/*
 * histo.c - Distribution of Z values
 *
 * Written 2010 by Werner Almesberger
 * Copyright 2010 by Werner Almesberger
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */


#include "util.h"
#include "array.h"
#include "histo.h"


struct histo *make_histo(struct array *a)
{
	int i;
	struct histo *h;

	h = alloc_type(struct histo);
	h->n = a->max_z-a->min_z+1;
	h->b = alloc_size(h->n*sizeof(int));
	for (i = 0; i != h->n; i++)
		h->b[i] = 0;
	for (i = 0; i != (a->max_x-a->min_x+1)*(a->max_y-a->min_y+1); i++)
		if (a->data[i] != UNDEF)
			h->b[a->data[i]-a->min_z]++;
	return h;
}


void free_histo(struct histo *h)
{
	free(h);
}


int median(const struct histo *h)
{
	int tot = 0, sum = 0;
	int i;

	for (i = 0; i != h->n; i++)
		tot += h->b[i];
	for (i = 0; sum < tot/2; i++)
		sum += h->b[i];
	return i-1;
}