eccodes/examples/python/grib_set_bitmap.py

73 lines
1.9 KiB
Python

# (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.
import sys
import traceback
from eccodes import *
INPUT = "../../data/regular_latlon_surface.grib1"
OUTPUT = "out.set_bitmap_p.grib"
MISSING = 1.0e36
VERBOSE = 1 # verbose error reporting
def example():
fin = open(INPUT, "rb")
fout = open(OUTPUT, "wb")
gid = codes_grib_new_from_file(fin)
# The missingValue is not coded in the message.
# It is a value we define as a placeholder for a missing value
# at a point in the grid.
# It should be chosen so that it cannot be confused
# with a valid field value
codes_set(gid, "missingValue", MISSING)
values = codes_get_values(gid)
# Enable bitmap
codes_set(gid, "bitmapPresent", 1)
# Change some data values to be missing
num_missing = 0
for i in range(100):
# Set every other value to a missing value
if i % 2 == 0:
values[i] = MISSING
num_missing += 1
codes_set_values(gid, values)
# Check counts of missing and non-missing values
num_data = codes_get(gid, "numberOfDataPoints", int)
assert num_data == len(values)
assert codes_get(gid, "numberOfCodedValues", int) == num_data - num_missing
assert codes_get(gid, "numberOfMissing", int) == num_missing
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:
print(err.msg, file=sys.stderr)
return 1
if __name__ == "__main__":
sys.exit(main())