lenskit.splitting.LastFrac
==========================

.. py:class:: lenskit.splitting.LastFrac(frac, field = 'timestamp')
   :canonical: lenskit.splitting._holdout.LastFrac

   Bases: :py:obj:`HoldoutMethod`


   Select a fraction of test rows per user/item.

   :Stability: Caller

   :param frac: the fraction of items to select for testing.
   :type frac: double


   .. py:attribute:: fraction
      :type:  float


   .. py:attribute:: field
      :type:  str


   .. py:method:: __call__(items)

      Subset an item list (in the uncommon case of item-based holdouts, the
      item list actually holds user IDs).

      :param udf: The item list from which holdout items should be selected.

      :returns: The list of test items.