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From "Mugoma Joseph Okomba" <mug...@yengas.com>
Subject Re: Exclusing certain ratings when running recommender
Date Wed, 09 May 2012 09:09:36 GMT

If it's true that IDRescorer works on original items then that's both bad
and good news for me.

The bad news is is that all the code I had previous written involving
IDRescorer is all bugy since I had assumed that IDRescorer filters
recommendations and not original list

The bit of good news is that I don't have to anything for the new task.

But, if IDRescorer changes original list, what can be used to change
recommendations?

On Wed, May 9, 2012 11:14 am, Sean Owen wrote:
> Trust me, I'm telling you how it works since I wrote it. What is unclear
> about the steps I listed below?
>
> Filtering happens before even *scoring*. It works exactly how you want it
> to. If you're still confused please just read the source code.
>
> On Wed, May 9, 2012 at 9:08 AM, Mugoma Joseph Okomba
> <mugoma@yengas.com>wrote:
>
>>
>> From javadoc
>> (
>> https://builds.apache.org/job/Mahout-Quality/javadoc/org/apache/mahout/cf/taste/impl/recommender/GenericUserBasedRecommender.html#recommend(long,%20int,%20org.apache.mahout.cf.taste.recommender.IDRescorer)
>>
>> rescorer - rescoring function to apply before final list of
>> recommendations is determined
>>
>> My take is that IDRescorer is used to determine the final list of
>> recommendations (via filtering or re-scoring) but doesn't apply on the
>> original items.
>>
>> To be clear let me give small demonstration:
>> 1. Item 1 => rating 3
>> 2. Item 2 => rating 2
>> 3. Item 3 => rating 1
>> 4. Item 4 => rating 3
>> 5. Item 5 => rating 2
>> 6. Item 6 => rating 4
>> 7. Item 7 => rating 2
>> 8. Item 8 => rating 3
>> 9. Item 9 => rating 4
>> 10. Item 10 => rating 4
>>
>> Original items => 10
>>
>> What IDRescorer does is compute recommendations then exclude items 6,9 &
>> 10 from final list via filtering.
>>
>> What I need is that, before recommendations are computed, only items
>> 1,2,3,4,5,7,8 are considered i.e. original items should be reduced from
>> 10
>> to 7 and only the 7 items should be considered by the recommender.
>>
>>
>



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