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/****************************************************************************
*
* MODULE: r.buffer
*
* AUTHOR(S): Michael Shapiro - CERL
*
* PURPOSE: This program creates distance zones from non-zero
* cells in a grid layer. Distances are specified in
* meters (on the command-line). Window does not have to
* have square cells. Works both for planimetric
* (UTM, State Plane) and lat-long.
*
* COPYRIGHT: (C) 2005 by the GRASS Development Team
*
* This program is free software under the GNU General Public
* License (>=v2). Read the file COPYING that comes with GRASS
* for details.
*
****************************************************************************/
#include <stdlib.h>
#include "distance.h"
#include <grass/glocale.h>
static int cmp(const void *, const void *);
static int scan_dist(char *, double *);
int parse_distances(char **zone_list, double to_meters)
{
double dist;
double ew2 = 0.0;
int i;
int count;
for (count = 0; zone_list[count]; count++)
;
if (count <= 0)
return 0;
/* create an array to hold the distances */
distances = (struct Distance *)G_calloc(count, sizeof(struct Distance));
/* scan the command line for the distances */
if (window.proj != PROJECTION_LL) {
ew2 = window.ew_res * window.ew_res;
ns_to_ew_squared = window.ns_res * window.ns_res / ew2;
}
for (i = 0; i < count; i++) {
if (!scan_dist(zone_list[i], &dist)) {
G_warning(_("%s: %s - illegal distance specification"), pgm_name,
zone_list[i]);
return 0;
}
else {
dist *= (to_meters * meters_to_grid);
if (window.proj != PROJECTION_LL)
dist = dist * dist / ew2;
distances[i].dist = dist;
}
distances[i].label = zone_list[i];
}
/* sort the distances in increasing order */
qsort(distances, count, sizeof(struct Distance), cmp);
return count;
}
static int cmp(const void *aa, const void *bb)
{
const struct Distance *a = aa, *b = bb;
if (a->dist < b->dist)
return -1;
return a->dist > b->dist;
}
static int scan_dist(char *s, double *dist)
{
char dummy[2];
*dummy = 0;
if (sscanf(s, "%lf%1s", dist, dummy) != 1)
return 0;
if (*dummy)
return 0;
if (*dist <= 0.0)
return 0;
return 1;
}
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