Ranking Methods

The lenskit.algorithms.ranking module contains various ranking methods: algorithms that can use scores to produce ranks. This includes primary rankers, like TopN, and some re-rankers as well.

Top-N Recommender

The TopN class implements a standard top-N recommender that wraps a Predictor and CandidateSelector and returns the top N candidate items by predicted rating. It is the type of recommender returned by Recommender.adapt() if the provided algorithm is not a recommender.

Stochastic Recommenders

The PlackettLuce class implements a stochastic recommender. The underlying relevance scores are kept the same, but the rankings are sampled from a Plackett-Luce distribution instead using a deterministic top-N policy.