mirror of https://github.com/ecmwf/eccodes.git
113 lines
4.2 KiB
C
113 lines
4.2 KiB
C
/*
|
|
* 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 octect 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;
|
|
|
|
}
|