v.net.centrality(1grass) GRASS GIS User's Manual v.net.centrality(1grass)
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] [eigenvec-
tor=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 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
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
DESCRIPTION
v.net.centrality computes degree, closeness, betweenness and eigenvec-
tor 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 cre-
ated 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 param-
eters. 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 suc-
cessive 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
SOURCE CODE
Available at: v.net.centrality source code (history)
Accessed: unknown
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