Class GoldbergMaximumDensitySubgraphAlgorithm<V,E>
- java.lang.Object
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- org.jgrapht.alg.densesubgraph.GoldbergMaximumDensitySubgraphAlgorithmBase<V,E>
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- org.jgrapht.alg.densesubgraph.GoldbergMaximumDensitySubgraphAlgorithm<V,E>
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- Type Parameters:
V
- Type of verticesE
- Type of edges
- All Implemented Interfaces:
MaximumDensitySubgraphAlgorithm<V,E>
public class GoldbergMaximumDensitySubgraphAlgorithm<V,E> extends GoldbergMaximumDensitySubgraphAlgorithmBase<V,E>
This class computes a maximum density subgraph based on the algorithm described by Andrew Vladislav Goldberg in Finding Maximum Density Subgraphs, 1984, University of Berkley.
The basic concept is to construct a network that can be used to compute the maximum density subgraph using a binary search approach. SeeGoldbergMaximumDensitySubgraphAlgorithmBase
for further detailsThis variant of the algorithm assumes the density of a positive real-weighted graph G=(V,E) to be defined as \[\frac{\sum\limits_{e \in E} w(e)}{\left|{V}\right|}\] and sets the weights of the network from
GoldbergMaximumDensitySubgraphAlgorithmBase
as proposed in the above paper. For this case the weights of the network must be chosen to be: \[c_{ij}=w(ij)\,\forall \{i,j\}\in E\] \[c_{it}=m+2g-d_i\,\forall i \in V\] \[c_{si}=m\,\forall i \in V\] where $m=\left|{E}\right|$ and $d_i$ is the degree of vertex $i$.
All the math to prove the correctness of these weights is the same as inGoldbergMaximumDensitySubgraphAlgorithmBase
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Because the density is per definition guaranteed to be rational, the distance of 2 possible solutions for the maximum density can't be smaller than $\frac{1}{W(W-1)}$. This means shrinking the binary search interval to this size, the correct solution is found. The runtime can in this case be given by $O(M(n,n+m)\log{W})$, where $M(n,m)$ is the runtime of the internally used
MinimumSTCutAlgorithm
and $W$ is the sum of all weights from $G$.- Author:
- Andre Immig
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Field Summary
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Fields inherited from class org.jgrapht.alg.densesubgraph.GoldbergMaximumDensitySubgraphAlgorithmBase
graph, guess
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Constructor Summary
Constructors Constructor Description GoldbergMaximumDensitySubgraphAlgorithm(Graph<V,E> graph, V s, V t, double epsilon)
Convenience constructor that uses PushRelabel as default MinimumSTCutAlgorithmGoldbergMaximumDensitySubgraphAlgorithm(Graph<V,E> graph, V s, V t, double epsilon, java.util.function.Function<Graph<V,DefaultWeightedEdge>,MinimumSTCutAlgorithm<V,DefaultWeightedEdge>> algFactory)
Constructor
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description protected double
computeDensityDenominator(Graph<V,E> g)
protected double
computeDensityNumerator(Graph<V,E> g)
protected double
getEdgeWeightFromSourceToVertex(V v)
Getter for network weights of edges su for u in Vprotected double
getEdgeWeightFromVertexToSink(V v)
Getter for network weights of edges ut for u in V-
Methods inherited from class org.jgrapht.alg.densesubgraph.GoldbergMaximumDensitySubgraphAlgorithmBase
calculateDensest, getDensity
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Constructor Detail
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GoldbergMaximumDensitySubgraphAlgorithm
public GoldbergMaximumDensitySubgraphAlgorithm(Graph<V,E> graph, V s, V t, double epsilon, java.util.function.Function<Graph<V,DefaultWeightedEdge>,MinimumSTCutAlgorithm<V,DefaultWeightedEdge>> algFactory)
Constructor- Parameters:
algFactory
- factory to construct the algorithm to usegraph
- input for computations
- additional source vertext
- additional target vertexepsilon
- to use for internal computation
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GoldbergMaximumDensitySubgraphAlgorithm
public GoldbergMaximumDensitySubgraphAlgorithm(Graph<V,E> graph, V s, V t, double epsilon)
Convenience constructor that uses PushRelabel as default MinimumSTCutAlgorithm- Parameters:
graph
- input for computations
- additional source vertext
- additional target vertexepsilon
- to use for internal computation
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Method Detail
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getEdgeWeightFromSourceToVertex
protected double getEdgeWeightFromSourceToVertex(V v)
Getter for network weights of edges su for u in V- Specified by:
getEdgeWeightFromSourceToVertex
in classGoldbergMaximumDensitySubgraphAlgorithmBase<V,E>
- Parameters:
v
- of V- Returns:
- weight of the edge
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getEdgeWeightFromVertexToSink
protected double getEdgeWeightFromVertexToSink(V v)
Getter for network weights of edges ut for u in V- Specified by:
getEdgeWeightFromVertexToSink
in classGoldbergMaximumDensitySubgraphAlgorithmBase<V,E>
- Parameters:
v
- of V- Returns:
- weight of the edge
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computeDensityNumerator
protected double computeDensityNumerator(Graph<V,E> g)
- Specified by:
computeDensityNumerator
in classGoldbergMaximumDensitySubgraphAlgorithmBase<V,E>
- Parameters:
g
- the graph to compute the numerator density from- Returns:
- numerator part of the density
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computeDensityDenominator
protected double computeDensityDenominator(Graph<V,E> g)
- Specified by:
computeDensityDenominator
in classGoldbergMaximumDensitySubgraphAlgorithmBase<V,E>
- Parameters:
g
- the graph to compute the denominator density from- Returns:
- numerator part of the density
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