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/*
* (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_iterator
*
* Description: how to use an iterator on lat/lon/values for GRIB messages
*
*/
#include <stdio.h>
#include <stdlib.h>
#include "grib_api.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;
double missingValue = 1e+20; /* A value out of range */
int n = 0;
long bitmapPresent = 0;
char* filename = NULL;
/* Message handle. Required in all the ecCodes calls acting on a message.*/
grib_handle* h = NULL;
/* Iterator on lat/lon/values.*/
grib_iterator* iter = NULL;
if (argc != 2) usage(argv[0]);
filename = argv[1];
in = fopen(filename, "rb");
if (!in) {
fprintf(stderr, "Error: unable to open file %s\n", filename);
return 1;
}
/* Loop on all the messages in a file.*/
while ((h = grib_handle_new_from_file(0, in, &err)) != NULL) {
/* Check of errors after reading a message. */
if (err != GRIB_SUCCESS) GRIB_CHECK(err, 0);
/* Check if a bitmap applies */
GRIB_CHECK(grib_get_long(h, "bitmapPresent", &bitmapPresent), 0);
if (bitmapPresent) {
/* Set the double representing the missing value in the field. */
/* Choose a missingValue that does not correspond to any real value in the data array */
GRIB_CHECK(grib_set_double(h, "missingValue", missingValue), 0);
}
/* A new iterator on lat/lon/values is created from the message handle h. */
iter = grib_iterator_new(h, 0, &err);
if (err != GRIB_SUCCESS) GRIB_CHECK(err, 0);
n = 0;
/* Loop on all the lat/lon/values. */
while (grib_iterator_next(iter, &lat, &lon, &value)) {
/* You can now print lat and lon, */
printf("- %d - lat=%.6e lon=%.6e value=", n, lat, lon);
/* decide what to print if a missing value is found. */
if (bitmapPresent && value == missingValue) printf("missing\n");
/* and print the value if is not missing. */
else
printf("%f\n", value);
n++;
}
/* At the end the iterator is deleted to free memory. */
grib_iterator_delete(iter);
/* At the end the grib_handle is deleted to free memory. */
grib_handle_delete(h);
}
fclose(in);
return 0;
}
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