c_assign.c

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/*!
  \file cluster/c_assign.c
  
  \brief Cluster library - Assign cluster
  
  (C) 2001-2009 by the GRASS Development Team
  
  This program is free software under the GNU General Public License
  (>=v2). Read the file COPYING that comes with GRASS for details.
  
  \author Original author CERL
*/

#include <math.h>
#include <grass/cluster.h>

/*!
  \brief Assign cluster

  \param C pointer to Cluster structure
  \param interrupted ?
  
  \return -1 on interrupted
  \return 0 on success
*/
int I_cluster_assign(struct Cluster *C, int *interrupted)
{
    int p, c;
    int class, band;
    double d, q;
    double dmin;

    G_debug(3, "I_cluster_assign(npoints=%d,nclasses=%d,nbands=%d)",
            C->npoints, C->nclasses, C->nbands);
    
    for (p = 0; p < C->npoints; p++) {
        if (*interrupted)
            return -1;

        dmin = HUGE_VAL;
        class = 0;
        for (c = 0; c < C->nclasses; c++) {
            d = 0.0;
            for (band = 0; band < C->nbands; band++) {
                q = C->points[band][p];
                q -= C->mean[band][c];
                d += q * q;
            }
            if (c == 0 || d < dmin) {
                class = c;
                dmin = d;
            }
        }
        C->class[p] = class;
        C->count[class]++;
        for (band = 0; band < C->nbands; band++)
            C->sum[band][class] += C->points[band][p];
    }

    return 0;
}