nearest_gridpoint_info

nearest_gridpoint_info(fs, lat, lon[, mode])
nearest_gridpoint_info(fs, location[, mode])

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

Parameters

  • fs (Fieldset) – input fieldset

  • lat (number) – target latitude

  • lon (number) – target longitude

  • location (list) – single target location defined as a list of [lat, lon]

  • mode (str) – specifies the way missing values are handled. The only allowed value is “valid”.

Return type

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:

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 nearest_gridpoint(), surrounding_points_indexes() and interpolate().

Notebooks using metview.nearest_gridpoint_info

thumbnail

Regridding GRIB data and extracting values at scattered locations