nearest_gridpoint_info.rst

nearest_gridpoint_info

.. py:function:: nearest_gridpoint_info(fs, lat, lon, [mode])

.. py:function:: nearest_gridpoint_info(fs, location, [mode])
   :noindex:


   Returns the value and location of the nearest grid point to a given location in each field in ``fs``.

   :param fs: input fieldset
   :type fs: :class:`Fieldset`
   :param lat: target latitude
   :type lat: number
   :param lon: target longitude
   :type lon: number
   :param location: single target location defined as a list of [lat, lon]
   :type location: list
   :param str mode: specifies the way missing values are handled. The only allowed value is "valid".
   :rtype: list of dict

   The return value is a **list** containing the following values for each field:

   If the nearest gridpoint value is non missing a dictionary is returned with these members:

   * latitude: latitude of the nearest gridpoint
   * longitude: longitude of the nearest gridpoint
   * index: index of nearest gridpoint within the field
   * distance: distance between the nearest gridpoint and the specified location in km
   * value: value at the nearest gridpoint

   If the nearest gridpoint has missing value the return value depends on ``mode``:

      * if ``mode`` is not specified None is returned
      * if ``mode`` is "valid" the dictionary for the nearest valid point from the surrounding gridpoints is returned. If all the surrounding points are missing None is returned

   This example:

   .. code-block:: python

      import metview as mv

      # read grib with 2 fields on a 1.5x1.5 degree grid
      f = mv.read("my_data.grib")

      # get nearest gridpoint info
      info = mv.nearest_gridpoint_info(f, 47, 19)
      print(info)

   generates the following output::

      [{'latitude': 46.5, 'longitude': 19.5,
        'index': 6973.0, 'distance': 67.3506,
        'value': 291.144},
       {'latitude': 46.5, 'longitude': 19.5,
        'index': 6973.0, 'distance': 67.3506,
        'value': 294.011'}]


   .. note::

      See also :func:`nearest_gridpoint`, :func:`surrounding_points_indexes` and :func:`interpolate`.

.. mv-minigallery:: nearest_gridpoint_info