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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_get_keys
*
* Description: how to get values using keys from GRIB messages
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include "eccodes.h"
int main(int argc, char** argv)
{
int err = 0;
float* fvalues = NULL; /* data values as floats */
double* dvalues = NULL; /* data values as doubles */
size_t values_len = 0;
size_t i = 0, len = 0;
double latitudeOfFirstGridPointInDegrees;
double longitudeOfFirstGridPointInDegrees;
double latitudeOfLastGridPointInDegrees;
double longitudeOfLastGridPointInDegrees;
double jDirectionIncrementInDegrees;
double iDirectionIncrementInDegrees;
long numberOfPointsAlongAParallel;
long numberOfPointsAlongAMeridian;
double daverage = 0;
float faverage = 0;
char* packingType = NULL;
FILE* in = NULL;
const char* filename = "../../data/regular_latlon_surface.grib1";
codes_handle* h = NULL;
in = fopen(filename, "rb");
if (!in) {
fprintf(stderr, "Error: unable to open file %s\n", filename);
return 1;
}
/* create new handle from the first message in the file*/
h = codes_handle_new_from_file(0, in, PRODUCT_GRIB, &err);
if (h == NULL) {
fprintf(stderr, "Error: unable to create handle from file %s\n", filename);
return 1;
}
fclose(in);
/* store the filename in the key "file" for this handle */
len = strlen(filename);
CODES_CHECK(codes_set_string(h, "file", filename, &len), 0);
/* get as a long*/
CODES_CHECK(codes_get_long(h, "Ni", &numberOfPointsAlongAParallel), 0);
printf("numberOfPointsAlongAParallel=%ld\n", numberOfPointsAlongAParallel);
/* get as a long*/
CODES_CHECK(codes_get_long(h, "Nj", &numberOfPointsAlongAMeridian), 0);
printf("numberOfPointsAlongAMeridian=%ld\n", numberOfPointsAlongAMeridian);
/* get as a double*/
CODES_CHECK(codes_get_double(h, "latitudeOfFirstGridPointInDegrees", &latitudeOfFirstGridPointInDegrees), 0);
printf("latitudeOfFirstGridPointInDegrees=%g\n", latitudeOfFirstGridPointInDegrees);
/* get as a double*/
CODES_CHECK(codes_get_double(h, "longitudeOfFirstGridPointInDegrees", &longitudeOfFirstGridPointInDegrees), 0);
printf("longitudeOfFirstGridPointInDegrees=%g\n", longitudeOfFirstGridPointInDegrees);
/* get as a double*/
CODES_CHECK(codes_get_double(h, "latitudeOfLastGridPointInDegrees", &latitudeOfLastGridPointInDegrees), 0);
printf("latitudeOfLastGridPointInDegrees=%g\n", latitudeOfLastGridPointInDegrees);
/* get as a double*/
CODES_CHECK(codes_get_double(h, "longitudeOfLastGridPointInDegrees", &longitudeOfLastGridPointInDegrees), 0);
printf("longitudeOfLastGridPointInDegrees=%g\n", longitudeOfLastGridPointInDegrees);
/* get as a double*/
CODES_CHECK(codes_get_double(h, "jDirectionIncrementInDegrees", &jDirectionIncrementInDegrees), 0);
printf("jDirectionIncrementInDegrees=%g\n", jDirectionIncrementInDegrees);
/* get as a double*/
CODES_CHECK(codes_get_double(h, "iDirectionIncrementInDegrees", &iDirectionIncrementInDegrees), 0);
printf("iDirectionIncrementInDegrees=%g\n", iDirectionIncrementInDegrees);
/* get as string */
CODES_CHECK(codes_get_length(h, "packingType", &len), 0);
packingType = (char*)malloc(len * sizeof(char));
codes_get_string(h, "packingType", packingType, &len);
printf("packingType=%s\n", packingType);
free(packingType);
/* get the size of the values array*/
CODES_CHECK(codes_get_size(h, "values", &values_len), 0);
fvalues = (float*)malloc(values_len * sizeof(float));
dvalues = (double*)malloc(values_len * sizeof(double));
/* get data values*/
CODES_CHECK(codes_get_float_array(h, "values", fvalues, &values_len), 0);
CODES_CHECK(codes_get_double_array(h, "values", dvalues, &values_len), 0);
faverage = 0;
daverage = 0;
for (i = 0; i < values_len; i++) {
faverage += fvalues[i];
daverage += dvalues[i];
}
faverage /= (float)values_len;
daverage /= (double)values_len;
free(fvalues);
free(dvalues);
printf("There are %zu values, double average is %g\n", values_len, daverage);
printf("There are %zu values, float average is %f\n", values_len, faverage);
{
int eq = 0;
/* now retrieve the value of the key "file" */
char file[256] = {0,};
CODES_CHECK(codes_get_length(h, "file", &len), 0);
assert(len == 1 + strlen(filename));
codes_get_string(h, "file", file, &len);
eq = strcmp(file, filename);
if (eq != 0) assert(!"file and filename not equal");
}
{
/* example of getting bytes */
const char* name = "reservedNeedNotBePresent";
unsigned char* byte_val = NULL;
size_t keySize = 0;
CODES_CHECK(codes_get_size(h, name, &keySize), 0);
byte_val = (unsigned char*)malloc(keySize * sizeof(unsigned char));
GRIB_CHECK(codes_get_bytes(h, name, byte_val, &keySize), name);
free(byte_val);
}
codes_handle_delete(h);
return 0;
}
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