lenskit.metrics.basic.UniqueItemCount
=====================================

.. py:class:: lenskit.metrics.basic.UniqueItemCount
   

   Bases: :py:obj:`lenskit.metrics.Metric`\ [\ :py:obj:`lenskit.data.types.IDSequence`\ , :py:obj:`int`\ ]


   Count the number of unique items in the recommendation lists.

   :Stability: Caller


   .. 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



   .. py:method:: create_accumulator()

      Creaet an accumulator to aggregate per-list measurements into summary
      metrics.

      Each result from :meth:`measure_list` is passed to
      :meth:`Accumulator.add`.