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   [layer=integer]   output=name    [cats=range]     [where=sql_query]
       [afcolumn=name]       [abcolumn=name]       [degree=name]       [closeness=name]       [betweenness=name]
       [eigenvector=name]   [iterations=integer]   [error=float]   [--overwrite]  [--verbose]  [--quiet]

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

       -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

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

       where=sql_query
           WHERE conditions of SQL statement without 'where' keyword
           Example: income = 10000

       afcolumn=name
           Name of arc forward/both direction(s) cost column

       abcolumn=name
           Name of arc backward direction cost column

       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
           Cummulative 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 13:01:55 -0700 (Thu, 23 May 2013) $

       Full index

       © 2003-2013 GRASS Development Team

GRASS 6.4.3                                                                             v.net.centrality(1grass)