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https://issues.apache.org/jira/browse/MAHOUT-305?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12837528#action_12837528
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Ted Dunning commented on MAHOUT-305:
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{quote}
Yeah in this context there's no choice but to count unrated items as misses. My
intuition based on limited experience is it is in fact an issue - are the best
items for a user typically found among their ratings in real-world data sets? I
just can't imagine it's so for most users, who express few ratings.
{quote}
This suggests that mean reciprocal rank (MRR) of the top 5 or 10 highly rated
items might be a useful measure. Even if the top 10 has several unrated good
choices, if the rated choices are all pretty high then you can have pretty good
feelings even if they didn't quite make the top 10.
> Combine both cooccurrence-based CF M/R jobs
> -------------------------------------------
>
> Key: MAHOUT-305
> URL: https://issues.apache.org/jira/browse/MAHOUT-305
> Project: Mahout
> Issue Type: Improvement
> Components: Collaborative Filtering
> Affects Versions: 0.2
> Reporter: Sean Owen
> Assignee: Ankur
> Priority: Minor
>
> We have two different but essentially identical MapReduce jobs to make
> recommendations based on item co-occurrence:
> org.apache.mahout.cf.taste.hadoop.{item,cooccurrence}. They ought to be
> merged. Not sure exactly how to approach that but noting this in JIRA, per
> Ankur.
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