DESCRIPTION
v.net.allpairs computes the shortest path between each selected 
node and all other selected nodes. The output is a vector with the 
selected nodes and the shortest paths. 
NOTES
An attribute table is created and linked to layer arc_layer. The 
table contains four columns: cat, from_cat, 
to_cat, cost. 
Each cat entry denotes the category of the shortest path from 
the node with category from_cat to the node with category 
to_cat. If points are specified by cats, layer or 
where parameters then the table is filled only for the selected 
points.
If arc_backward_column is not given then then the same costs are used for 
forward and backward arcs.
EXAMPLE
Find shortest path along roads from selected archsites (Spearfish sample 
dataset):
# prepare network: connect archsites to roads with threshold 200
v.net input=roads@PERMANENT points=archsites@PERMANENT \
output=roads_net operation=connect thresh=200
# verify result
v.category input=roads_net option=report
# only lines should have a category in layer 1
# only points should have a category in layer 2
# shortest path between all points with categories 1 - 5 in layer 2
v.net.allpairs input=roads_net cats=1-5 out=roads_net_all
v.db.select roads_net_all
from\to	1		3		4		5
1	0		18820.386	17206.651	17373.274
3	18820.386	0		1739.079	9040.575
4	17206.651	1739.079	0		7426.84
5	17373.274	9040.575	7426.84		0
SEE ALSO
v.net.path,
v.net.distance
AUTHORS
Daniel Bundala, Google Summer of Code 2009, Student
Wolf Bergenheim, Mentor
Markus Metz
Last changed: $Date: 2014-12-24 15:44:33 +0100 (Wed, 24 Dec 2014) $