Martin Illecker created HAMA-904:
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Summary: 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
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? (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
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