grib_get_keys

! (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: how to get values using keys from GRIB messages
!
!
program grib_get_keys
  use eccodes
  implicit none

  integer                            ::  ifile
  integer                            ::  iret
  integer                            ::  igrib
  real                               ::  latitudeOfFirstPointInDegrees
  real                               ::  longitudeOfFirstPointInDegrees
  real                               ::  latitudeOfLastPointInDegrees
  real                               ::  longitudeOfLastPointInDegrees
  integer                            ::  numberOfPointsAlongAParallel
  integer                            ::  numberOfPointsAlongAMeridian
  real, dimension(:), allocatable    ::  values
  integer                            ::  numberOfValues
  real                               ::  average,min_val, max_val
  integer                            ::  is_missing
  character(len=10)                  ::  open_mode='r'

  call codes_open_file(ifile, &
       '../../data/reduced_latlon_surface.grib1', open_mode)

  ! Loop on all the messages in a file.

  ! A new GRIB message is loaded from file
  ! igrib is the grib id to be used in subsequent calls
  call  codes_grib_new_from_file(ifile,igrib, iret)

  LOOP: DO WHILE (iret /= CODES_END_OF_FILE)

    ! Check if the value of the key is MISSING
    is_missing=0;
    call codes_is_missing(igrib,'Ni',is_missing);
    if ( is_missing /= 1 ) then
        ! Key value is not missing so get as an integer
        call codes_get(igrib,'Ni',numberOfPointsAlongAParallel)
        write(*,*) 'numberOfPointsAlongAParallel=', &
             numberOfPointsAlongAParallel
    else
        write(*,*) 'numberOfPointsAlongAParallel is missing'
    endif

    ! Get as an integer
    call codes_get(igrib,'Nj',numberOfPointsAlongAMeridian)
    write(*,*) 'numberOfPointsAlongAMeridian=', &
         numberOfPointsAlongAMeridian

    ! Get as a real
    call codes_get(igrib, 'latitudeOfFirstGridPointInDegrees', &
          latitudeOfFirstPointInDegrees)
    write(*,*) 'latitudeOfFirstGridPointInDegrees=', &
          latitudeOfFirstPointInDegrees

    ! Get as a real
    call codes_get(igrib, 'longitudeOfFirstGridPointInDegrees', &
          longitudeOfFirstPointInDegrees)
    write(*,*) 'longitudeOfFirstGridPointInDegrees=', &
          longitudeOfFirstPointInDegrees

    ! Get as a real
    call codes_get(igrib, 'latitudeOfLastGridPointInDegrees', &
          latitudeOfLastPointInDegrees)
    write(*,*) 'latitudeOfLastGridPointInDegrees=', &
          latitudeOfLastPointInDegrees

    ! Get as a real
    call codes_get(igrib, 'longitudeOfLastGridPointInDegrees', &
          longitudeOfLastPointInDegrees)
    write(*,*) 'longitudeOfLastGridPointInDegrees=', &
          longitudeOfLastPointInDegrees

    ! Get the size of the values array
    call codes_get_size(igrib,'values',numberOfValues)
    write(*,*) 'numberOfValues=',numberOfValues

    allocate(values(numberOfValues), stat=iret)
    ! Get data values
    call codes_get(igrib,'values',values)
    call codes_get(igrib,'min',min_val) ! can also be obtained through minval(values)
    call codes_get(igrib,'max',max_val) ! can also be obtained through maxval(values)
    call codes_get(igrib,'average',average) ! can also be obtained through maxval(values)

    deallocate(values)

    write(*,*)'There are ',numberOfValues, &
          ' average is ',average, &
          ' min is ',  min_val, &
          ' max is ',  max_val

    call codes_release(igrib)

    call codes_grib_new_from_file(ifile,igrib, iret)

  end do LOOP

  call codes_close_file(ifile)

end program grib_get_keys

# (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.

import traceback
import sys

from eccodes import *

INPUT = '../../data/reduced_latlon_surface.grib1'
VERBOSE = 1  # verbose error reporting


def example():
    f = open(INPUT, 'rb')

    keys = [
        'Ni',
        'Nj',
        'latitudeOfFirstGridPointInDegrees',
        'longitudeOfFirstGridPointInDegrees',
        'latitudeOfLastGridPointInDegrees',
        'longitudeOfLastGridPointInDegrees',
    ]

    while 1:
        gid = codes_grib_new_from_file(f)
        if gid is None:
            break

        for key in keys:
            try:
                print('  %s: %s' % (key, codes_get(gid, key)))
            except KeyValueNotFoundError as err:
                # Full list of exceptions here:
                #   https://confluence.ecmwf.int/display/ECC/Python+exception+classes
                print('  Key="%s" was not found: %s' % (key, err.msg))
            except CodesInternalError as err:
                print('Error with key="%s" : %s' % (key, err.msg))

        print('There are %d values, average is %f, min is %f, max is %f' % (
            codes_get_size(gid, 'values'),
            codes_get(gid, 'average'),
            codes_get(gid, 'min'),
            codes_get(gid, 'max')
        ))

        codes_release(gid)

    f.close()


def main():
    try:
        example()
    except CodesInternalError as err:
        if VERBOSE:
            traceback.print_exc(file=sys.stderr)
        else:
            sys.stderr.write(err.msg + '\n')

        return 1


if __name__ == "__main__":
    sys.exit(main())

/*
 * (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;
    double *values = NULL;
    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 average = 0;
    char* packingType = NULL;

    FILE* in = NULL;
    const char* filename = "../../data/regular_latlon_surface.grib1";
    codes_handle *h = NULL;

    in = fopen(filename,"r");
    if(!in) {
        printf("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) {
        printf("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);

    values = (double*)malloc(values_len*sizeof(double));

    /* get data values*/
    CODES_CHECK(codes_get_double_array(h,"values",values,&values_len),0);

    average = 0;
    for(i = 0; i < values_len; i++)
        average += values[i];

    average /=(double)values_len;

    free(values);

    printf("There are %d values, average is %g\n",(int)values_len,average);

    {
        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(char));
        GRIB_CHECK(codes_get_bytes(h, name, byte_val, &keySize), name);
    }

    codes_handle_delete(h);

    return 0;
}