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#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include <unistd.h>
#include <grass/gis.h>
#include <grass/raster.h>
#include <grass/glocale.h>
#include "method.h"
#define MEM 1024
/* function prototypes */
static int s_dev(double *, int, double *);
int o_sdev(const char *basemap, const char *covermap, const char *outputmap,
int usecats, struct Categories *cats)
{
struct Popen stats_child, reclass_child;
FILE *stats, *reclass;
int first, i, count;
size_t mem;
long basecat, covercat, catb, catc;
double value, sdev, x;
double *tab;
mem = MEM * sizeof(double);
tab = (double *)G_malloc(mem);
stats = run_stats(&stats_child, basemap, covermap, "-cn");
reclass = run_reclass(&reclass_child, basemap, outputmap);
first = 1;
while (read_stats(stats, &basecat, &covercat, &value)) {
if (first) {
first = 0;
catb = basecat;
catc = covercat;
i = 0;
count = 0;
}
if (basecat != catb) {
s_dev(tab, count, &sdev);
fprintf(reclass, "%ld = %ld %f\n", catb, catb, sdev);
catb = basecat;
catc = covercat;
count = 0;
}
if (usecats)
sscanf(Rast_get_c_cat((CELL *)&covercat, cats), "%lf", &x);
else
x = covercat;
for (i = 0; i < value; i++) {
if (count * sizeof(double) >= mem) {
mem += MEM * sizeof(double);
tab = (double *)G_realloc(tab, mem);
/* fprintf(stderr,"MALLOC: %d KB needed\n",(int)(mem/1024)); */
}
tab[count++] = x;
}
}
if (first) {
catb = catc = 0;
}
s_dev(tab, count, &sdev);
fprintf(reclass, "%ld = %ld %f\n", catb, catb, sdev);
G_debug(5, "%ld = %ld %f\n", catb, catb, sdev);
G_popen_close(&stats_child);
G_popen_close(&reclass_child);
return 0;
}
/***********************************************************************
*
* Given an array of data[1...n], this routine returns its standard
* deviation sdev.
*
************************************************************************/
static int s_dev(double *data, int n, double *sdev)
{
double ave, var, ep, s;
int i;
if (n < 1) {
G_warning(_("o_var: No data in array"));
return (1);
}
*sdev = 0.0;
var = 0.0;
ep = 0.0;
s = 0.0;
for (i = 0; i < n; i++) /* First pass to get the mean */
s += data[i];
ave = s / n;
for (i = 0; i < n; i++) {
s = data[i] - ave;
var += s * s;
ep += s;
}
var = (var - ep * ep / n) / (n - 1);
*sdev = sqrt(var);
return (0);
}
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