[GRASSLIST:596] How to program a little script

Hi folks,
I have to program a little script that, starting from 2 points (A and B) on a raster map (a DEM), calculate first 3 shortest going-down paths (from A to B).
It seems to be easy, but this is the first time i try to program GRASS and I don't know how to proceed.
Thank you,
Antonio Giglio.

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Hi,
first I suggest to look at alerady existing GRASS modules.

If already existing path calculation modules is not an option for You:
First You will need an algorithm how to travel from cell to cell and
calculate path length. I suggest to look at A*
(http://en.wikipedia.org/wiki/A-star_search_algorithm). It's quite
simple.
Second You ahve to read r.mapcalc man page to see how this algorithm
can be implemented. Actualy coding it in C for GRASS is peace of cake,
if You can do same with shell and mapcalc.

wbr,
Maris.

On 4/6/06, giglio.antonio@katamail.com <giglio.antonio@katamail.com> wrote:

Hi folks,
I have to program a little script that, starting from 2 points (A and B) on
a raster map (a DEM), calculate first 3 shortest going-down paths (from A to
B).
It seems to be easy, but this is the first time i try to program GRASS and I
don't know how to proceed.
Thank you,
Antonio Giglio.

________________________________________________________________________
SERVIZIO VOICE: TELEFONA e INVIA SMS dal tuo computer a tariffe vantaggiose!
Scopri come telefonare e videochiamare gratis da pc a pc.
http://voice.repubblica.it

I have to program a little script that, starting from 2 points (A and
B) on a raster map (a DEM), calculate first 3 shortest going-down
paths (from A to B). It seems to be easy, but this is the first time i
try to program GRASS and I don't know how to proceed.

see r.cost, r.walk

Hamish