v.net.components - Computes strongly and weakly connected components in the network.
vector, network, components
v.net.components [-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
v.net.components 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. Module 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 components. Otherwise,
it is impossible to travel between some places.
v.net.components input=roads output=roads_components method=strong
Daniel Bundala, Google Summer of Code 2009, Student
Wolf Bergenheim, Mentor
Last changed: $Date: 2011-11-08 01:42:51 -0800 (Tue, 08 Nov 2011) $
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