Recommendation Systems (2): Collaborative Filtering and Matrix Factorization

Thu, 04 Dec 2025 09:00:00 +0000

You finish The Shawshank Redemption and want something with the same feeling. A genre filter would surface every prison drama ever made, most of them awful. Collaborative filtering takes a different route: it never looks at the movie itself. It looks at people who watched what you watched and asks what else they loved.

That single idea — let the crowd’s behaviour speak — powers Amazon, YouTube, Spotify and every modern feed. This article unpacks the algorithms behind it, from the neighbourhood methods of the 1990s to the matrix-factorization models that won the Netflix Prize.

Matrix Factorization on Chen Kai Blog

Recommendation Systems (2): Collaborative Filtering and Matrix Factorization