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From "Martin Illecker (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HAMA-904) Fix Collaborative Filtering Example
Date Thu, 22 May 2014 08:54:41 GMT

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

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

    Assignee:     (was: Martin Illecker)

> 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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