mirror of https://github.com/ecmwf/eccodes.git
126 lines
3.9 KiB
C
126 lines
3.9 KiB
C
/*
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* Copyright 2005-2018 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: ensemble_mean
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*
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* Description: index a GRIB file, select a specific parameter and compute ensemble mean.
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*
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*/
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#include "eccodes.h"
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int main(int argc, char * argv[])
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{
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int ret;
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int i, j;
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int count=0;
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size_t paramIdSize, numberSize, values_len=0;
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char** paramId;
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long* number;
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double* values;
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double* result=NULL;
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double min=1e13,max=-1e13,avg=0;
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codes_index* index;
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codes_handle* h=NULL;
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if (argc<2) return 1;
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/* create index of file contents for paramId and number */
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index = codes_index_new_from_file(0, argv[1], "paramId,number",&ret);
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CODES_CHECK(ret,0);
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/* get size of "paramId" list */
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CODES_CHECK(codes_index_get_size(index, "paramId", ¶mIdSize),0);
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printf("grib contains %lu different parameters\n",paramIdSize);
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/* allocate memory for "paramId" list */
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paramId = (char**) malloc(paramIdSize * sizeof(char*));
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/* get list of "paramId" */
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CODES_CHECK(codes_index_get_string(index, "paramId", paramId, ¶mIdSize),0);
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/* get size of ensemble number list */
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CODES_CHECK(codes_index_get_size(index, "number", &numberSize),0);
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printf("GRIB contains %lu different ensemble members\n",numberSize);
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/* allocate memory for ensemble number list */
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number = (long*) malloc(numberSize * sizeof(long));
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/* get list of ensemble numbers */
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CODES_CHECK(codes_index_get_long(index, "number", number, &numberSize),0);
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/* select T850 with paramId 130 */
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CODES_CHECK(codes_index_select_string(index, "paramId", "130"), 0);
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/* loop over all members */
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for (i = 0; i < numberSize; i++) {
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count++;
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/* select an individual ensemble number */
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CODES_CHECK(codes_index_select_long(index, "number", number[i]), 0);
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/* create handle for next GRIB message */
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h=codes_handle_new_from_index(index, &ret);
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if (ret) {
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printf("Error: %s\n", codes_get_error_message(ret));
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exit(ret);
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}
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/* get the size of the values array */
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CODES_CHECK(codes_get_size(h, "values", &values_len), 0);
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/* allocate memory for the GRIB message */
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values = (double*)malloc(values_len * sizeof(double));
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/* allocate memory for result */
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if ( i == 0 ) {
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result = (double *)calloc(values_len, sizeof(double));
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}
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/* get data values */
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CODES_CHECK(codes_get_double_array(h, "values", values, &values_len), 0);
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/* add up values */
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for (j = 0; j < values_len; j++)
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result[j] = result[j] + values[j];
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/* free memory and GRIB message handle */
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free(values);
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CODES_CHECK(codes_handle_delete(h), 0);
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}
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printf("We considered %d ensemble members\n", count);
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for (j = 0; j < values_len; j++)
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result[j] = result[j] / count;
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for (j = 0; j < values_len; j++) {
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if (min > result[j]) {
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min = result[j];
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}
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if (max < result[j]) {
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max = result[j];
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}
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avg += result[j];
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}
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avg = avg/values_len;
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printf("==============================================================================\n");
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printf("Stats for ensemble mean of T850\n");
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printf("Min: %f Max: %f Avg: %f\n",min,max,avg);
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printf("==============================================================================\n");
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/* finally free all other memory */
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for (i=0;i<paramIdSize;i++)
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free(paramId[i]);
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free(paramId);
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free(number);
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free(result);
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codes_index_delete(index);
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return 0;
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}
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