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v.net.allpairs(1) Grass User's Manual v.net.allpairs(1)

v.net.allpairs - Computes the shortest path between all pairs of nodes in the network.

vector, network, shortest path

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]

-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

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

v.net.path, v.net.distance

Daniel Bundala, Google Summer of Code 2009, Student
 
Wolf Bergenheim, Mentor
 
Markus Metz
Last changed: $Date: 2014-12-24 15:11:14 +0100 (Wed, 24 Dec 2014) $

Available at: v.net.allpairs source code (history)
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© 2003-2018 GRASS Development Team, GRASS GIS 7.4.3 Reference Manual
GRASS 7.4.3

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