[ https://issues.apache.org/jira/browse/MAHOUT-1185?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Cunlu Zou updated MAHOUT-1185: ------------------------------ Attachment: MemoryDiffStorage.patch Sorry, I made a mistake on the length, here is the correct patch > 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 > Labels: patch > 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. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira