eccodes/examples/python/grib_get_keys.py

# (C) Copyright 2005- ECMWF.
#
# This software is licensed under the terms of the Apache Licence Version 2.0
# which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
#
# In applying this licence, ECMWF does not waive the privileges and immunities
# granted to it by virtue of its status as an intergovernmental organisation
# nor does it submit to any jurisdiction.

# Python implementation: grib_get_keys
#
# Description: how to get values using keys from GRIB messages
#

import sys
import traceback

from eccodes import *

INPUT = "../../data/reduced_latlon_surface.grib1"
VERBOSE = 1  # verbose error reporting


def example():
    f = open(INPUT, "rb")

    keys = [
        "Ni",
        "Nj",
        "latitudeOfFirstGridPointInDegrees",
        "longitudeOfFirstGridPointInDegrees",
        "latitudeOfLastGridPointInDegrees",
        "longitudeOfLastGridPointInDegrees",
    ]

    while 1:
        gid = codes_grib_new_from_file(f)
        if gid is None:
            break

        for key in keys:
            try:
                print("  %s: %s" % (key, codes_get(gid, key)))
            except KeyValueNotFoundError as err:
                # Full list of exceptions here:
                #   https://confluence.ecmwf.int/display/ECC/Python+exception+classes
                print('  Key="%s" was not found: %s' % (key, err.msg))
            except CodesInternalError as err:
                print('Error with key="%s" : %s' % (key, err.msg))

        print(
            "There are %d values, average is %f, min is %f, max is %f"
            % (
                codes_get_size(gid, "values"),
                codes_get(gid, "average"),
                codes_get(gid, "min"),
                codes_get(gid, "max"),
            )
        )

        codes_release(gid)

    f.close()


def main():
    try:
        example()
    except CodesInternalError as err:
        if VERBOSE:
            traceback.print_exc(file=sys.stderr)
        else:
            sys.stderr.write(err.msg + "\n")

        return 1


if __name__ == "__main__":
    sys.exit(main())