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NAME - Computes strongly and weakly connected components in the network.


vector, network, components

SYNOPSIS help [-a] input=name [layer=integer] output=name method=string [--overwrite] [--verbose] [--quiet]


Add points on nodes
Allow output files to overwrite existing files
Verbose module output
Quiet module output


Name of input vector map
Layer number
A single vector map can be connected to multiple database tables. This number determines which table to use.
Default: 1
Name for output vector map
Type of components
Options: weak,strong
weak: Weakly connected components
strong: Strongly connected components

DESCRIPTION computes the weakly and strongly connected components in a network.


Two nodes, u and v are in the same strongly connected component if there are directed paths from u to v and from v to u. The nodes are in the same weakly connected component if, ignoring orientation of the edges, there is a path between them.
The type of components is specified by method parameter. creates a table and links it to the given layer. This table contains only two integer columns: cat and comp . If a point or both endpoints of a line belong to the same component then the point/line is written to the output map and appropriate information is stored in the table. If -a flag is set then new points are added on the nodes without points. These points have category numbers larger than any category used in the input map.


Any road network should form a single strongly connected component. Otherwise, it is impossible to travel between some places. input=roads output=roads_components method=strong

SEE ALSO, v.category,


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

Last changed: $Date: 2013-05-23 13:01:55 -0700 (Thu, 23 May 2013) $

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