I'm not trying to distinguish them. That is the "find the Netflix user" paper :)
I just want to understand the cross-recommender concept, that's all. Yes, this sample is too small to impute "enthusiasm"- the numbers are recommendation values. (If the rest of you want to follow along: http://www.slideshare.net/tdunning/intelligent-search , slides 35-36) On Mon, Nov 22, 2010 at 11:50 PM, Sean Owen <[email protected]> wrote: > (PS I don't think that link from Ted is publicly visible but try > http://www.slideshare.net/tdunning ) > > Maybe I'm walking into half of a another conversation but what's the > question or goal here? > > I don't think the matrix product contains quite what you're saying. > For example U1 records only 2 ratings but has some "enthusiasm" on 3 > separate days in the matrix product. The product is mashing together > item-day associations from all users and applying them to each user. > > Conceptually user-item-day is the 3-dimensional matrix that it sounds > like, if you want to distinguish associations from different users to > different items on different days. > > > On Tue, Nov 23, 2010 at 7:24 AM, Lance Norskog <[email protected]> wrote: >> The GroupLens dataset has User, Item, Rating and Timestamp. >> We will use the rating of 1-5 as-is, but will reduce the timestamp >> field to day of the week. >> The lack of a rating defaults two 3 (neutral). There are 5 ratings >> total in the sample: >> >> U1, I1, 2, ? >> U1, I3, 4, ? >> U2, I1, 4, ? >> U2, I2, 5, T >> U2, I3, 3, ? >> >> (We'll get to the question marks later.) >> Now, make two matrices, User v.s. Item and Item v.s. Day of the Week. >> User v.s. Item contains ratings, and Item v.s. Day of the Week >> contains the number of rating records for that item on that day of the >> week: ratings only cover Sunday, Monday and Tuesday. >> >> Formatting tables in kerned fonts just plain doesn't work, thus the >> alternate format. >> >> 2 Users v.s. 3 Items: >> I1,I2,I3 >> { >> U1 {2,3,4} >> U2 {4,5,3} >> } >> >> 3 Items v.s. 7 Days of the Week >> S,M,T,W,T,F,S >> { >> I1 {1,0,1,0,0,0,0} >> I2 {0,0,1,0,0,0,0} >> I3 {0,1,1,0,0,0,0} >> } >> >> Now, multiply these two matrices. The product is 2 Users v.s. 7 Days >> of the Week: >> S,M,T,W,T,F,S >> { >> U1 {2,4,9,0,0,0,0} >> U2 {4,3,12,0,0,0,0} >> } >> >> This matrix carries the total amount of enthusiasm for each user on >> each day. To get the average enthusiasm of each user, divide each row >> by the total number of ratings per day: >> S,M,T,W,T,F,S >> { >> U1 {2,4,3,0,0,0,0} >> U2 {4,3,4,0,0,0,0} >> } >> >> Did I get this right, Ted? >> >> BTW, where are your slides for this topic? I've seen them a couple of >> times in presentations (live and on Fora.tv), but can't find them. >> >> -- >> Lance Norskog >> [email protected] >> > -- Lance Norskog [email protected]
