lenskit.splitting.LastN
=======================

.. py:class:: lenskit.splitting.LastN(n, field = 'timestamp')
   :canonical: lenskit.splitting._holdout.LastN

   Bases: :py:obj:`HoldoutMethod`


   Select a fixed number of test rows per user/item, based on ordering by a
   field.

   :Stability: Caller

   :param n: The number of test items to select.
   :param field: The field to order by.


   .. py:attribute:: n
      :type:  int


   .. 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.