Ranking Algorithms#
LensKit provides several ranking components that rank items.
The usual design for a ranker is to take as input a list of items named items,
usually with scores (typically the output of a scoring model),
and possibly the query, and return an ordered item list. Rankers can also take
ranked inputs for re-ranking. By convention, they are named XYZRanker.
Top-N Ranking#
Classic top-N ranking is provided by lenskit.basic.TopNRanker. The
standard pipelines configured by RecPipelineBuilder
use this ranker by default.
Stochastic Ranking#
lenskit.basic.SoftmaxRankercomputes a randomized Plackett-Luce ranking, where each item is selected with probability proportional to its score.lenskit.basic.RandomSelectorselects items uniformly at random.