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Description

This example shows: how to get values using keys from GRIB messages

Source code

Tabs Container
directionhorizontal


Tabs Page
titleCFortran 90


Code Block
languagecppnone
titlegrib_get_keys.cf90
linenumbersfalse
/*
 *! (C) Copyright 2005-2015 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) {
!
!
program grib_get_keys
  use eccodes
  implicit none

  integer                            ::  ifile
  integer                            ::  iret
  integer                            ::  igrib
  real                           printf("ERROR: unable to open file %s\n",filename);::  latitudeOfFirstPointInDegrees
  real      return 1;
    }

    /* create new handle from a message in a file*/
    h = codes_handle_new_from_file(0, in, PRODUCT_GRIB, &err); ::  longitudeOfFirstPointInDegrees
  real  if   (h == NULL) {
        printf("Error: unable to create handle from file %s\n",filename);
             }

  ::  /*latitudeOfLastPointInDegrees
 Store thereal 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*/longitudeOfLastPointInDegrees
  integer  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);

          ::  numberOfPointsAlongAParallel
  integer    /* 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);::  numberOfPointsAlongAMeridian
  real,  printf("longitudeOfFirstGridPointInDegrees=%g\n",longitudeOfFirstGridPointInDegrees);

 dimension(:), allocatable   /* get:: as a double*/values
  integer  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);

numberOfValues
  real  /* 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;::  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
        /* Now retrieve the value of the key "file" */! Key value is not missing so get as an integer
        char file[256]={0,};call codes_get(igrib,'Ni',numberOfPointsAlongAParallel)
        CODES_CHECK(codes_get_length(h, "file", &len),0);write(*,*) 'numberOfPointsAlongAParallel=', &
             numberOfPointsAlongAParallel
  assert(len == 1+strlen(filename)); else
        codes_get_string(h, "file", file, &len);write(*,*) 'numberOfPointsAlongAParallel is missing'
    endif

    eq! Get = strcmp(file, filename);as an integer
    call codes_get(igrib,'Nj',numberOfPointsAlongAMeridian)
    assertwrite( eq == 0 );
*,*) 'numberOfPointsAlongAMeridian=', &
     }

    codes_handle_delete(h);numberOfPointsAlongAMeridian

    fclose(in);
    return 0;
}
Tabs Page
titleFortran 90
Code Block
languagenone
titlegrib_get_keys.f90
linenumbersfalse
! Copyright 2005-2015 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   ! 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=', &
         ::  ifilelatitudeOfLastPointInDegrees

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

    ! Get the size of the values array
   :: call codes_get_size(igrib,'values',numberOfValues)
  real    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 latitudeOfFirstPointInDegreesminval(values)
  real   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)

    ::  longitudeOfFirstPointInDegrees
  realwrite(*,*)'There are ',numberOfValues, &
          ' average is ',average, &
          ' min is ',  min_val, &
  ::  latitudeOfLastPointInDegrees
  real    ' 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



Tabs Page
titlePython


Code Block
languagepython
titlegrib_get_keys.py
linenumbersfalse
# (C) ::Copyright  longitudeOfLastPointInDegrees
  integer                            ::  numberOfPointsAlongAParallel
  integer                            ::  numberOfPointsAlongAMeridian
  real, dimension(:), allocatable    ::  values
  integer    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',
        ::  numberOfValues'latitudeOfFirstGridPointInDegrees',
  real      'longitudeOfFirstGridPointInDegrees',
        'latitudeOfLastGridPointInDegrees',
        'longitudeOfLastGridPointInDegrees',
    ]

    while ::  average,min_val, max_val1:
  integer      gid = codes_grib_new_from_file(f)
        if gid is None:
         ::  is_missing, is_defined
   break

  call codes_open_file(ifile, &
    for key  '../../data/reduced_latlon_surface.grib1','r')in keys:
  
  ! Loop on all the messages in a file.
try:
         
  !     aprint(' new grib%s: message%s' is% loaded from file(key, codes_get(gid, key)))
  !     igrib is the grib id toexcept beKeyValueNotFoundError usedas inerr:
 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
# Full list of exceptions here:
              is_missing=0;
  #   call codes_is_missing(igrib,'Ni',is_missing);https://confluence.ecmwf.int/display/ECC/Python+exception+classes
     if  ( is_missing /= 1 ) then
    print('  Key="%s" was !not found: %s' %  get as a integer
(key, err.msg))
           call codes_get(igrib,'Ni',numberOfPointsAlongAParallel)  except CodesInternalError as err:
        write(*,*) 'numberOfPointsAlongAParallel=', &
      print('Error with key="%s" : %s' %  numberOfPointsAlongAParallel(key, err.msg))

     else
   print('There are %d values, average is write(*%f,*) 'numberOfPointsAlongAParallelmin is missing'
%f, max is %f'  endif     % (
     
     !check for existence of keys
 codes_get_size(gid, 'values'),
      is_defined=0;
     call codes_is_definedget(igribgid, 'editionaverage'),is_defined);
     if ( is_defined == 0 ) then
      codes_get(gid, 'min'),
            writecodes_get(0gid,*) 'ERROR: An expected key was not defined!!'
  max')
        ))

       call exitcodes_release(1gid)

     endif
 f.close()


def main():
    call codes_is_defined(igrib,'ThisIsNoLoveSong',is_defined);try:
     if ( is_defined == 1 ) then
     example()
    except CodesInternalError as err:
     write(0,*) 'ERROR: An unexpectedif keyVERBOSE:
 was defined!!'
         call exit(1 traceback.print_exc(file=sys.stderr)
     endif

   else:
  !     get as a integer
     call codes_get(igrib,'Nj',numberOfPointsAlongAMeridian) sys.stderr.write(err.msg + '\n')

     write(*,*) 'numberOfPointsAlongAMeridian=', &
 return         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
1


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



Tabs Page
titleC


Code Block
languagecpp
titlegrib_get_keys.c
linenumbersfalse
/*
 * (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++
Tabs Page
titlePython
Code Block
languagepython
titlegrib_get_keys.py
linenumbersfalse
# Copyright 2005-2015 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)

    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:
            if not codes_is_defined(gid,key): raise Exception("Key was not defined")
        average += values[i];

  print '%s=%s' %average (key,codes_get(gid,key))

        if codes_is_defined(gid,"A_very_silly_girl"): raise Exception("Key was defined")/=(double)values_len;

    free(values);

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

    {
        
int eq = 0;
     print 'There are %d values, average is %f, min is %f, max is %f' % (/* Now retrieve the value of the key "file" */
        char file[256]={0,};
         CODES_CHECK(codes_get_size(gid,'values'),length(h, "file", &len),0);
        assert(len == 1+strlen(filename));
         codes_get_string(gid,'average'),
  h, "file", file, &len);
        eq        codes_get(gid,'min'),= strcmp(file, filename);
        if (eq != 0) assert(!"file and filename    codes_get(gid,'max')not equal");
    }

    {
        )

/* Example of getting bytes */
   codes_release(gid)

    f.close()

def main():
    try: const char* name = "reservedNeedNotBePresent";
        example()
    except CodesInternalError,err:
unsigned char* byte_val = NULL ;
        size_t keySize if= VERBOSE:0;
        CODES_CHECK(codes_get_size(h, name,   traceback.print_exc(file=sys.stderr)&keySize), 0);
        else:
   byte_val = (unsigned char*)malloc(keySize*sizeof(char));
         print >>sys.stderr,err.msg

    GRIB_CHECK(codes_get_bytes(h, name, byte_val, &keySize), name);
    return 1}

if  __name__ == "codes__main__":handle_delete(h);

    sys.exit(main())return 0;
}