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! Copyright 2005-2018 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 create and use an index to access GRIB messages from a file.
!               Demo also loading and writing an index from a file.
!
!
!
program index
  use eccodes
  implicit none

  integer              :: iret
  integer,dimension(:),allocatable           :: step,level,number
  character(len=20),dimension(:),allocatable :: shortName
  integer              :: ostep,olevel,onumber
  character(len=20)    :: oshortName
  integer              :: shortNameSize,numberSize,levelSize,stepSize
  integer              :: i,j,k,l
  integer              :: idx,igrib,count1
  character(len=10)    :: index_file='index.idx'

  ! uncomment following line to load index from file
  !call codes_index_read(idx,index_file)

  ! create an index from a grib file using some keys
  call codes_index_create(idx,'../../data/index.grib','shortName,number,level,step')

  ! get the number of distinct values of shortName in the index
  call codes_index_get_size(idx,'shortName',shortNameSize)
  ! allocate the array to contain the list of distinct shortName
  allocate(shortName(shortNameSize))
  ! get the list of distinct shortName from the index
  call codes_index_get(idx,'shortName',shortName)
  write(*,'(a,i3)') 'shortNameSize=',shortNameSize

  ! get the number of distinct values of number in the index
  call codes_index_get_size(idx,'number',numberSize)
  ! allocate the array to contain the list of distinct numbers
  allocate(number(numberSize))
  ! get the list of distinct numbers from the index
  call codes_index_get(idx,'number',number)
  write(*,'(a,i3)') 'numberSize=',numberSize

  ! get the number of distinct values of level in the index
  call codes_index_get_size(idx,'level',levelSize)
  ! allocate the array to contain the list of distinct levels
  allocate(level(levelSize))
  ! get the list of distinct levels from the index
  call codes_index_get(idx,'level',level)
  write(*,'(a,i3)') 'levelSize=',levelSize

  ! get the number of distinct values of step in the index
  call codes_index_get_size(idx,'step',stepSize)
  ! allocate the array to contain the list of distinct steps
  allocate(step(stepSize))
  ! get the list of distinct steps from the index
  call codes_index_get(idx,'step',step)
  write(*,'(a,i3)') 'stepSize=',stepSize

  count1=0
  do l=1,stepSize ! loop on step
    ! select step=step(l)
    call codes_index_select(idx,'step',step(l))

    do j=1,numberSize ! loop on number
      ! select number=number(j)
      call codes_index_select(idx,'number',number(j))

      do k=1,levelSize ! loop on level
        ! select level=level(k)
        call codes_index_select(idx,'level',level(k))

        do i=1,shortNameSize ! loop on shortName
          ! select shortName=shortName(i)
          call codes_index_select(idx,'shortName',shortName(i))

          call codes_new_from_index(idx,igrib, iret)
          do while (iret /= CODES_END_OF_INDEX)
             count1=count1+1
             call codes_get(igrib,'shortName',oshortName)
             call codes_get(igrib,'number',onumber)
             call codes_get(igrib,'level',olevel)
             call codes_get(igrib,'step',ostep)
             write(*,'(A,A,A,i3,A,i4,A,i3)') 'shortName=',trim(oshortName),&
                     '   number=',onumber,&
                     '   level=' ,olevel, &
                     '   step='  ,ostep

             call codes_release(igrib)
             call codes_new_from_index(idx,igrib, iret)
          end do
          call codes_release(igrib)

        end do ! loop on step
      end do ! loop on level
    end do ! loop on number
  end do ! loop on shortName
  write(*,'(i4,a)') count1,' messages selected'

  ! save the index to a file for later reuse
  call codes_index_write(idx,index_file)

  call codes_index_release(idx)

  deallocate(level)
  deallocate(shortName)
  deallocate(step)
  deallocate(number)

end program index

#
# Copyright 2005-2018 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 create and use an index to access GRIB messages from
# a file

from __future__ import print_function
import traceback
import sys
import os

from eccodes import *

INPUT = '../../data/index.grib'
VERBOSE = 1  # verbose error reporting


def product(*args, **kwds):
    # product('ABCD', 'xy') --> Ax Ay Bx By Cx Cy Dx Dy
    # product(range(2), repeat=3) --> 000 001 010 011 100 101 110 111
    pools = list(map(tuple, args)) * kwds.get('repeat', 1)
    result = [[]]
    for pool in pools:
        result = [x + [y] for x in result for y in pool]
    for prod in result:
        yield tuple(prod)


def example():
    index_keys = ["shortName", "level", "number", "step"]
    index_file = "my.idx"

    iid = None

    if os.path.exists(index_file):
        iid = codes_index_read(index_file)
    else:
        iid = codes_index_new_from_file(INPUT, index_keys)

        # multiple files can be added to an index:
        # codes_index_add_file(iid,"grib file to add")

        codes_index_write(iid, index_file)

    index_vals = []

    for key in index_keys:
        print("%sSize=%d" % (
            key,
            codes_index_get_size(iid, key)
        ))

        key_vals = codes_index_get(iid, key)
        print(" ".join(key_vals))

        index_vals.append(key_vals)

    for prod in product(*index_vals):
        for i in range(len(index_keys)):
            codes_index_select(iid, index_keys[i], prod[i])

        while 1:
            gid = codes_new_from_index(iid)
            if gid is None:
                break
            print(" ".join(["%s=%s" % (key, codes_get(gid, key))
                            for key in index_keys]))
            codes_release(gid)

    codes_index_release(iid)


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())

/*
 * Copyright 2005-2018 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_index
 *
 * Description: How to create and use an index to access GRIB messages from a file
 *
 */

#include "eccodes.h"

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

int main(int argc,char* argv[])
{
    codes_index* index=NULL;
    codes_handle* h=NULL;
    char* infile=NULL;
    long *steps,*levels,*numbers; /* arrays */
    char** shortName=NULL;
    int i,j,k,l;
    size_t stepSize,levelSize,shortNameSize,numberSize;
    long ostep,olevel,onumber;
    char oshortName[200];
    size_t lenshortName=200;
    int ret=0,count=0;

    if (argc != 2) usage(argv[0]);
    infile=argv[1];

    printf("indexing...\n");

    /* Create an index given set of keys*/
    index=codes_index_new(0,"shortName,level,number,step",&ret);
    if (ret) {printf("error: %s\n",codes_get_error_message(ret)); exit(ret);}

    /* Indexes a file */
    ret=codes_index_add_file(index,infile);
    if (ret) {printf("error: %s\n",codes_get_error_message(ret)); exit(ret);}
    printf("end indexing...\n");

    /* get the number of distinct values of "step" in the index */
    CODES_CHECK(codes_index_get_size(index,"step",&stepSize),0);
    steps=(long*)malloc(sizeof(long)*stepSize);
    if (!steps) exit(1);
    /* get the list of distinct steps from the index */
    /* the list is in ascending order */
    CODES_CHECK(codes_index_get_long(index,"step",steps,&stepSize),0);
    printf("stepSize=%ld\n",(long)stepSize);
    for (i=0;i<stepSize;i++) printf("%ld ",steps[i]);
    printf("\n");

    /*same as for "step"*/
    CODES_CHECK(codes_index_get_size(index,"level",&levelSize),0);
    levels=(long*)malloc(sizeof(long)*levelSize);
    if (!levels) exit(1);
    /*same as for "step"*/
    CODES_CHECK(codes_index_get_long(index,"level",levels,&levelSize),0);
    printf("levelSize=%ld\n",(long)levelSize);
    for (i=0;i<levelSize;i++) printf("%ld ",levels[i]);
    printf("\n");

    /*same as for "step"*/
    CODES_CHECK(codes_index_get_size(index,"number",&numberSize),0);
    numbers=(long*)malloc(sizeof(long)*numberSize);
    if (!numbers) exit(1);
    /*same as for "step"*/
    CODES_CHECK(codes_index_get_long(index,"number",numbers,&numberSize),0);
    printf("numberSize=%ld\n",(long)numberSize);
    for (i=0;i<numberSize;i++) printf("%ld ",numbers[i]);
    printf("\n");

    /*same as for "step"*/
    CODES_CHECK(codes_index_get_size(index,"shortName",&shortNameSize),0);
    shortName=(char**)malloc(sizeof(char*)*shortNameSize);
    if (!shortName) exit(1);
    /*same as for "step"*/
    CODES_CHECK(codes_index_get_string(index,"shortName",shortName,&shortNameSize),0);
    printf("shortNameSize=%ld\n",(long)shortNameSize);
    for (i=0;i<shortNameSize;i++) printf("%s ",shortName[i]);
    printf("\n");

    count=0;
    /* nested loops on the keys values of the index */
    /* different order of the nested loops doesn't affect performance*/
    for (i=0;i<shortNameSize;i++) {
        /* select the GRIB with shortName=shortName[i] */
        codes_index_select_string(index,"shortName",shortName[i]);

        for (l=0;l<levelSize;l++) {
            /* select the GRIB with level=levels[il] */
            codes_index_select_long(index,"level",levels[l]);

            for (j=0;j<numberSize;j++) {
                /* select the GRIB with number=numbers[j] */
                codes_index_select_long(index,"number",numbers[j]);

                for (k=0;k<stepSize;k++) {
                    /* select the GRIB with step=steps[k] */
                    codes_index_select_long(index,"step",steps[k]);

                    /* create a new codes_handle from the index with the constraints
                           imposed by the select statements. It is a loop because
                           in the index there could be more than one GRIB with those
                           constraints */
                    while ((h=codes_handle_new_from_index(index,&ret))!=NULL){
                        count++;
                        if (ret) {printf("error: %d\n",ret); exit(ret);}
                        lenshortName=200;
                        codes_get_string(h,"shortName",oshortName,&lenshortName);
                        codes_get_long(h,"level",&olevel);
                        codes_get_long(h,"number",&onumber);
                        codes_get_long(h,"step",&ostep);
                        printf("shortName=%s ",oshortName);
                        printf("level=%ld ",olevel);
                        printf("number=%ld ",onumber);
                        printf("step=%ld \n",ostep);
                        codes_handle_delete(h);
                    }
                    if (ret && ret!=GRIB_END_OF_INDEX ) {printf("error: %s\n",codes_get_error_message(ret)); exit(ret);}
                }
            }
        }
    }
    printf("  %d messages selected\n",count);

    codes_index_write(index,"out.gribidx");
    codes_index_delete(index);

    return 0;
}