mirror of https://github.com/ecmwf/eccodes.git
96 lines
2.8 KiB
C
96 lines
2.8 KiB
C
/*
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* (C) Copyright 2005- ECMWF.
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*
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* This software is licensed under the terms of the Apache Licence Version 2.0
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* which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
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*
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* In applying this licence, ECMWF does not waive the privileges and immunities granted to it by
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* virtue of its status as an intergovernmental organisation nor does it submit to any jurisdiction.
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*/
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/*
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* C Implementation: grib_iterator
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*
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* Description: how to use an iterator on lat/lon/values for GRIB messages
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*
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include "grib_api.h"
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static void usage(const char* prog)
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{
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printf("Usage: %s grib_file\n", prog);
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exit(1);
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}
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int main(int argc, char** argv)
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{
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FILE* in = NULL;
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int err = 0;
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double lat, lon, value;
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double missingValue = 1e+20; /* A value out of range */
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int n = 0;
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long bitmapPresent = 0;
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char* filename = NULL;
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/* Message handle. Required in all the ecCodes calls acting on a message.*/
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grib_handle* h = NULL;
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/* Iterator on lat/lon/values.*/
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grib_iterator* iter = NULL;
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if (argc != 2) usage(argv[0]);
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filename = argv[1];
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in = fopen(filename, "rb");
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if (!in) {
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fprintf(stderr, "Error: unable to open file %s\n", filename);
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return 1;
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}
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/* Loop on all the messages in a file.*/
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while ((h = grib_handle_new_from_file(0, in, &err)) != NULL) {
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/* Check of errors after reading a message. */
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if (err != GRIB_SUCCESS) GRIB_CHECK(err, 0);
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/* Check if a bitmap applies */
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GRIB_CHECK(grib_get_long(h, "bitmapPresent", &bitmapPresent), 0);
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if (bitmapPresent) {
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/* Set the double representing the missing value in the field. */
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/* Choose a missingValue that does not correspond to any real value in the data array */
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GRIB_CHECK(grib_set_double(h, "missingValue", missingValue), 0);
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}
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/* A new iterator on lat/lon/values is created from the message handle h. */
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iter = grib_iterator_new(h, 0, &err);
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if (err != GRIB_SUCCESS) GRIB_CHECK(err, 0);
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n = 0;
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/* Loop on all the lat/lon/values. */
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while (grib_iterator_next(iter, &lat, &lon, &value)) {
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/* You can now print lat and lon, */
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printf("- %d - lat=%.6e lon=%.6e value=", n, lat, lon);
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/* decide what to print if a missing value is found. */
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if (bitmapPresent && value == missingValue) printf("missing\n");
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/* and print the value if is not missing. */
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else
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printf("%f\n", value);
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n++;
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}
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/* At the end the iterator is deleted to free memory. */
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grib_iterator_delete(iter);
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/* At the end the grib_handle is deleted to free memory. */
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grib_handle_delete(h);
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}
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fclose(in);
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return 0;
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}
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