 
NAME
v.net.allpairs  - Computes the shortest path between all pairs of nodes in the network.
KEYWORDS
vector, 
network, 
shortest path
SYNOPSIS
v.net.allpairs
v.net.allpairs --help
v.net.allpairs [-g] input=name output=name  [arc_layer=string]   [node_layer=string]   [cats=range]   [where=sql_query]   [arc_column=name]   [arc_backward_column=name]   [node_column=string]   [--overwrite]  [--help]  [--verbose]  [--quiet]  [--ui] 
Flags:
- -g
- Use geodesic calculation for longitude-latitude locations
- --overwrite
- Allow output files to overwrite existing files
- --help
- Print usage summary
- --verbose
- Verbose module output
- --quiet
- Quiet module output
- --ui
- Force launching GUI dialog
 
Parameters:
- input=name [required]
- Name of input vector map
- Or data source for direct OGR access
- output=name [required]
- Name for output vector map
- arc_layer=string
- Arc layer
- Vector features can have category values in different layers. This number determines which layer to use. When used with direct OGR access this is the layer name.
- Default: 1
- node_layer=string
- Node layer
- Vector features can have category values in different layers. This number determines which layer to use. When used with direct OGR access this is the layer name.
- Default: 2
- cats=range
- Category values
- Example: 1,3,7-9,13
- where=sql_query
- WHERE conditions of SQL statement without 'where' keyword
- Example: income < 1000 and population >= 10000
- arc_column=name
- Arc forward/both direction(s) cost column (number)
- arc_backward_column=name
- Arc backward direction cost column (number)
- node_column=string
- Node cost column (number)
 
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. 
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.
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
Result in matrix form:
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
Daniel Bundala, Google Summer of Code 2009, Student
Wolf Bergenheim, Mentor
Markus Metz
SOURCE CODE
  Available at:
  v.net.allpairs source code
  (history)
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GRASS Development Team,
GRASS GIS 7.9.dev Reference Manual