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v.net.centrality(1) Grass User's Manual v.net.centrality(1)

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

vector, network, centrality measures

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]

-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

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 population >= 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

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

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 cumulative squared error between the successive iterations is less than error.

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

v.net, v.generalize

Daniel Bundala, Google Summer of Code 2009, Student
 
Wolf Bergenheim, Mentor
Last changed: $Date: 2016-03-28 23:23:39 +0200 (Mon, 28 Mar 2016) $

Available at: v.net.centrality source code (history)
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© 2003-2018 GRASS Development Team, GRASS GIS 7.4.3 Reference Manual
GRASS 7.4.3

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