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https://issues.apache.org/jira/browse/MAHOUT-393?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Sean Owen resolved MAHOUT-393.
------------------------------
Assignee: Sean Owen
Fix Version/s: 0.4
Resolution: Fixed
Done, I committed with only two substantive tweaks:
- I had switched over to VLongWritable from LongWritable. Most IDs used don't
really need nearly 8 bytes, so variable-length coding saves a lot.
- CountUsersKeyWritable didn't define equals() and hashCode() non-trivially,
and was inconsistent with compareTo(). Do I miss something about this?
> Distributed item similarity functions
> -------------------------------------
>
> Key: MAHOUT-393
> URL: https://issues.apache.org/jira/browse/MAHOUT-393
> Project: Mahout
> Issue Type: Improvement
> Components: Collaborative Filtering
> Reporter: Sebastian Schelter
> Assignee: Sean Owen
> Fix For: 0.4
>
> Attachments: MAHOUT-393.patch
>
>
> To complete the work started in MAHOUT-389, I've created a distributed
> version of any item similarity function that is currently already available
> in a non-distributed manner. An additional M/R job was necessary to compute
> the number of all users which is needed by some similarity functions (like
> LogLikelihoodSimilarity for example).
> There is still some optimization potential in the code as not every
> similarity function needs all information that is currently extracted (like
> the number of users e.g.), but the optimization would have made the code much
> less readable so I did not do any work on that.
> I hope you consider this a useful addition.
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