lenskit.metrics.reranking
=========================

.. py:module:: lenskit.metrics.reranking

.. autoapi-nested-parse::

   LensKit reranking metrics.



Functions
---------

.. autoapisummary::

   lenskit.metrics.reranking.least_item_promoted
   lenskit.metrics.reranking.rank_biased_overlap



Package Contents
----------------

.. py:function:: least_item_promoted(reference, reranked, n = 10)

   Compute the Least Item Promoted (LIP) metric.

   This metric identifies the item in the top-k reranked list that had the
   highest (worst) rank in the reference, and returns how many positions
   it was promoted from beyond k.

   :param reference: The original/base ranking.
   :param reranked: The reranked list.
   :param n: The depth to evaluate (default 10).

   :returns: The rank distance of the least-promoted item, or NaN if the base
             ranking is empty.

   :Stability: Experimental


.. py:function:: rank_biased_overlap(reference, reranked, weight = None, n = 10)

   Computes the Rank Biased Overlap (RBO) between two item rankings.
   RBO is defined by :cite:t:`webberSimilarityMeasureIndefinite2010`.

   :param reference: The first item list to compare.
   :param reranked: The second item list to compare.
   :param weight: The rank weighting to use. If None, defaults to GeometricRankWeight(0.85).
   :param n: The depth to which to compute the overlap (default 10).

   :returns: The RBO score between 0 and 1.

   :Stability: Experimental