eccodes/examples/python/grib_set_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_set_keys
#
# Description: how to set key values in GRIB messages
#

import sys
import traceback
from collections import OrderedDict
from datetime import date

from eccodes import *

INPUT = "../../data/regular_latlon_surface_constant.grib1"
OUTPUT = "out.set.grib"
VERBOSE = 1  # verbose error reporting


def example():
    fin = open(INPUT, "rb")
    fout = open(OUTPUT, "wb")
    gid = codes_grib_new_from_file(fin)

    dt = date.today()
    today = "%d%02d%02d" % (dt.year, dt.month, dt.day)
    codes_set(gid, "dataDate", int(today))
    codes_set(gid, "centre", 80)

    centreIntVal = codes_get_array(gid, "centre", int)
    centreStrVal = codes_get_array(gid, "centre", str)
    dateStrVal = codes_get_array(gid, "dataDate", str)
    assert centreIntVal[0] == 80
    assert centreStrVal[0] == "cnmc"
    assert dateStrVal[0] == today
    print("get centre as an integer - centre = %d" % centreIntVal[0])
    print("get centre as a string - centre = %s" % centreStrVal[0])
    print("get date as a string - date = %s" % dateStrVal[0])

    # Now do the same but using set_key_vals, setting keys all at once
    print("set keys using one long comma-separated string...")
    codes_set_key_vals(gid, "level=1,centre=98")
    assert codes_get(gid, "centre", str) == "ecmf"
    assert codes_get(gid, "level", int) == 1

    print("set keys using a list of strings...")
    codes_set_key_vals(gid, ["level=2", "centre=kwbc"])
    assert codes_get(gid, "centre", int) == 7
    assert codes_get(gid, "level", int) == 2

    print("set keys using a dictionary (order not as specified!)...")
    codes_set_key_vals(gid, {"level": 3, "centre": 84})
    assert codes_get(gid, "centre", str) == "lfpw"
    assert codes_get(gid, "level", int) == 3

    print("set keys using an ordered dictionary...")
    codes_set_key_vals(gid, OrderedDict([("level", 3), ("centre", 84)]))
    assert codes_get(gid, "centre", str) == "lfpw"
    assert codes_get(gid, "level", int) == 3

    codes_gts_header(True)
    codes_gts_header(False)

    codes_write(gid, fout)
    codes_release(gid)
    fin.close()
    fout.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())