On 11/08/08 17:02, Markus Neteler wrote:
On Mon, Aug 11, 2008 at 12:02 PM, G. Allegri <[EMAIL PROTECTED]> wrote:
Hi list.
I need to evaluate the shortest distance between the points of the same layer .
v.distance fails as to_map and from_map overlap (every shortest
distance is obviously 0: from point to itself). I was considering the
use of network analysis tools... but I don't see a straigthforward way
with them.
The best would be to have v.univar calculate these values.
Min and max algorithms are already built-in, it "just" needs
to be extended to consider not only attributes but also geometry.
(maybe with a flag to consider geometry instead of attributes?)
IIUC, Giovanni is not looking for one number, i.e. minimum of all the
distances between points in a map, but rather for the distance from each
point in a map to the closest other point in the same map. Please
correct me if I'm wrong.
The attached diff seems to work, but needs testing. I also filed this as
an enhancement wish in the tracker.
Moritz
Index: main.c
===================================================================
--- main.c (révision 32687)
+++ main.c (copie de travail)
@@ -78,12 +78,12 @@
struct GModule *module;
struct Option *from_opt, *to_opt, *from_type_opt, *to_type_opt,
*from_field_opt, *to_field_opt;
- struct Option *out_opt, *max_opt, *table_opt;
+ struct Option *out_opt, *max_opt, *min_opt, *table_opt;
struct Option *upload_opt, *column_opt, *to_column_opt;
struct Flag *print_flag, *all_flag;
struct Map_info From, To, Out, *Outp;
int from_type, to_type, from_field, to_field;
- double max;
+ double max, min;
struct line_pnts *FPoints, *TPoints;
struct line_cats *FCats, *TCats;
NEAR *Near, *near;
@@ -164,6 +164,13 @@
max_opt->answer = "-1";
max_opt->description = _("Maximum distance or -1 for no limit");
+ min_opt = G_define_option();
+ min_opt->key = "dmin";
+ min_opt->type = TYPE_DOUBLE;
+ min_opt->required = NO;
+ min_opt->answer = "-1";
+ min_opt->description = _("Minimum distance or -1 for no limit");
+
upload_opt = G_define_option();
upload_opt->key = "upload";
upload_opt->type = TYPE_STRING;
@@ -230,6 +237,7 @@
to_field = atoi(to_field_opt->answer);
max = atof(max_opt->answer);
+ min = atof(min_opt->answer);
if (all_flag->answer)
all = 1;
@@ -543,7 +551,7 @@
Vect_point_on_line(TPoints, tmp_talong, NULL, NULL, NULL,
&tmp_tangle, NULL);
- if (tmp_dist > max)
+ if (tmp_dist > max || tmp_dist < min)
continue; /* not in threshold */
/* TODO: more cats of the same field */
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