eccodes/examples/C/grib_print_data.c

90 lines
2.4 KiB
C

/*
* 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.
*/
/*
* C Implementation: grib_print_data
*
* Description: prints all the data contained in a GRIB file
*
*/
#include <stdio.h>
#include <stdlib.h>
#include "eccodes.h"
void usage(const char* prog) {
printf("usage: %s filename\n",prog);
exit(1);
}
int main(int argc, char** argv)
{
int err = 0,i;
double *values = NULL;
double max,min,average;
size_t values_len= 0;
FILE* in = NULL;
char* filename ;
codes_handle *h = NULL;
if (argc<2) usage(argv[0]);
filename=argv[1];
in = fopen(filename,"r");
if(!in) {
printf("ERROR: unable to open file %s\n",filename);
return 1;
}
/* create new handle from a message in a file*/
h = codes_handle_new_from_file(0, in, PRODUCT_GRIB, &err);
if (h == NULL) {
printf("Error: unable to create handle from file %s\n",filename);
}
/* 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);
for(i = 0; i < values_len; i++)
printf("%d %.10e\n",i,values[i]);
free(values);
CODES_CHECK(codes_get_double(h,"max",&max),0);
CODES_CHECK(codes_get_double(h,"min",&min),0);
CODES_CHECK(codes_get_double(h,"average",&average),0);
printf("%d values found in %s\n",(int)values_len,filename);
printf("max=%.10e min=%.10e average=%.10e\n",max,min,average);
{
/* Example of accessing specific elements from data values */
int i=0;
const int NUM = 3;
int index_arr[] = {0, values_len/2, values_len-1};
double vals_arr[3] = {0, 0, 0};
CODES_CHECK(codes_get_double_elements(h, "values", index_arr, NUM, vals_arr), 0);
for (i=0; i<NUM; ++i){
printf("value at index %d = %.10e\n", index_arr[i], vals_arr[i]);
}
}
codes_handle_delete(h);
fclose(in);
return 0;
}