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! (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: Practical example of an ensemble mean using grib_api
!
!
! Author: Cristian D Codorean
!
!
program ensemble_mean
use grib_api
implicit none
character(len=100) :: file_name,out_file
integer :: ifile,ofile
integer :: igrib,ogrib
integer :: numberOfValues, nMessages
integer :: iret
real(8), dimension(:), allocatable :: values,sums
! --- get input arguments
call getarg(1,file_name)
call getarg(2,out_file)
call grib_open_file(ifile,file_name,'r')
call grib_open_file(ofile,out_file,'w')
! --- count number of messages in grib
call grib_count_in_file(ifile,nMessages)
call grib_new_from_file(ifile,igrib,iret)
! --- create ouput grib from this one
call grib_clone(igrib,ogrib)
! --- get the number of values, we suppose all messages have
! - the same size for the sake of this example
call grib_get(igrib,'numberOfValues',numberOfValues)
! --- one should check if allocation was successfull
allocate(values(numberOfValues))
allocate(sums(numberOfValues))
! --- compute the ensemble mean
sums = 0
do while (iret/=GRIB_END_OF_FILE)
call grib_get(igrib,'values',values)
sums = sums + values
call grib_new_from_file(ifile,igrib,iret)
end do
sums = sums/nMessages
! --- write to the out file
call grib_set(ogrib,'values',sums)
call grib_write(ogrib,ofile)
! --- release mem
deallocate(values)
deallocate(sums)
call grib_release(igrib)
call grib_close_file(ifile)
call grib_close_file(ofile)
end program ensemble_mean
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