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https://issues.apache.org/jira/browse/MAHOUT-676?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13040978#comment-13040978
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Lance Norskog commented on MAHOUT-676:
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A Poisson join sampler should probably be next: decimate both legs of a join,
then decimate the remaining amount during the join.
> Random samplers in a modular library
> ------------------------------------
>
> Key: MAHOUT-676
> URL: https://issues.apache.org/jira/browse/MAHOUT-676
> Project: Mahout
> Issue Type: New Feature
> Components: Math
> Reporter: Lance Norskog
> Priority: Minor
> Attachments: MAHOUT-676.patch, Sampler.patch
>
>
> This is a modular suite of samplers. It supplies the ability to throw away
> samples in a useful way.
> Here is a use case: for my recommendations, I want user activity to decide
> the amount of influence on the results. For the number of users who watch X
> number of movies: 1-5 is 20%, 6-15 is 50%, 15-30 is 30 %, and users who watch
> over 30 movies are not useful.
> * If I know the input distribution, I can supply a function to the Slice
> sampler to give this distribution.
> * If I don't know the distribution, I can create a Reservoir sampler for each
> of the three buckets. After reading the whole set, I check the sizes of the
> various buckets and solve for my distribution. This gives the number of users
> to pull from each bucket.
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