c_mode.c

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#include <grass/gis.h>
#include <grass/raster.h>
#include <grass/stats.h>
 
void c_mode(DCELL *result, DCELL *values, int n, const void *closure UNUSED)
{
    DCELL mode;
    int max;
    DCELL prev;
    int count;
    int i;
 
    n = sort_cell(values, n);
 
    max = 0;
    count = 0;
 
    for (i = 0; i < n; i++) {
        if (max == 0 || values[i] != prev) {
            prev = values[i];
            count = 0;
        }
 
        count++;
 
        if (count > max) {
            max = count;
            mode = prev;
        }
    }
 
    if (max == 0)
        Rast_set_d_null_value(result, 1);
    else
        *result = mode;
}
 
void w_mode(DCELL *result, DCELL (*values)[2], int n,
            const void *closure UNUSED)
{
    DCELL mode;
    DCELL max;
    DCELL prev;
    DCELL count;
    int i;
 
    n = sort_cell_w(values, n);
 
    max = 0.0;
    count = 0.0;
 
    for (i = 0; i < n; i++) {
        if (max == 0.0 || values[i][0] != prev) {
            prev = values[i][0];
            count = 0.0;
        }
 
        count += values[i][1];
 
        if (count > max) {
            max = count;
            mode = prev;
        }
    }
 
    if (max == 0.0)
        Rast_set_d_null_value(result, 1);
    else
        *result = mode;
}