Shuo Xiang created SPARK-2085: --------------------------------- Summary: Apply user-specific regularization instead of uniform regularization in Alternating Least Squares (ALS) Key: SPARK-2085 URL: https://issues.apache.org/jira/browse/SPARK-2085 Project: Spark Issue Type: Improvement Components: MLlib Affects Versions: 1.0.0 Reporter: Shuo Xiang Priority: Minor
The current implementation of ALS takes a single regularization parameter and apply it on both of the user factors and the product factors. This kind of regularization can be less effective while users number is significantly larger than the number of products (and vice versa). For example, if we have 10M users and 1K product, regularization on user factors will dominate. Following the discussion in [this thread](http://apache-spark-user-list.1001560.n3.nabble.com/possible-bug-in-Spark-s-ALS-implementation-tt2567.html#a2704), the implementation in this PR will regularize each factor vector by #ratings * lambda. -- This message was sent by Atlassian JIRA (v6.2#6252)