## Class BetweennessCentrality<V,​E>

• java.lang.Object
• org.jgrapht.alg.scoring.BetweennessCentrality<V,​E>
• Type Parameters:
V - the graph vertex type
E - the graph edge type
All Implemented Interfaces:
VertexScoringAlgorithm<V,​java.lang.Double>

public class BetweennessCentrality<V,​E>
extends java.lang.Object
implements VertexScoringAlgorithm<V,​java.lang.Double>
Betweenness centrality.

Computes the betweenness centrality of each vertex of a graph. The betweenness centrality of a node $v$ is given by the expression: $g(v)= \sum_{s \neq v \neq t}\frac{\sigma_{st}(v)}{\sigma_{st}}$ where $\sigma_{st}$ is the total number of shortest paths from node $s$ to node $t$ and $\sigma_{st}(v)$ is the number of those paths that pass through $v$. For more details see wikipedia. The algorithm is based on

• Brandes, Ulrik (2001). "A faster algorithm for betweenness centrality". Journal of Mathematical Sociology. 25 (2): 163–177.
The running time is $O(nm)$ and $O(nm +n^2 \log n)$ for unweighted and weighted graph respectively, where $n$ is the number of vertices and $m$ the number of edges of the graph. The space complexity is $O(n + m)$. Note that this running time assumes that arithmetic is performed between numbers whose representation needs a number of bits which is logarithmic in the instance size. There are instances where this is not true and path counters might grow super exponential. This class allows the user to adjust whether an exception is thrown in case overflow occurs. Default behavior is to ignore overflow issues.
Author:
Assaf Mizrachi
• ### Nested Class Summary

Nested Classes
Modifier and Type Class Description
static class  BetweennessCentrality.OverflowStrategy
Strategy followed when counting paths.
• ### Constructor Summary

Constructors
Constructor Description
BetweennessCentrality​(Graph<V,​E> graph)
Construct a new instance.
BetweennessCentrality​(Graph<V,​E> graph, boolean normalize)
Construct a new instance.
BetweennessCentrality​(Graph<V,​E> graph, boolean normalize, BetweennessCentrality.OverflowStrategy overflowStrategy)
Construct a new instance.
• ### Method Summary

All Methods
Modifier and Type Method Description
java.util.Map<V,​java.lang.Double> getScores()
Get a map with the scores of all vertices
java.lang.Double getVertexScore​(V v)
Get a vertex score
• ### Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
• ### Constructor Detail

• #### BetweennessCentrality

public BetweennessCentrality​(Graph<V,​E> graph)
Construct a new instance.
Parameters:
graph - the input graph
• #### BetweennessCentrality

public BetweennessCentrality​(Graph<V,​E> graph,
boolean normalize)
Construct a new instance.
Parameters:
graph - the input graph
normalize - whether to normalize by dividing the closeness by $(n-1) \cdot (n-2)$, where $n$ is the number of vertices of the graph
• #### BetweennessCentrality

public BetweennessCentrality​(Graph<V,​E> graph,
boolean normalize,
BetweennessCentrality.OverflowStrategy overflowStrategy)
Construct a new instance.
Parameters:
graph - the input graph
normalize - whether to normalize by dividing the closeness by $(n-1) \cdot (n-2)$, where $n$ is the number of vertices of the graph
overflowStrategy - strategy to use if overflow is detected
• ### Method Detail

• #### getScores

public java.util.Map<V,​java.lang.Double> getScores()
Get a map with the scores of all vertices
Specified by:
getScores in interface VertexScoringAlgorithm<V,​E>
Returns:
a map with all scores
• #### getVertexScore

public java.lang.Double getVertexScore​(V v)
Get a vertex score
Specified by:
getVertexScore in interface VertexScoringAlgorithm<V,​E>
Parameters:
v - the vertex
Returns:
the score