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 [-ga] input=name output=name [ layer=integer] [cats=range] [ where=sql_query] [afcolumn=name] [abcolumn=name] [--overwrite] [-- verbose] [--quiet]

Flags:¶

-g

 

Use geodesic calculation for longitude-latitude locations

-a

 

Add points on nodes without points

--overwrite

 

Allow output files to overwrite existing files

--verbose

 

Verbose module output

--quiet

 

Quiet module output

Parameters:¶

input=name

 

Name of input vector map

output=name

 

Name for output vector map

layer=integer

 

Layer number

 

A single vector map can be connected to multiple database tables. This number determines which table to use.

 

Default: 1

cats=range

 

Category values

 

Example: 1,3,7-9,13

where=sql_query

 

WHERE conditions of SQL statement without 'where' keyword

 

Example: income = 10000

afcolumn=name

 

Name of arc forward/both direction(s) cost column

abcolumn=name

 

Name of arc backward direction cost column

DESCRIPTION¶

v.net.allpairs computes the shortest path between each select node and all other nodes.

NOTES¶

An attribute table is created and linked to layer. The table contains three columns: cat, to_cat, cost. Each entry denotes the cost of the shortest path from cat to to_cat. If the cost is negative then no path exists. If points are specified by cats, layer or where parameters then the table is filled only for the selected points. In other words, cat columns contains only selected points but the distances are computed and updated for all other nodes. If flag -a is set then new points are added on nodes without nodes. These points have the largest categorie. Precisely, category of each new point is larger than any of the old categories. If the flag is not set then no new points are created and hence the attribute table stores the costs only between the points already present in the input. Output consists of all points mentioned in either of the columns. If abcolumn is not given then then the same costs are used for forward and backward arcs.

EXAMPLES¶

Find shortest path from each intersection with pedestrian crossing to every other point using SHAPE_LEN for the cost of traversing the arcs in both directions. v.net.allpairs input=roads output=roads_pairs afcol=SHAPE_LEN where="crossing=1"

SEE ALSO¶

v.net.path, v.net.distance

AUTHORS¶

Daniel Bundala, Google Summer of Code 2009, Student Wolf Bergenheim, Mentor Last changed: $Date: 2011-11-08 10:42:51 +0100 (Tue, 08 Nov 2011) $ Full index © 2003-2011 GRASS Development Team