On Fri, Nov 19, 2010 at 2:27 PM, Sebastian Schelter <[email protected]> wrote:
> 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 :) > You correctly quoted the statement. But I don't think that the statement is entirely correct. The difference in practice isn't all that big a deal. > 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. > This is where I would push for recommendations. I have a preliminary implementation available on github, but I don't think it is ready to commit. It does do roughly what it is supposed to do (on one test) but I don't have enough runtime with it to have any level of confidence yet.
