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v.net.components(1)	    GRASS GIS User's Manual	   v.net.components(1)

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	    [arc_layer=string]
       [node_layer=string]     [arc_column=name]    [arc_backward_column=name]
       [node_column=string]	output=name    method=string	 [--overwrite]
       [--help]	 [--verbose]  [--quiet]	 [--ui]

   Flags:
       -a
	   Add points on nodes

       --overwrite
	   Allow output	files to overwrite existing files

       --help
	   Print usage summary

       --verbose
	   Verbose module output

       --quiet
	   Quiet module	output

       --ui
	   Force launching GUI dialog

   Parameters:
       input=nameA [required]
	   Name	of input vector	map
	   Or data source for direct OGR access

       arc_layer=string
	   Arc layer
	   Vector  features can	have category values in	different layers. This
	   number determines which layer to use. When used with	direct OGR ac-
	   cess	this is	the layer name.
	   Default: 1

       node_layer=string
	   Node	layer
	   Vector  features can	have category values in	different layers. This
	   number determines which layer to use. When used with	direct OGR ac-
	   cess	this is	the layer name.
	   Default: 2

       arc_column=name
	   Arc forward/both direction(s) cost column (number)

       arc_backward_column=name
	   Arc backward	direction cost column (number)

       node_column=string
	   Node	cost column (number)

       output=nameA [required]
	   Name	for output vector map

       method=stringA [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	edge directions, there
       is a path between them.

       The  type of components is specified by method parameter.  v.net.compo-
       nents creates a table and links it to layer 1. 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.

       One-way roads can be defined by assigning a cost	of -1 to the appropri-
       ate  cost column	(arc_column or arc_backward_column). This affects only
       strongly	connected components. Network nodes can	be closed by assigning
       a cost of -1 to the node	cost column. All nodes with a cost < 0 can not
       be traversed and	are end	points,	while all nodes	with a cost aY	0  can
       be  traversed.	This affects both weakly and strongly connected	compo-
       nents.

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
       Markus Metz

SOURCE CODE
       Available at: v.net.components source code (history)

       Main  index  | Vector index | Topics index | Keywords index | Graphical
       index | Full index

       A(C) 2003-2020 GRASS Development	Team, GRASS GIS	7.8.3 Reference	Manual

GRASS 7.8.3						   v.net.components(1)

NAME | KEYWORDS | SYNOPSIS | DESCRIPTION | NOTES | EXAMPLES | SEE ALSO | AUTHORS | SOURCE CODE

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