Description

This example shows: set the data contained in a GRIB file. In this example no missing values are present. If there are missing values, refer to: grib_set_bitmap

Source code

grib_set_data.f90
! (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.
!
!  Description: set the data contained in a GRIB file.
!               In this example no missing values are present.
!               If there are missing values, refer to: grib_set_bitmap
!
program set_data
  use eccodes
  implicit none
  integer                         :: outfile
  integer                         :: i, igrib, iret, numberOfValues, cnt
  real                            :: d, e
  real, dimension(:), allocatable :: values
  integer, parameter              :: max_strsize = 200
  character(len=max_strsize)      :: outfile_name

  call getarg(1, outfile_name)
  call codes_open_file(outfile,outfile_name,'w')

  ! Note: the full name of the sample file is "regular_ll_pl_grib1.tmpl"
  ! Sample files are stored in the samples directory (use codes_info to
  ! see where that is).  The default sample path can be changed by
  ! setting the environment variable ECCODES_SAMPLES_PATH
  call codes_grib_new_from_samples(igrib, 'regular_ll_pl_grib1')

  ! Here we're changing the data values only, so the number of values
  ! will be the same as the sample GRIB.
  ! But if your data array has a different size, then specify the grid geometry
  ! (e.g. keys Ni, Nj etc) and set the correct number of data values
  call codes_get_size(igrib,'values',numberOfValues)

  allocate(values(numberOfValues), stat=iret)
  d = 10e-8
  e = d
  cnt = 1
  do i=1,numberOfValues
    if (cnt>100) then
      e = e*10
      cnt=1
    endif
    values(i) = d
    !print *, values(i)
    d = d + e
    cnt = cnt + 1
  end do

  call codes_set(igrib, 'bitsPerValue', 16)

  ! set data values
  call codes_set(igrib,'values', values)
  call codes_write(igrib,outfile)
  call codes_release(igrib)
  deallocate(values)

end program set_data
grib_set_data.c
/*
 * (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_set_data
 *
 * Description: set the data contained in a GRIB file.
 *              In this example no missing values are present
 *              If there are missing values, refer to: grib_set_bitmap
 */
#include <stdio.h>
#include <stdlib.h>

#include "eccodes.h"

static void usage(const char* prog)
{
    printf("usage: %s out.grib\n",prog);
    exit(1);
}

int main(int argc, char** argv)
{
    int i;
    double *values = NULL;
    size_t values_len= 0;

    /* Note: the full name of the sample file is "regular_ll_pl_grib1.tmpl" */
    /* Sample files are stored in the samples directory (use codes_info to  */
    /* see where that is).  The default sample path can be changed by       */
    /* setting the environment variable ECCODES_SAMPLES_PATH                */
    const char* sample_filename = "regular_ll_pl_grib1";
    /* Here is how you can get the samples path */
    const char* samples_path = codes_samples_path(NULL);
    codes_handle *h = NULL;
    double d,e;
    long count;

    if (argc!=2) usage(argv[0]);
    /* create new handle from message in sample file */
    printf("Using samples path: %s\n", samples_path);
    h = codes_grib_handle_new_from_samples(0, sample_filename);
    if (h == NULL) {
        printf("Error: unable to create handle from sample file %s\n", sample_filename);
        exit(1);
    }

    /* Here we're changing the data values only, so the number of values */
    /* will be the same as the sample GRIB. */
    /* But if your data array has a different size, then specify the grid geometry */
    /* (e.g. keys Ni, Nj etc) and set the correct number of data values */
    CODES_CHECK(codes_get_size(h, "values", &values_len),0);

    values = (double*)malloc(values_len*sizeof(double));
    d=10e-8;
    e=d;
    count=1;
    for (i=0;i<values_len;i++) {
        if (count>100) {e*=10; count=1;}
        values[i]=d;
        /*printf("%g \n",values[i]);*/
        d+=e;
        count++;
    }

    CODES_CHECK(codes_set_long(h,"bitsPerValue",16),0);

    /* set data values */
    CODES_CHECK(codes_set_double_array(h,"values",values,values_len),0);

    CODES_CHECK(codes_write_message(h, argv[1], "w"), 0);

    free(values);
    codes_handle_delete(h);

    return 0;
}