mahout - Duplicate records in data for Myrrix?

Question

Can someone help me identify how Myrrix handles if there are duplicated records of in the input data? What would be the result in the case of implicit as well as explicit feedback data? What if explicit feedback duplicated records have different ratings?

Answer 1

Data is always additive. So "user,item,X" and "user,item,Y" is (essentially) like "user,item,X+Y". Input without a value are considered to have value 1.