Description
This example shows: how to set a bitmap in a GRIB message
Source code
grib_set_bitmap.f90
! Copyright 2005-2015 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. ! ! ! ! Description: how to set a bitmap in a GRIB message ! ! ! program set_bitmap use eccodes implicit none integer :: infile,outfile integer :: igrib, iret integer :: numberOfValues real, dimension(:), allocatable :: values real :: missingValue logical :: grib1Example grib1Example=.true. if (grib1Example) then ! GRIB 1 example call codes_open_file(infile,'../../data/regular_latlon_surface.grib1','r') else ! GRIB 2 example call codes_open_file(infile,'../../data/regular_latlon_surface.grib2','r') end if call codes_open_file(outfile,'out.bmp.grib','w') ! A new grib message is loaded from file ! igrib is the grib id to be used in subsequent calls call codes_grib_new_from_file(infile,igrib) ! 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 in a way that it cannot be confused ! with a valid field value missingValue=9999 call codes_set(igrib, 'missingValue',missingValue) write(*,*) 'missingValue=',missingValue ! get the size of the values array call codes_get_size(igrib,'values',numberOfValues) write(*,*) 'numberOfValues=',numberOfValues allocate(values(numberOfValues), stat=iret) ! get data values call codes_get(igrib,'values',values) ! enable bitmap call codes_set(igrib, 'bitmapPresent', 1) ! some values are missing values(1:10) = missingValue ! set the values (the bitmap will be automatically built) call codes_set(igrib,'values', values) ! write modified message to a file call codes_write(igrib,outfile) ! free memory call codes_release(igrib) call codes_close_file(infile) call codes_close_file(outfile) deallocate(values) end program set_bitmap
grib_set_bitmap.py
# Copyright 2005-2015 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 traceback import sys from eccodes import * INPUT = '../../data/regular_latlon_surface.grib1' OUTPUT = 'out.bmp.grib' MISSING = 9999 VERBOSE = 1 # verbose error reporting def example(): fin = open(INPUT) fout = open(OUTPUT, 'w') gid = codes_grib_new_from_file(fin) codes_set(gid, 'missingValue', MISSING) values = codes_get_values(gid) codes_set(gid, 'bitmapPresent', 1) # Change some data values to be missing num_missing = 0 for i in range(100): 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(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, err: if VERBOSE: traceback.print_exc(file=sys.stderr) else: print >> sys.stderr, err.msg return 1 if __name__ == "__main__": sys.exit(main())
grib_set_bitmap.c
/* * Copyright 2005-2015 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. */ /* * C Implementation: grib_set_bitmap * * Description: how to set a bitmap in a GRIB message * * */ #include <stdio.h> #include <stdlib.h> #include "eccodes.h" int main(int argc, char** argv) { int err = 0; size_t size=0; FILE* in = NULL; char* infile = "../../data/regular_latlon_surface.grib1"; FILE* out = NULL; char* outfile = "out.grib1"; codes_handle *h = NULL; const void* buffer = NULL; size_t values_len; double* values; double missing=9999; int i=0; in = fopen(infile,"r"); if(!in) { printf("ERROR: unable to open input file %s\n",infile); return 1; } out = fopen(outfile,"w"); if(!out) { printf("ERROR: unable to open output file %s\n",outfile); fclose(in); return 1; } h = codes_handle_new_from_file(0, in, PRODUCT_GRIB, &err); if (h == NULL) { printf("Error: unable to create handle from file %s\n",infile); } CODES_CHECK(codes_set_double(h,"missingValue",missing),0); /* get the size of the values array*/ CODES_CHECK(codes_get_size(h,"values",&values_len),0); values = (double*)malloc(values_len*sizeof(double)); /* get data values*/ CODES_CHECK(codes_get_double_array(h,"values",values,&values_len),0); CODES_CHECK(codes_set_long(h,"bitmapPresent",1),0); for(i = 0; i < 10; i++) values[i]=missing; CODES_CHECK(codes_set_double_array(h,"values",values,values_len),0); /* get the coded message in a buffer */ CODES_CHECK(codes_get_message(h,&buffer,&size),0); /* write the buffer in a file*/ if(fwrite(buffer,1,size,out) != size) { perror(outfile); exit(1); } /* delete handle */ codes_handle_delete(h); fclose(in); fclose(out); return 0; }