eccodes/tests/grib_read_index.cc

/*
 * (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.
 */

#include "grib_api.h"

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

int main(int argc, char* argv[])
{
    grib_index* index = NULL;
    grib_handle* h    = NULL;
    long *steps, *levels, *numbers;
    char** shortNames = 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]);

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

    index = grib_index_read(0, "out.gribidx", &ret);
    GRIB_CHECK(ret, 0);

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

    /* get the number of distinct values of "step" in the index */
    GRIB_CHECK(grib_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 */
    GRIB_CHECK(grib_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"*/
    GRIB_CHECK(grib_index_get_size(index, "level", &levelSize), 0);
    levels = (long*)malloc(sizeof(long) * levelSize);
    if (!levels) exit(1);
    /*same as for "step"*/
    GRIB_CHECK(grib_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"*/
    GRIB_CHECK(grib_index_get_size(index, "number", &numberSize), 0);
    numbers = (long*)malloc(sizeof(long) * numberSize);
    if (!numbers) exit(1);
    /*same as for "step"*/
    GRIB_CHECK(grib_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"*/
    GRIB_CHECK(grib_index_get_size(index, "shortName", &shortNameSize), 0);
    shortNames = (char**)malloc(sizeof(char*) * shortNameSize);
    if (!shortNames) exit(1);
    /*same as for "step"*/
    GRIB_CHECK(grib_index_get_string(index, "shortName", shortNames, &shortNameSize), 0);
    printf("shortNameSize=%ld\n", (long)shortNameSize);
    for (i = 0; i < shortNameSize; i++)
        printf("%s ", shortNames[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] */
        grib_index_select_string(index, "shortName", shortNames[i]);

        for (l = 0; l < levelSize; l++) {
            /* select the grib with level=level[i] */
            grib_index_select_long(index, "level", levels[l]);

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

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

                    /* create a new grib_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
                     * constrants */
                    while ((h = grib_handle_new_from_index(index, &ret)) != NULL) {
                        count++;
                        if (ret) {
                            printf("error: %d\n", ret);
                            exit(ret);
                        }
                        lenshortName = 200;
                        grib_get_string(h, "shortName", oshortName, &lenshortName);
                        grib_get_long(h, "level", &olevel);
                        grib_get_long(h, "number", &onumber);
                        grib_get_long(h, "step", &ostep);
                        printf("shortName=%s ", oshortName);
                        printf("level=%ld ", olevel);
                        printf("number=%ld ", onumber);
                        printf("step=%ld \n", ostep);
                        grib_handle_delete(h);
                    }
                    if (ret != GRIB_END_OF_INDEX) {
                        printf("error: %s\n", grib_get_error_message(ret));
                        exit(ret);
                    }
                }
            }
        }
    }
    printf("  %d messages selected\n", count);
    free(levels);
    free(steps);
    free(numbers);
    for (i = 0; i < shortNameSize; i++)
        free(shortNames[i]);
    free(shortNames);
    grib_index_delete(index);

    return 0;
}