pl_to_pl
=============

.. py:function:: pl_to_pl(fs, pressures, [method])

   *New in Metview version 5.17.0*.
   
   Interpolates ``fs`` from pressure levels onto a set of pressure levels defined by ``pressures``. 
   
   :param fs: fieldset to be interpolated (must contain pressure levels!). Does not have to be sorted by level.
   :type fs: :class:`Fieldset`
   :param pressures: target pressure levels in hPa. Does not have to be sorted. 
   :type pressures: list or ndarray
   :param str method: specifies the interpolation method. The possible values are "linear" and "log". If it is not specified linear interpolation is used.
   :rtype: :class:`Fieldset`
  
   The input data (``fs``) must contain one field per pressure level only. It means that e.g. data containing multiple timesteps cannot be used as an input.
   
   At gridpoints where the interpolation is not possible a missing value is returned. It happens where the target pressure is outside the pressure level range in ``fs``. 
    
   :Example:
   
      This code illustrates how to use :func:`pl_to_pl` with data retrieved from MARS:

      .. code-block:: python

         import metview as mv

         # get pressure level fields from MARS
         f = mv.retrieve(type="an",
            date=-1, 
            time=12, 
            levelist=[1000, 925, 850, 700],
            param="t", 
            grid=[1,1])

         # interpolate onto a list of pressure levels
         p_levels = [965, 850, 815, 723.5]
         r = mv.pl_to_pl(f, p_levels)


.. mv-minigallery:: pl_to_pl