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From Sebastian Schelter <>
Subject Re: Need for a distributed SVDRecommender
Date Fri, 19 Nov 2010 22:27:37 GMT
>> So my doubt is do we have a distributed SVDRecommender implementation? If
>> not, how should i go about writing one? 

The algorithm in MAHOUT-542 performs a distributed matrix factorization
that shall be used for recommendations one day. However it is in a very
early stage and it has not even been verified yet that the
implementation is working correctly. If you wanna help with it that
would be great.

Can I use the new LanczosSolver to
>> achieve this?

The paper "Large-scale Parallel Collaborative Filtering for the Netflix
Prize" says that you can't use Lanczos to factorize a rating matrix as
it is only partially specified. However someone with more mathematical
expertise than me should validate that statement, hope I didn't get that
wrong :)

Ted is working on LatentFactorLogLinear models in MAHOUT-525 which can
be used for recommendations too and should be superior to the approach
of MAHOUT-542. They're not distributed but in the paper in which they
are described the authors state that they could train the 1M Movielens
Dataset in 7 minutes so they should be fast enough for your testcase.


>> Thanks,
>> Sanjib

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