v.net.allpairs(1grass)

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 projects

--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)

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

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

SEE ALSO
v.net.path, v.net.distance

AUTHORS
Daniel Bundala, Google Summer of Code 2009, Student
Wolf Bergenheim, Mentor
Markus Metz

SOURCE CODE

Available at: v.net.allpairs source code (history)

Accessed: Friday Apr 04 01:20:24 2025

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