multi.f90

How to decode a grib message containing many fields.

! Copyright 2005-2007 ECMWF
! 
! Licensed under the GNU Lesser General Public License which
! incorporates the terms and conditions of version 3 of the GNU
! General Public License.
! See LICENSE and gpl-3.0.txt for details.
!
!
!  Description: How to decode grib messages containing multiple
!               fields. Try to turn on and off multi support to
!               see the difference. Default is OFF.
!               For all the tools defalut is multi support ON.
!
!
!  Author: Enrico Fucile 
!
!
program multi
  use grib_api
  implicit none
  
  integer              :: iret
  character(len = 256) :: error
  integer(kind = 4)    ::  parameterCategory,parameterNumber,discipline
  integer              :: ifile,igrib

  call grib_open_file(ifile, &
       '../../data/multi.grib2','r')

  !     turn on support for multi fields messages */
  call grib_multi_support_on()

  !     turn off support for multi fields messages */
  !     call grib_multi_support_off()

  call grib_new_from_file(ifile,igrib, iret)
  !     Loop on all the messages in a file.

  do while (iret /= GRIB_END_OF_FILE)

     !     get as a integer*4
     call grib_get(igrib,'discipline',discipline)
     write(*,*) 'discipline=',discipline
     
     !     get as a integer*4
     call grib_get(igrib,'parameterCategory', &
          parameterCategory)
     write(*,*) 'parameterCategory=',parameterCategory
     
     !     get as a integer*4
     call grib_get(igrib,'parameterNumber', &
       parameterNumber)
     write(*,*) 'parameterNumber=',parameterNumber
     
     if ( discipline .eq. 0 .and. parameterCategory .eq. 2) then
        if (parameterNumber .eq. 2) then
        write(*,*) "-------- u -------"
     endif
     if (parameterNumber .eq. 3) then
        write(*,*) "-------- v -------"
     endif
  endif
  
  call grib_release(igrib)
  call grib_new_from_file(ifile,igrib, iret)
  
end do
  call grib_close_file(ifile)

end program multi

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