eccodes/examples/C/grib_set_data.c

90 lines
2.7 KiB
C

/*
* (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.
*/
/*
* C Implementation: grib_set_data
*
* Description: set the data contained in a GRIB file.
* In this example no missing values are present
* If there are missing values, refer to: grib_set_bitmap
*
*/
#include <stdio.h>
#include <stdlib.h>
#include "eccodes.h"
static void usage(const char* prog)
{
printf("usage: %s out.grib\n", prog);
exit(1);
}
int main(int argc, char** argv)
{
int i;
double* values = NULL;
size_t values_len = 0;
/* Note: the full name of the sample file is "regular_ll_pl_grib1.tmpl" */
/* Sample files are stored in the samples directory (use codes_info to */
/* see where that is). The default sample path can be changed by */
/* setting the environment variable ECCODES_SAMPLES_PATH */
const char* sample_filename = "regular_ll_pl_grib1";
/* here is how you can get the samples path */
const char* samples_path = codes_samples_path(NULL);
codes_handle* h = NULL;
double d, e;
long count;
if (argc != 2) usage(argv[0]);
/* create new handle from message in sample file */
printf("Using samples path: %s\n", samples_path);
h = codes_grib_handle_new_from_samples(0, sample_filename);
if (h == NULL) {
fprintf(stderr, "Error: unable to create handle from sample file %s\n", sample_filename);
return 1;
}
/* here we're changing the data values only, so the number of values */
/* will be the same as the sample GRIB. */
/* But if your data array has a different size, then specify the grid geometry */
/* (e.g. keys Ni, Nj etc) and set the correct number of data values */
CODES_CHECK(codes_get_size(h, "values", &values_len), 0);
values = (double*)malloc(values_len * sizeof(double));
d = 10e-8;
e = d;
count = 1;
for (i = 0; i < values_len; i++) {
if (count > 100) {
e *= 10;
count = 1;
}
values[i] = d;
/*printf("%g \n",values[i]);*/
d += e;
count++;
}
CODES_CHECK(codes_set_long(h, "bitsPerValue", 16), 0);
/* set data values */
CODES_CHECK(codes_set_double_array(h, "values", values, values_len), 0);
CODES_CHECK(codes_write_message(h, argv[1], "w"), 0);
free(values);
codes_handle_delete(h);
return 0;
}