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From Sean Owen <sro...@gmail.com>
Subject Re: Taste and MySQL with GroupLens dataset
Date Wed, 29 Jul 2009 22:47:00 GMT
Interesting, that is a complicated bit of code.

By any chance are you using ints as keys? that could suggest an explanation.

I don't suppose the data might be changing underneath you here?

On Wed, Jul 29, 2009 at 9:56 PM, Nico Higgs<elhansa@gmail.com> wrote:
> Hi Sean and everybody!
>
> I've download Mahout from SVN and followed the FAQ for trying Taste with the
> 1M ratings from GroupLens dataset test. First I tried With the
> GroupLensRecommender(that uses a FileDataModel) and everythings went ok.
>
> Then I decide to give a try with the data loaded on MySQL with the Slopone
> Recommender. After inserting the ratings.dat in taste_preferences table
> (1000029 rows), and the first run (3 hours and a half to generate the
> 4922072 rows for the slopeone diffs), I tried to get a recommend but a I'm
> getting this error in
> the getDiffs method of AbstractJDBCDiffStorage (with the userID=1 and
> howMany=5)
>
> Caused by: java.lang.ArrayIndexOutOfBoundsException: 53
>    at
> org.apache.mahout.cf.taste.impl.recommender.slopeone.jdbc.AbstractJDBCDiffStorage.getDiffs(AbstractJDBCDiffStorage.java:175)
>    at
> org.apache.mahout.cf.taste.impl.recommender.slopeone.SlopeOneRecommender.doEstimatePreference(SlopeOneRecommender.java:136)
>    at
> org.apache.mahout.cf.taste.impl.recommender.slopeone.SlopeOneRecommender.access$100(SlopeOneRecommender.java:50)
>    at
> org.apache.mahout.cf.taste.impl.recommender.slopeone.SlopeOneRecommender$Estimator.estimate(SlopeOneRecommender.java:219)
>    at
> org.apache.mahout.cf.taste.impl.recommender.slopeone.SlopeOneRecommender$Estimator.estimate(SlopeOneRecommender.java:209)
>
>
> Looking at the code it seems, that the set containg the results of the
> diffSQL contains distinct or more data than the preferences of the user. Is
> this possible?
>
> Thanks and regards!
>
> PD: I'm currently starting with taste so I don't know If i could give any
> more help. Nevetherless I will continue to investigate further the problem
> and tell you If I found something.
>

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