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Description

This example shows: how to read values of different type of keys from BUFR messages.

Source code

bufr_get_keys.f90
!
!Copyright 2005-2017 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.
!
!
! FORTRAN 90 Implementation: bufr_get_keys
!
! Description: how to read values of different type of keys from BUFR messages.
!
!
program bufr_get_keys
use eccodes
implicit none
integer            :: ifile
integer            :: iret
integer            :: ibufr
integer            :: i, count=0
integer(kind=4)    :: blockNumber,stationNumber
real(kind=8)       :: t2m
integer(kind=4), dimension(:), allocatable    :: descriptors
real(kind=8), dimension(:), allocatable       :: values
character(len=9)   :: typicalDate

  call codes_open_file(ifile,'../../data/bufr/syno_multi.bufr','r')

  ! The first bufr message is loaded from file,
  ! ibufr is the bufr id to be used in subsequent calls
  call codes_bufr_new_from_file(ifile,ibufr,iret)

  do while (iret/=CODES_END_OF_FILE)

    ! Get and print some keys form the BUFR header
    write(*,*) 'message: ',count

    ! We need to instruct ecCodes to expand all the descriptors
    ! i.e. unpack the data values
    call codes_set(ibufr,"unpack",1);

    ! Get as character
    call codes_get(ibufr,'typicalDate',typicalDate)
    write(*,*) '  typicalDate:',typicalDate

    ! Get as integer
    call codes_get(ibufr,'blockNumber',blockNumber);
    write(*,*) '  blockNumber:',blockNumber

    ! Get as integer
    call codes_get(ibufr,'stationNumber',stationNumber);
    write(*,*) '  stationNumber:',stationNumber

    ! get as real
    call codes_get(ibufr,'airTemperatureAt2M',t2m);
    write(*,*) '  airTemperatureAt2M:',t2m

    ! ---- array of integer ----------------

    ! get the expanded descriptors
    call codes_get(ibufr,'bufrdcExpandedDescriptors',descriptors)

    do i=1,size(descriptors)
        write(*,*) '  ',i,descriptors(i)
    enddo

    ! ---- array of real ----------------

    ! Get the expanded data values
    call codes_get(ibufr,'numericValues',values)

    do i=1,size(values)
        write(*,*) '  ',i,values(i)
    enddo

    ! Get as character
    call codes_get(ibufr,'typicalDate',typicalDate)
    write(*,*) '  typicalDate:',typicalDate

    ! Free arrays
    deallocate(values)
    deallocate(descriptors)

    ! Release the bufr message
    call codes_release(ibufr)

    ! Load the next bufr message
    call codes_bufr_new_from_file(ifile,ibufr,iret)

    count=count+1

  end do

  ! Close file
  call codes_close_file(ifile)

end program bufr_get_keys
bufr_get_keys.py
# Copyright 2005-2017 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.

#
# Python implementation: bufr_get_keys
#
# Description: how to read values of different type of keys from BUFR messages.
#
#

from __future__ import print_function
import traceback
import sys

from eccodes import *

INPUT = '../../data/bufr/syno_multi.bufr'
VERBOSE = 1  # verbose error reporting


def example():
    # open bufr file
    f = open(INPUT)

    cnt = 0

    # loop for the messages in the file
    while 1:
        # get handle for message
        bufr = codes_bufr_new_from_file(f)
        if bufr is None:
            break

        print("message: %s" % cnt)

        # we need to instruct ecCodes to expand all the descriptors
        # i.e. unpack the data values
        codes_set(bufr, 'unpack', 1)

        # ---------------------------------------------
        # get values for keys holding a single value
        # ---------------------------------------------
        # Native type integer
        key = 'blockNumber'

        try:
            print('  %s: %s' % (key, codes_get(bufr, key)))
        except CodesInternalError as err:
            print('Error with key="%s" : %s' % (key, err.msg))

        # Native type integer
        key = 'stationNumber'
        try:
            print('  %s: %s' % (key, codes_get(bufr, key)))
        except CodesInternalError as err:
            print('Error with key="%s" : %s' % (key, err.msg))

        # Native type float
        key = 'airTemperatureAt2M'
        try:
            print('  %s: %s' % (key, codes_get(bufr, key)))
        except CodesInternalError as err:
            print('Error with key="%s" : %s' % (key, err.msg))

        # Native type string
        key = 'typicalDate'
        try:
            print('  %s: %s' % (key, codes_get(bufr, key)))
        except CodesInternalError as err:
            print('Error with key="%s" : %s' % (key, err.msg))

        # --------------------------------
        # get values for an array
        # --------------------------------
        # Native type integer
        key = 'bufrdcExpandedDescriptors'

        # get size
        num = codes_get_size(bufr, key)
        print('  size of %s is: %s' % (key, num))

        # get values
        values = codes_get_array(bufr, key)
        for i in range(len(values)):
            print("   %d %06d" % (i + 1, values[i]))

        # Native type float
        key = 'numericValues'

        # get size
        num = codes_get_size(bufr, key)
        print('  size of %s is: %s' % (key, num))

        # get values
        values = codes_get_array(bufr, key)
        for i in range(len(values)):
            print("   %d %.10e" % (i + 1, values[i]))

        cnt += 1

        # delete handle
        codes_release(bufr)

    # close the file
    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())
bufr_get_keys.c
/*
 * Copyright 2005-2017 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: bufr_get_keys
 *
 * Description: how to read values of different type of keys from BUFR messages.
 *
 */

#include "eccodes.h"

int main(int argc,char* argv[])
{
    FILE* in = NULL;

    /* message handle. Required in all the eccodes calls acting on a message.*/
    codes_handle* h=NULL;

    long *descriptors=NULL;
    double *values = NULL;
    char* typicalDate= NULL;
    long longVal;
    double doubleVal;
    size_t values_len=0, desc_len=0, len=0;
    int i, err=0;
    int cnt=0;
    const char* infile = "../../data/bufr/syno_multi.bufr";

    in=fopen(infile,"r");
    if (!in) {
        printf("ERROR: unable to open file %s\n", infile);
        return 1;
    }

    /* loop over the messages in the bufr file */
    while ((h = codes_handle_new_from_file(NULL, in, PRODUCT_BUFR, &err)) != NULL || err != CODES_SUCCESS)
    {
        if (h == NULL) {
            printf("Error: unable to create handle for message %d\n",cnt);
            cnt++;
            continue;
        }

        printf("message: %d\n",cnt);

        /* we need to instruct ecCodes to expand the descriptors
          i.e. unpack the data values */
        CODES_CHECK(codes_set_long(h, "unpack", 1),0);

        /* read and print some data values */

        /* long value */
        CODES_CHECK(codes_get_long(h, "blockNumber", &longVal),0);
        printf("  blockNumber: %ld\n", longVal);

        /* long value */
        CODES_CHECK(codes_get_long(h, "stationNumber", &longVal),0);
        printf("  stationNumber: %ld\n", longVal);

        /* double value */
        CODES_CHECK(codes_get_double(h, "airTemperatureAt2M", &doubleVal),0);
        printf("  airTemperatureAt2M: %f\n", doubleVal);

        /* ---- string value  -----------------*/

        /* get the size and allocate memory*/
        CODES_CHECK(codes_get_length(h, "typicalDate", &len), 0);
        typicalDate = (char*)malloc(len*sizeof(char));

        /* get the values*/
        codes_get_string(h, "typicalDate", typicalDate, &len);
        printf("  typicalDate: %s\n", typicalDate);

        /* ---- array of long ----------------*/

        /* get the size and allocate memory*/
        CODES_CHECK(codes_get_size(h, "bufrdcExpandedDescriptors", &desc_len),0);
        descriptors = (long*)malloc(desc_len*sizeof(long));

        /* get the values */
        CODES_CHECK(codes_get_long_array(h, "bufrdcExpandedDescriptors", descriptors, &desc_len),0);
        printf("  bufrdcExpandedDescriptors:\n");
        for(i = 0; i < desc_len; i++)
        {
            printf("   %ld\n",descriptors[i]);
        }

        /* ---- array of double ---------------*/

        /* get the size and allocate memory*/
        CODES_CHECK(codes_get_size(h, "numericValues", &values_len),0);
        values = (double*)malloc(values_len*sizeof(double));

        /* get the values*/
        CODES_CHECK(codes_get_double_array(h, "numericValues", values, &values_len),0);
        printf("  numericValues:\n");
        for(i = 0; i < values_len; i++)
        {
            printf("   %.10e\n",values[i]);
        }

        /* free allocated arrays */
        free(descriptors);
        free(values);
        free(typicalDate);

        /* delete handle */
        codes_handle_delete(h);

        cnt++;
    }

    fclose(in);
    return 0;
}

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