About time-svd++ implementation

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bang le hai

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Jan 15, 2014, 11:07:07 PM1/15/14
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Hi, I'm Bang,

I have a question about the implementation of time-svd++ algorithm.
In the term which represents the perspective of implicit feedback in formula (14) - paper "Koren - Collaborative filtering with temporal dynamics",
as my understand, y_j should be a D-dimensional vector (D is the number of latent features) but in the time-svd++ implementation of graphchi, y_j is scalar.
Is this implementation of time-svd++ the same with the original implementation which can get the results reported in the paper?

Thank you,
Bang

Danny Bickson

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Jan 16, 2014, 12:53:14 AM1/16/14
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Hi Bang, 
I think you are right, our implementation is a slight variation of the paper since we have a third term in the prediction which is the https://github.com/GraphChi/graphchi-cpp/blob/master/toolkits/collaborative_filtering/timesvdpp.cpp#L168
I guess you can comment this line if you like to return to the original paper formulation.

Best, 

Danny Bickson
Co-Founder
GraphLab Inc.


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