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xmode.c
Go to the documentation of this file.
#include <stdlib.h>
#include <stdbool.h>
#include <grass/gis.h>
#include <grass/raster.h>
#include <grass/calc.h>
/**********************************************************************
mode(x1,x2,..,xn)
return mode of arguments
**********************************************************************/
#define SIZE_THRESHOLD 32
static int dcmp(const void *aa, const void *bb)
{
const double *a = aa;
const double *b = bb;
if (*a < *b)
return -1;
if (*a > *b)
return 1;
return 0;
}
static double mode(double *value, int argc)
{
/* Nota:
* It might be safer for to return nan or inf in case the input is empty,
* but it is a misuse of the function, so the return value is sort of
* undefined in that case.
*/
double mode_v = 0.0;
int mode_n = 0;
int i;
qsort(value, argc, sizeof(double), dcmp);
for (i = 0; i < argc;) {
int n = 1;
double v = value[i];
for (i++; i < argc; i++) {
if (value[i] != v)
break;
n++;
}
if (n < mode_n)
continue;
mode_v = v;
mode_n = n;
}
return mode_v;
}
int f_mode(int argc, const int *argt, void **args)
{
double stack_value[SIZE_THRESHOLD];
double *value = stack_value;
bool use_heap = false;
int size = argc * sizeof(double);
int i, j;
if (argc < 1)
return E_ARG_LO;
for (i = 1; i <= argc; i++)
if (argt[i] != argt[0])
return E_ARG_TYPE;
if (argc > SIZE_THRESHOLD) {
value = G_malloc(size);
use_heap = true;
}
switch (argt[argc]) {
case CELL_TYPE: {
CELL *res = args[0];
CELL **argv = (CELL **)&args[1];
for (i = 0; i < columns; i++) {
int nv = 0;
for (j = 0; j < argc && !nv; j++) {
if (IS_NULL_C(&argv[j][i]))
nv = 1;
else
value[j] = (double)argv[j][i];
}
if (nv)
SET_NULL_C(&res[i]);
else
res[i] = (CELL)mode(value, argc);
}
if (use_heap) {
G_free(value);
}
return 0;
}
case FCELL_TYPE: {
FCELL *res = args[0];
FCELL **argv = (FCELL **)&args[1];
for (i = 0; i < columns; i++) {
int nv = 0;
for (j = 0; j < argc && !nv; j++) {
if (IS_NULL_F(&argv[j][i]))
nv = 1;
else
value[j] = (double)argv[j][i];
}
if (nv)
SET_NULL_F(&res[i]);
else
res[i] = (FCELL)mode(value, argc);
}
if (use_heap) {
G_free(value);
}
return 0;
}
case DCELL_TYPE: {
DCELL *res = args[0];
DCELL **argv = (DCELL **)&args[1];
for (i = 0; i < columns; i++) {
int nv = 0;
for (j = 0; j < argc && !nv; j++) {
if (IS_NULL_D(&argv[j][i]))
nv = 1;
else
value[j] = (double)argv[j][i];
}
if (nv)
SET_NULL_D(&res[i]);
else
res[i] = (DCELL)mode(value, argc);
}
if (use_heap) {
G_free(value);
}
return 0;
}
default:
if (use_heap) {
G_free(value);
}
return E_INV_TYPE;
}
}
G_free
void G_free(void *buf)
Free allocated memory.
Definition alloc.c:147
columns
int columns
Definition calc.c:11
b
double b
Definition driver/set_window.c:5
SIZE_THRESHOLD
#define SIZE_THRESHOLD
Definition xmedian.c:13
f_mode
int f_mode(int argc, const int *argt, void **args)
Definition xmode.c:60