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=name [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 access 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 access 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=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.net, v.category,

AUTHORS

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

       Last changed: $Date: 2013-05-23 21:59:24 +0200 (Thu, 23 May 2013) $

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