NAME
v.net.components - Computes strongly and weakly connected components in the network.
KEYWORDS
vector, network, components
SYNOPSIS
v.net.components
v.net.components help
v.net.components [-a] input=name alayer=string nlayer=string [afcolumn=name] [abcolumn=name] [ncolumn=string] output=name method=string [--overwrite] [--verbose] [--quiet]
Flags:
- -a
- Add points on nodes
- --overwrite
- Allow output files to overwrite existing files
- --verbose
- Verbose module output
- --quiet
- Quiet module output
Parameters:
- input=name [required]
- Name of input vector map
- Or data source for direct OGR access
- alayer=string [required]
- Layer number or name
- Arc layer
- Default: 1
- nlayer=string [required]
- Layer number or name
- Node layer
- Default: 2
- afcolumn=name
- Arc forward/both direction(s) cost column (number)
- abcolumn=name
- Arc backward direction cost column (number)
- ncolumn=string
- Node cost column (number)
- output=name [required]
- Name for output vector map
- method=string [required]
- Type of components
- Options: weak, strong
- weak: Weakly connected components
- strong: Strongly connected components
DESCRIPTION
v.net.components computes the weakly and strongly connected
components in a network.
NOTES
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.
v.net.components 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.
EXAMPLES
Any road network should form a single strongly connected component.
Otherwise, it is impossible to travel between some places.
v.net.components input=roads output=roads_components method=strong
SEE ALSO
v.category,
AUTHORS
Daniel Bundala, Google Summer of Code 2009, Student
Wolf Bergenheim, Mentor
Last changed: $Date: 2011-11-08 13:24:20 -0800 (Tue, 08 Nov 2011) $
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