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/*
* C Implementation: get_set
*
* Description:
* Example on how to get and set values through key names
* from a grib_handle created by an message in a file.
* All angles are espressed in Degrees though in the
* message can be in millidegrees or microdegrees depending
* on the grib edition number.
* Only angle values in Degrees should be setted and getted
* by the user. Expert users can access the hard coded values
* in the grib message omitting the "InDegrees" suffix, but
* it's worth to notice that units are those appropriate for
* the message edition.
* WARNING: Some variables are dependent.
* For example numberOfPointsAlongAMeridian depends on:
* - jDirectionIncrementInDegrees
* - latitudeOfFirstGridPointInDegrees
* - latitudeOfLastGridPointInDegrees.
* Thus only these last three must be set and the first will
* be available. Inversely if numberOfPointsAlongAMeridian
* is set then jDirectionIncrementInDegrees will be
* automatically calculated and modified in the grib
* message.
* jDirectionIncrementInDegrees, latitudeOfFirstGridPointInDegrees,
* latitudeOfLastGridPointInDegrees are required variables and
* numberOfPointsAlongAMeridian is optional. All the required
* variables must be set when creating a new handle, optional
* ones can be set or not. If an optional variable is set other
* variables are automatically set. Only required variables
* should be set by a user. Only expert users should access
* optional variables and only in particulare cases.
* A list of all the available required keys for a message
* can be obtained using the command line tool grib_dump
* on the message file, or with the keys_iterator function
* (see example keys_iterator.c).
*
* Author: Enrico Fucile <enrico.fucile@ecmwf.int>, (C) 2006
*
* Copyright: See COPYING file that comes with this distribution
*
*/
#include <stdio.h>
#include <unistd.h>
#include "grib_api.h"
int main(int argc, char *argv[])
{
int ret=0;
grib_handle* h;
double* values;
long numberOfPointsAlongAParallel,numberOfPointsAlongAMeridian,numberOfPoints,i,j,k;
/* Option flags used by grib_dump.
* Turn on:
* GRIB_DUMP_FLAG_VALUES to dump values
* GRIB_DUMP_FLAG_OPTIONAL to dump optional keys
* GRIB_DUMP_FLAG_READ_ONLY to dump read_only keys
*/
int option_flags = GRIB_DUMP_FLAG_VALUES
| GRIB_DUMP_FLAG_OPTIONAL
| GRIB_DUMP_FLAG_READ_ONLY;
h = grib_handle_new_from_template(0,"GRIB1");
if(!h) {
printf("ERROR: Unable to create grib handle\n");
exit(1);
}
/* GRIB_CHECK is a macro that translates the error code in a message
* printed on the standard error and exits returning the error code
*/
GRIB_CHECK(grib_set_double(h,"latitudeOfFirstGridPointInDegrees",10),0);
GRIB_CHECK(grib_set_double(h,"longitudeOfFirstGridPointInDegrees",-10),0);
GRIB_CHECK(grib_set_double(h,"latitudeOfLastGridPointInDegrees",-10),0);
GRIB_CHECK(grib_set_double(h,"longitudeOfLastGridPointInDegrees",10),0);
GRIB_CHECK(grib_set_double(h,"jDirectionIncrementInDegrees",0.5),0);
GRIB_CHECK(grib_set_double(h,"iDirectionIncrementInDegrees",0.5),0);
GRIB_CHECK(grib_get_long( h,"numberOfPointsAlongAParallel",&numberOfPointsAlongAParallel),0);
GRIB_CHECK(grib_get_long( h,"numberOfPointsAlongAMeridian",&numberOfPointsAlongAMeridian),0);
numberOfPoints=numberOfPointsAlongAMeridian*numberOfPointsAlongAParallel;
values=(double*)malloc(numberOfPoints*sizeof(double));
for (j=0;j<numberOfPointsAlongAMeridian;j++) {
for (i=0;i<numberOfPointsAlongAParallel;i++) {
k=i+numberOfPointsAlongAParallel*j;
values[k]=50;
}
}
GRIB_CHECK(grib_set_double_array( h,"values",values,numberOfPoints),0);
if (h) {
/* dump key/values pairs according the option_flags and with
* the "serialize" style. Other available styles are:
* - "debug" Dump all keys with octet position
* - "c_code" Dump C code to build the grib file from scratch
*/
grib_dump_content(h,stdout,"serialize",option_flags,NULL);
} else {
printf("Error: unable to create grib_handle\n");
}
return ret;
}
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