTrainBSP.java#L387-422
> \[8] 
> https://github.com/apache/hama/blob/trunk/ml/src/main/java/org/apache/hama/ml/recommendation/cf/function/MeanAbsError.java#L62



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