NAME

       v.net.centrality   -  Computes  degree,  centrality, betweeness, closeness and eigenvector
       centrality measures in the network.

KEYWORDS

       vector, network, centrality measures

SYNOPSIS

       v.net.centrality
       v.net.centrality --help
       v.net.centrality [-ga] input=name  [arc_layer=string]    [node_layer=string]   output=name
       [cats=range]      [where=sql_query]      [arc_column=name]      [arc_backward_column=name]
       [node_column=string]       [degree=name]        [closeness=name]        [betweenness=name]
       [eigenvector=name]     [iterations=integer]     [error=float]     [--overwrite]   [--help]
       [--verbose]  [--quiet]  [--ui]

   Flags:
       -g
           Use geodesic calculation for longitude-latitude locations

       -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

       output=name [required]
           Name for output vector map

       cats=range
           Category values
           Example: 1,3,7-9,13

       where=sql_query
           WHERE conditions of SQL statement without ’where’ keyword
           Example: income < 1000 and inhab >= 10000

       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)

       degree=name
           Name of degree centrality column

       closeness=name
           Name of closeness centrality column

       betweenness=name
           Name of betweenness centrality column

       eigenvector=name
           Name of eigenvector centrality column

       iterations=integer
           Maximum number of iterations to compute eigenvector centrality
           Default: 1000

       error=float
           Cumulative error tolerance for eigenvector centrality
           Default: 0.1

DESCRIPTION

       v.net.centrality  computes  degree,  closeness,  betweenness  and  eigenvector  centrality
       measures.

NOTES

       The module computes various centrality measures for each node and stores them in the given
       columns of an attribute table, which is created and linked to  the  output  map.  For  the
       description of these, please check the following wikipedia article.  If the column name is
       not given for a measure then that measure is not computed. If -a flag is set  then  points
       are  added  on nodes without points. Also, the points for which the output is computed can
       be specified by cats, layer and where parameters. However, if any of these  parameters  is
       present then -a flag is ignored and no new points are added.
       Betweenness  measure  is  not normalised. In order to get the normalised values (between 0
       and 1), each number needs to be divided by N choose 2=N*(N-1)/2 where N is the  number  of
       nodes  in  the  connected  component. Computation of eigenvector measure terminates if the
       given number of iterations is  reached  or  the  cummulative  squared  error  between  the
       successive iterations is less than error.

EXAMPLES

       Compute  closeness  and  betweenness  centrality  measures for each node and produce a map
       containing not only points already present in the input map but a map with point on  every
       node.
       v.net.centrality input=roads output=roads_cent closeness=closeness \
             betweenness=betweenness -a

SEE ALSO

        v.net, v.generalize

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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