/usr/share/doc/libeccodes-dev/examples/C/grib_iterator_bitmap.c is in libeccodes-dev 2.6.0-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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* Copyright 2005-2017 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 use an iterator on lat/lon/values and query the bitmap
* for missing values
* (rather than compare each value with the missingValue key)
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include "eccodes.h"
static void usage(const char* prog)
{
printf("Usage: %s grib_file\n",prog);
exit(1);
}
int main(int argc, char** argv)
{
FILE* in = NULL;
int err = 0;
double lat,lon,value;
int n=0;
size_t bmp_len = 0, values_len = 0;
char* filename = NULL;
long bitmapPresent = 0;
long *bitmap = NULL;
double *values = NULL;
codes_handle *h = NULL;
codes_iterator* iter=NULL;
if (argc != 2) usage(argv[0]);
filename=argv[1];
in = fopen(filename,"r");
if(!in) {
fprintf(stderr, "ERROR: unable to open file %s\n",filename);
return 1;
}
while ((h = codes_handle_new_from_file(0, in, PRODUCT_GRIB, &err)) != NULL )
{
if (err != CODES_SUCCESS) CODES_CHECK(err,0);
CODES_CHECK(codes_get_long(h,"bitmapPresent",&bitmapPresent),0);
if (bitmapPresent)
{
CODES_CHECK(codes_get_size(h,"bitmap",&bmp_len),0);
bitmap = (long*)malloc(bmp_len*sizeof(long));
CODES_CHECK(codes_get_long_array(h,"bitmap",bitmap,&bmp_len),0);
printf("Bitmap is present. Num = %lu\n", bmp_len);
}
/* Sanity check. Number of values must match number in bitmap */
CODES_CHECK(codes_get_size(h,"values",&values_len),0);
values = (double*)malloc(values_len*sizeof(double));
CODES_CHECK(codes_get_double_array(h,"values",values,&values_len),0);
if (bitmapPresent) {
assert(values_len==bmp_len);
}
/* A new iterator on lat/lon/values is created from the message handle h */
iter=codes_grib_iterator_new(h,0,&err);
if (err != CODES_SUCCESS) CODES_CHECK(err,0);
n = 0;
/* Loop on all the lat/lon/values. Only print non-missing values */
while(codes_grib_iterator_next(iter,&lat,&lon,&value))
{
/* Consult bitmap to see if the n'th value is missing */
int is_missing_val = (bitmapPresent && bitmap[n] == 0);
if (!is_missing_val) {
printf("- %d - lat=%f lon=%f value=%f\n",n,lat,lon,value);
}
n++;
}
/* Check number of elements in iterator matches value count */
assert(n == values_len);
codes_grib_iterator_delete(iter);
codes_handle_delete(h);
}
fclose(in);
return 0;
}
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