Thanks to you both, Peng/Pat. Sure I can map them out. Not a problem. The issue is the output returns all the matches from within the same set. So while I am only interested in the inter-set comparison (A vs B), the output I get has only intra-set comparisons (A vs A and B vs B). Upon filtering, there is no entry left for the A vs B.
Sent from my iPad > On Jul 10, 2014, at 7:44 PM, Pat Ferrel <[email protected]> wrote: > > Right, as Peng says IDs are the row and column numbers in the input matrix > 0..n, 0..m You assign them by incrementing for each unique application > specific id. Use a hashmap or databased to maintain your own mapping > dictionary from your IDs below into and out of Mahout IDs. The matrix is > users = rows, items = columns. > > So for a particular item in the A set you want to recommend something similar > from the B set. You do this by creating an input set that meats the above > needs for IDs, the preference can be your rating number but often translating > that into a boolean is as good if not better. Either way is OK but no 0 or > below number for preference. The ID will be for all users and for all books > from either set. > > Then you want to ask the ItemBasesRecommender for > > List<RecommendedItem> mostSimilarItems(long itemID, int howMany) throws > TasteException; > > Filter out any items you don’t want from the list and return the ones with > the highest strength. Notice the itemID is the Mahout column number for the > item in question. So if You were on an Amazon page for a book it would be the > Mahout ID for the book the user was looking at. The results will be from A > and B so filter the ones you don’t want. > > > > > On Jul 10, 2014, at 7:11 PM, Peng Zhang <[email protected]> wrote: > > Jiten, > > User and Book ids should be 0,1,2 etc. Plz don't use negative integers. > > Since I don't understand +ve/-ve you mentioned, but if you know which books > belong to class A/B, you can filter the output correlation matrix yourself to > get what you want. > > Peng Zhang > > -- > Sent from my iPhone > >> On Jul 11, 2014, at 9:49 AM, "Jiten Gore" <[email protected]> wrote: >> >> Thanks for your reply, Pat. Here's an illustration: >> >> The input set looks like this: >> User Book Preference >> 1 10 7 >> 2 10 4 >> 3 10 5 >> 1 15 3 >> 2 15 8 >> 3 15 4 >> 1 20 9 >> 2 20 2 >> 3 20 3 >> 1 -1 8 >> 2 -1 8 >> 3 -1 2 >> 1 -2 5 >> 2 -2 6 >> 3 -2 4 >> 1 -3 7 >> 2 -3 5 >> 3 -4 3 >> ... >> >> For this set for the books (+ve set) I am interested in only the >> recommendations for the Books (-ve set) >> >> The desired output (the values are made up): >> Book1 Book2 ρ-value >> 10 -2 0.75 >> 10 -3 0.66 >> 10 -1 0.41 >> 15 -1 0.80 >> 15 -2 0.55 >> 15 -3 0.21 >> 20 -2 0.91 >> 20 -1 0.65 >> 20 -3 0.47 >> >> Thus, I would *not* like to see the ones like these two: >> 10 20 0.61 >> -1 -2 0.73 >> >> Does this help in clarifying? And yes I am interested in Pearson correlation >> and I am using Hadoop. >> >> Best, >> Jiten >> >> -----Original Message----- >> From: Pat Ferrel [mailto:[email protected]] >> Sent: Thursday, July 10, 2014 1:42 PM >> To: [email protected] >> Subject: Re: Recommender question >> >> Can you rephrase this "I would like to see recommendations for A class books >> only out of those from class B." >> >> >> On Jul 10, 2014, at 11:25 AM, Jiten Gore <[email protected]> wrote: >> >> Dear Mahout community, >> >> I am running an item based recommender on Mahout and using the Amazon >> paradigm, consider that there are books - two classes of books, one (A) >> coded with +ve ID values and the other (B) with -ve values for ID. >> >> I would like to see recommendations for A class books only out of those from >> class B. The user ratings structure is the same for both classes. >> >> I will appreciate any pointers you might have. >> >> Best, >> Jiten >> >> Sent from my iPhone > >
