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
[
layer=
integer]
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
-
Name of input 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
- output=name
-
Name for output vector map
- method=string
-
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.net, v.category,
AUTHORS¶
Daniel Bundala, Google Summer of Code 2009, Student
Wolf Bergenheim, Mentor
Last changed: $Date: 2013-05-23 22:01:55 +0200 (Thu, 23 May 2013) $
Full index
© 2003-2014 GRASS Development Team
