Affects Version/s: None
Fix Version/s: None
Currently mllib.recommendation.MatrixFactorizationModel has methods recommendProducts/recommendUsers for recommending top K to a given user / item, as well as recommendProductsForUsers/recommendUsersForProducts to recommend top K across all users/items.
SPARK-10802 is for adding the ability to do recommendProductsForUsers for a subset of users (or vice versa).
Look at exposing or porting (as appropriate) these methods to ALS in ML.
Investigate if efficiency can be improved at the same time (see