Parallel ALS is exactly an example of where you can use matrix factorization for "0/1" data.
On Mon, May 6, 2013 at 9:22 PM, Tevfik Aytekin <tevfik.ayte...@gmail.com> wrote: > Hi Sean, > Isn't boolean preferences is supported in the context of memory-based > recommendation algorithms in Mahout? > Are there matrix factorization algorithms in Mahout which can work > with this kind of data (that is, the kind of data which consists of > users and the movies they have seen). > > > > > On Mon, May 6, 2013 at 10:34 PM, Sean Owen <sro...@gmail.com> wrote: >> Yes, it goes by the name 'boolean prefs' in the project since target >> variables don't have values -- they just exist or don't. >> So, yes it's certainly supported but the question here is how to >> evaluate the output. >> >> On Mon, May 6, 2013 at 8:29 PM, Tevfik Aytekin <tevfik.ayte...@gmail.com> >> wrote: >>> This problem is called one-class classification problem. In the domain >>> of collaborative filtering it is called one-class collaborative >>> filtering (since what you have are only positive preferences). You may >>> search the web with these key words to find papers providing >>> solutions. I'm not sure whether Mahout has algorithms for one-class >>> collaborative filtering. >>> >>> On Mon, May 6, 2013 at 1:42 PM, Sean Owen <sro...@gmail.com> wrote: >>>> ALS-WR weights the error on each term differently, so the average >>>> error doesn't really have meaning here, even if you are comparing the >>>> difference with "1". I think you will need to fall back to mean >>>> average precision or something. >>>> >>>> On Mon, May 6, 2013 at 11:24 AM, William <icswilliam2...@gmail.com> wrote: >>>>> Sean Owen <srowen <at> gmail.com> writes: >>>>> >>>>>> >>>>>> If you have no ratings, how are you using RMSE? this typically >>>>>> measures error in reconstructing ratings. >>>>>> I think you are probably measuring something meaningless. >>>>>> >>>>> >>>>> >>>>> I suppose the rate of seen movies are 1. Is it right? >>>>> If I use Collaborative Filtering with ALS-WR to get some recommendations, >>>>> I >>>>> must have a real rating-matrix? >>>>> >>>>> >>>>>
