I will think further but in the current implicit formulation with
confidence, looks like I am factorizing a 0/1 matrix with weights 1 +
alpha*rating for observed (1) values and 1 for unobserved (0) values. It's
a bit different from LSA model.
>> On Sun, Jul 26, 2015 at 6:45 AM, Debasish Das <debasish.das83@gmail.com>
>> wrote:
>> > Hi,
>> >
>> > Implicit factorization is important for us since it drives
>> recommendation
>> > when modeling user click/noclick and also topic modeling to handle 0
>> counts
>> > in document x word matrices through NMF and Sparse Coding.
>> >
>> > I am a bit confused on this code:
>> >
>> > val c1 = alpha * math.abs(rating)
>> > if (rating > 0) ls.add(srcFactor, (c1 + 1.0)/c1, c1)
>> >
>> > When the alpha = 1.0 (high confidence) and rating is > 0 (true for word
>> > counts), why this formula does not become same as explicit formula:
>> >
>> > ls.add(srcFactor, rating, 1.0)
>> >
>> > For modeling document, I believe implicit Y'Y needs to stay but we need
>> > explicit ls.add(srcFactor, rating, 1.0)
>> >
>> > I am understanding confidence code further. Please let me know if the
>> idea
>> > of mapping implicit to handle 0 counts in document word matrix makes
>> sense.
>> >
>> > Thanks.
>> > Deb
>> >
>>
>
>
