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https://issues.apache.org/jira/browse/MAHOUT-1185?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13619752#comment-13619752
]
Hudson commented on MAHOUT-1185:
--------------------------------
Integrated in Mahout-Quality #1945 (See
[https://builds.apache.org/job/Mahout-Quality/1945/])
MAHOUT-1185 ensure last item's value is counted in average (not diffs)
(Revision 1463463)
Result = SUCCESS
srowen : http://svn.apache.org/viewcvs.cgi/?root=Apache-SVN&view=rev&rev=1463463
Files :
*
/mahout/trunk/core/src/main/java/org/apache/mahout/cf/taste/impl/recommender/slopeone/MemoryDiffStorage.java
> MemoryDiffStorage.class has a bug for slope one algorithm which could cause
> incorrect recommendation results
> ------------------------------------------------------------------------------------------------------------
>
> Key: MAHOUT-1185
> URL: https://issues.apache.org/jira/browse/MAHOUT-1185
> Project: Mahout
> Issue Type: Bug
> Components: Collaborative Filtering
> Affects Versions: 0.7
> Environment: Ubuntu
> Reporter: Cunlu Zou
> Assignee: Sean Owen
> Priority: Minor
> Fix For: 0.8
>
> Attachments: MemoryDiffStorage.patch, MemoryDiffStorage.patch
>
> Original Estimate: 10m
> Remaining Estimate: 10m
>
> The function processOneUser(long averageCount, long userID) in the
> MemoryDiffStorage.class file contains a bug for calculating the itemAverage.
> Since the function tried to calculate the average difference among items (in
> a nested loop) and also the average individual item preference value in the
> same loop (the loop only from 0 to length-2, *for (int i = 0; i < length - 1;
> i++)*), the itemAverage variable does not count the last item's preference
> value for every users which could lead to an incorrect recommendation results.
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