grib_nearest

! (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 use codes_grib_find_nearest and codes_get_element
!
!
!
program find
  use eccodes
  implicit none
  integer                                      :: npoints
  integer                                      :: infile
  integer                                      :: igrib, ios, i
  real(8), dimension(:), allocatable  :: lats, lons
  real(8), dimension(:), allocatable  :: nearest_lats, nearest_lons
  real(8), dimension(:), allocatable  :: distances, values, lsm_values
  integer(kind=kindOfInt), dimension(:), allocatable  :: indexes

  ! initialization
  open( unit=1, file="../../data/list_points",form="formatted",action="read")
  read(unit=1,fmt=*) npoints
  allocate(lats(npoints))
  allocate(lons(npoints))
  allocate(nearest_lats(npoints))
  allocate(nearest_lons(npoints))
  allocate(distances(npoints))
  allocate(lsm_values(npoints))
  allocate(values(npoints))
  allocate(indexes(npoints))
  do i=1,npoints
    read(unit=1,fmt=*, iostat=ios) lats(i), lons(i)
    if (ios /= 0) then
      npoints = i - 1
      exit
    end if
  end do
  close(unit=1)
  call codes_open_file(infile, &
       '../../data/reduced_gaussian_lsm.grib1','r')

  ! 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(infile,igrib)

  call codes_grib_find_nearest(igrib, .true., lats, lons, nearest_lats, nearest_lons,lsm_values, distances, indexes)
  call codes_release(igrib)

  call codes_close_file(infile)

  ! will apply it to another GRIB
  call codes_open_file(infile, &
       '../../data/reduced_gaussian_pressure_level.grib1','r')
  call codes_grib_new_from_file(infile,igrib)

  call codes_get_element(igrib,"values", indexes, values)
  call codes_release(igrib)
  call codes_close_file(infile)

  do i=1, npoints
    print*,lats(i), lons(i), nearest_lats(i), nearest_lons(i), distances(i), lsm_values(i), values(i)
  end do

  deallocate(lats)
  deallocate(lons)
  deallocate(nearest_lats)
  deallocate(nearest_lons)
  deallocate(distances)
  deallocate(lsm_values)
  deallocate(values)
  deallocate(indexes)

end program find

#
# (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_gaussian_lsm.grib1'
VERBOSE = 1  # verbose error reporting


def example():
    points = ((30, -20), (13, 234))

    f = open(INPUT, 'rb')
    gid = codes_grib_new_from_file(f)

    for lat, lon in points:
        nearest = codes_grib_find_nearest(gid, lat, lon)[0]
        print(lat, lon)
        print(nearest.lat, nearest.lon, nearest.value, nearest.distance,
              nearest.index)

        four = codes_grib_find_nearest(gid, lat, lon, is_lsm=False, npoints=4)
        for i in range(len(four)):
            print("- %d -" % i)
            print(four[i])

        print("-" * 100)

    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: nearest
 *
 * Description: how to get nearest point(s)
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "eccodes.h"

static void usage(const char* prog) {
    printf("Usage: %s grib_file grib_file ...\n",prog);
    exit(1);
}

int main(int argc, char** argv)
{
    int err = 0;
    long step=0;
    size_t nfiles;
    int i=0;
    codes_fieldset* set=NULL;
    codes_handle* h=NULL;
    char param[20]={0,};
    size_t len=20;
    double lats[4]={0,};
    double lons[4]={0,};
    double values[4]={0,};
    double distances[4]={0,};
    int indexes[4]={0,};
    char* order_by="param,step";

    size_t size=4;
    double lat=-40,lon=15;
    int mode=0;
    int count;
    char** filenames;
    codes_nearest* nearest=NULL;

    if (argc < 2) usage(argv[0]);

    nfiles=argc-1;
    filenames=(char**)malloc(sizeof(char*)*nfiles);
    for (i=0;i<nfiles;i++)
        filenames[i]=(char*)strdup(argv[i+1]);

    set=codes_fieldset_new_from_files(0,filenames,nfiles,0,0,0,order_by,&err);
    CODES_CHECK(err,0);

    printf("\nordering by %s\n",order_by);
    printf("\n%d fields in the fieldset\n",codes_fieldset_count(set));
    printf("n,step,param\n");

    mode=CODES_NEAREST_SAME_GRID | CODES_NEAREST_SAME_POINT;
    count=1;

    while ((h=codes_fieldset_next_handle(set,&err))!=NULL) {
        CODES_CHECK(codes_get_long(h,"step",&step),0);
        len=20;
        CODES_CHECK(codes_get_string(h,"shortName",param,&len),0);

        printf("%d %ld %s  ",count,step,param);
        if (!nearest) nearest=codes_grib_nearest_new(h,&err);
        CODES_CHECK(err,0);
        CODES_CHECK(codes_grib_nearest_find(nearest,h,lat,lon,mode,lats,lons,values,distances,indexes,&size),0);
        printf("\nIdx\tlat\tlon\tdist\tval\n");
        for (i=0;i<4;i++) printf("%d\t%.2f\t%.2f\t%g\t%g\n",
                (int)indexes[i],lats[i],lons[i],distances[i],values[i]);
        printf("\n");

        codes_handle_delete(h);
        count++;
    }

    if (nearest) codes_grib_nearest_delete(nearest);

    if (set) codes_fieldset_delete(set);

    return 0;
}