extract_subdomain.c

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00001 /* ***************************************************** */
00002 /* Extract subdomain in a variable given latitudes and   */
00003 /* longitudes.                                           */
00004 /* extract_subdomain.c                                   */
00005 /* ***************************************************** */
00006 /* Author: Christian Page, CERFACS, Toulouse, France.    */
00007 /* ***************************************************** */
00012 /* LICENSE BEGIN
00013 
00014 Copyright Cerfacs (Christian Page) (2015)
00015 
00016 christian.page@cerfacs.fr
00017 
00018 This software is a computer program whose purpose is to downscale climate
00019 scenarios using a statistical methodology based on weather regimes.
00020 
00021 This software is governed by the CeCILL license under French law and
00022 abiding by the rules of distribution of free software. You can use, 
00023 modify and/ or redistribute the software under the terms of the CeCILL
00024 license as circulated by CEA, CNRS and INRIA at the following URL
00025 "http://www.cecill.info". 
00026 
00027 As a counterpart to the access to the source code and rights to copy,
00028 modify and redistribute granted by the license, users are provided only
00029 with a limited warranty and the software's author, the holder of the
00030 economic rights, and the successive licensors have only limited
00031 liability. 
00032 
00033 In this respect, the user's attention is drawn to the risks associated
00034 with loading, using, modifying and/or developing or reproducing the
00035 software by the user in light of its specific status of free software,
00036 that may mean that it is complicated to manipulate, and that also
00037 therefore means that it is reserved for developers and experienced
00038 professionals having in-depth computer knowledge. Users are therefore
00039 encouraged to load and test the software's suitability as regards their
00040 requirements in conditions enabling the security of their systems and/or 
00041 data to be ensured and, more generally, to use and operate it in the 
00042 same conditions as regards security. 
00043 
00044 The fact that you are presently reading this means that you have had
00045 knowledge of the CeCILL license and that you accept its terms.
00046 
00047 LICENSE END */
00048 
00049 
00050 
00051 
00052 
00053 
00054 
00055 #include <utils.h>
00056 
00058 void
00059 extract_subdomain(double **buf_sub, double **lon_sub, double **lat_sub, int *nlon_sub, int *nlat_sub, double *buf,
00060                   double *lon, double *lat, double minlon, double maxlon, double minlat, double maxlat,
00061                   int nlon, int nlat, int ndim) {
00080   /* Compute subdomain and apply to arrays */
00081   
00082   int i; /* Loop counter */
00083   int j; /* Loop counter */
00084   int t; /* Time loop counter */
00085   int ii; /* Subdomain loop counter */
00086   int jj; /* Subdomain loop counter */
00087   double curlon; /* Current longitude */
00088   double curlat; /* Current latitude */
00089 
00090   /* Initializing */
00091   *nlon_sub = *nlat_sub = 0;
00092 
00093   /* Count latitude dimension length */
00094   for (i=0; i<nlat; i++)
00095     if (lat[i*nlon] >= minlat && lat[i*nlon] <= maxlat)
00096       (*nlat_sub)++;
00097 
00098   /* Count longitude dimension length */
00099   /* Adjust to span -180 to +180 */
00100   for (i=0; i<nlon; i++) {
00101     if (lon[i] > 180.0)
00102       curlon = lon[i] - 360.0;
00103     else
00104       curlon = lon[i];
00105     if (curlon >= minlon && curlon <= maxlon)
00106       (*nlon_sub)++;
00107   }
00108 
00109   /* Allocate memory with dimension lengths */
00110   (*buf_sub) = (double *) malloc((*nlon_sub)*(*nlat_sub)*ndim * sizeof(double));
00111   if ((*buf_sub) == NULL) alloc_error(__FILE__, __LINE__);
00112   (*lon_sub) = (double *) malloc((*nlon_sub)*(*nlat_sub) * sizeof(double));
00113   if ((*lon_sub) == NULL) alloc_error(__FILE__, __LINE__);
00114   (*lat_sub) = (double *) malloc((*nlon_sub)*(*nlat_sub) * sizeof(double));
00115   if ((*lat_sub) == NULL) alloc_error(__FILE__, __LINE__);
00116 
00117   /* Loop over all gridpoints and construct new buffer array spanning only subdomain */
00118   ii = 0;
00119   jj = 0;
00120   /* Loop over latitudes */
00121   for (j=0; j<nlat; j++) {
00122     if (ii > 0)
00123       jj++;
00124     ii = 0;
00125     /* Loop over longitudes */
00126     for (i=0; i<nlon; i++) {
00127       /* Adjust longitude to span -180 to +180 */
00128       if (lon[i] > 180.0)
00129         curlon = lon[i] - 360.0;
00130       else
00131         curlon = lon[i+j*nlon];
00132       curlat = lat[i+j*nlon];
00133       /* Retrieve only gridpoints within bounds */
00134       if (curlon >= minlon && curlon <= maxlon && curlat >= minlat && curlat <= maxlat) {
00135         /* Loop over last dimension to assign all values for this gridpoint */
00136         for (t=0; t<ndim; t++)
00137           (*buf_sub)[ii+jj*(*nlon_sub)+t*(*nlon_sub)*(*nlat_sub)] = buf[i+j*nlon+t*nlon*nlat];
00138         /* Create also latitude and longitude arrays */
00139         (*lon_sub)[ii+jj*(*nlon_sub)] = lon[i+j*nlon];
00140         (*lat_sub)[ii+jj*(*nlon_sub)] = lat[i+j*nlon];
00141         ii++;
00142       }
00143     }
00144   }
00145 }

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