BPR learning example about javafm

[saulvargas]

Hi @parklize

First of all, my apologies for answering so late, I messes my mail filters and did not get any notifications from Github for a long time. I understand this may be too late, but here is my answer.

The current implementation of BPR-FM is quite hackish, and it only covers a pure collaborative filtering scenario (no context, no user or item-side information). Please take a look at RankSys, in particular the code here https://github.com/RankSys/RankSys/blob/master/RankSys-fm/src/main/java/org/ranksys/fm/data/BPRPreferenceFMData.java and here https://github.com/RankSys/RankSys/blob/master/RankSys-examples/src/main/java/es/uam/eps/ir/ranksys/examples/RecommenderExample.java to know how I am actually using it.