lenskit.metrics.ranking.Precision
=================================

.. py:class:: lenskit.metrics.ranking.Precision(n = None, *, k = None)
   :canonical: lenskit.metrics.ranking._pr.Precision

   Bases: :py:obj:`lenskit.metrics.ranking._base.ListMetric`, :py:obj:`lenskit.metrics.ranking._base.RankingMetricBase`


   Compute recommendation precision.  This is computed as:

   .. math::
       \frac{|L \cap I_u^{\mathrm{test}}|}{|L|}

   In the uncommon case that ``k`` is specified and ``len(recs) < k``, this metric uses
   ``len(recs)`` as the denominator.

   :Stability: Caller


   .. py:property:: label

      The metric's default label in output.
      The base implementation returns the class name by default.


   .. py:method:: measure_list(recs, test)

      Compute measurements for a single list.

      :returns:

                - A float for simple metrics
                - Intermediate data for decomposed metrics
                - A dict mapping metric names to values for multi-metric classes