Preface

The path to here, for me (Sean), began in 2005. A friend was starting a company that would lean heavily on collaborative filtering. There were mature, open source packages for this purpose at the time, but they seemed in some ways too elaborate for simple use cases, and in other ways they seemed built for research purposes. For better or worse, I instead prototyped a simple recommender for my friend’s startup, from scratch. The startup, unfortunately, cancelled itself. Nevertheless, I couldn’t bring myself to delete the prototype. It was certainly interesting, so I cleaned and documented it and released it as an open source project called Taste.

Nothing happened for a year. In my spare time, I added pieces and fixed problems, and then a user or two popped up with bugs and patches—and a few more, and then several more. By 2008, there was a small but unmistakable user base out there. And the Apache Lucene folks who had just spun off machine-learning-related efforts into Apache Mahout suggested we merge. This book project began in late 2009. I find myself surprised and pleased to still be rolling along with this growing snowball of a project in 2011 as it’s beginning to be used by large companies in production.