[GRASS-user] shortest distance between 2 segments?

[A Horacio Samaniego]

I have a question on the network functionality on GRASS

Is there any way to query the shortest path between two vector segments in 
GRASS?

I have the following 2 segments in the DB

[local] roads=# select 
cat,fename,fetype,fraddl,fraddr,toaddl,toaddr,road_type from 
nm_bernalillo_alb where cat=18607 OR cat=12697;
   cat  | fename  | fetype | fraddl | fraddr | toaddl | toaddr | road_type
---------+------------+--------+--------+--------+--------+--------+-----------
12697 | Amherst | Dr       | 901    | 900    | 1013  | 1016  |      8
18607 | Monroe  | St        | 901    | 900    | 999    | 998    |       8
(2 rows)


I get the following output with no results because I believe you are 
required to specify points :

GRASS 6.0.0 (albers):~ > echo "1 18607 12697" | v.net.path 
input=nm_bernalillo_alb output=path2 afcolumn=road_type
Building graph:
Registering arcs ...  100%
Flattening the graph ... done.
Graph was built.
WARNING: No point with category 18607
WARNING: No point with category 12697
Attributes:
   cat  - path unique category assigned by module
   id   - path id (read from input)
   fcat - from point category
   tcat - to point category
   sp - result status:
        0 - OK, path found
        1 - node is not reachable
        2 - point of given category does not exist
   cost - travelling costs (on the network, not to/from network)
   fdist - the distance from first point to the network
   tdist - the distance from the network to second point
WARNING: 2 points of given category missing
Building topology ...
0 primitives registered
0 areas built
0 isles built
Attaching islands:
Attaching centroids: Topology was built.
Number of nodes     :   0
Number of primitives:   0
Number of points    :   0
Number of lines     :   0
Number of boundaries:   0
Number of centroids :   0
Number of areas     :   0
Number of isles     :   0


thanks!

H

Horacio Samaniego
Department of Biology
University of New Mexico
Albuquerque, NM. 87131
Phone:  (505) 277-3431
Fax:    (505) 277-0304

(http://www.unm.edu/~horacio)