clustering.c

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#include <math.h>

#include "csm_all.h"


/*
   A very very simple clustering algorithm.
   Try threshold = 5*sigma 
*/

void ld_simple_clustering(LDP ld, double threshold) {   
        int cluster = -1;
        double last_reading = 0; /* I have to initialize it 
          explicitely or else gcc complains it might be uninitialized.
          Stupid compiler, it cannot even solve the halting problem. */
        
        int i;
        for(i=0;i<ld->nrays;i++) {
                /* Skip if not valid */
                if(!ld_valid_ray(ld,i)) {
                        ld->cluster[i] = -1;
                        continue;
                }
                /* If this is the first valid point, assign cluster #0 */
                if(-1==cluster) 
                        cluster = 0;
                else 
                /* Else, start a new cluster if distance is above threshold */
                if( fabs(last_reading-ld->readings[i]) > threshold)
                        cluster++;
                                
                ld->cluster[i] = cluster;
                last_reading = ld->readings[i];
        }
        
        /* TODO: set to -1 the one-point clusters */
}