org.jgrapht.graph

Class EdgeReversedGraph<V,E>

java.lang.Object

org.jgrapht.graph.AbstractGraph<V,E>

org.jgrapht.graph.GraphDelegator<V,E>

org.jgrapht.graph.EdgeReversedGraph<V,E>

All Implemented Interfaces:

Serializable, DirectedGraph<V,E>, Graph<V,E>

public class EdgeReversedGraph<V,E>
extends GraphDelegator<V,E>
implements DirectedGraph<V,E>

Provides an edge-reversed view g' of a directed graph g. The vertex sets for the two graphs are the same, but g' contains an edge (v2, v1) iff g contains an edge (v1, v2). g' is backed by g, so changes to g are reflected in g', and vice versa.

This class allows you to use a directed graph algorithm in reverse. For example, suppose you have a directed graph representing a tree, with edges from parent to child, and you want to find all of the parents of a node. To do this, simply create an edge-reversed graph and pass that as input to DepthFirstIterator.

Author:

John V. Sichi

See Also:

AsUndirectedGraph, Serialized Form

Constructor Summary

Constructors

Constructor and Description
EdgeReversedGraph(DirectedGraph<V,E> g) Creates a new EdgeReversedGraph.

Method Summary

Methods

Modifier and Type	Method and Description
E	addEdge(V sourceVertex, V targetVertex) Creates a new edge in this graph, going from the source vertex to the target vertex, and returns the created edge.
boolean	addEdge(V sourceVertex, V targetVertex, E e) Adds the specified edge to this graph, going from the source vertex to the target vertex.
Set<E>	getAllEdges(V sourceVertex, V targetVertex) Returns a set of all edges connecting source vertex to target vertex if such vertices exist in this graph.
E	getEdge(V sourceVertex, V targetVertex) Returns an edge connecting source vertex to target vertex if such vertices and such edge exist in this graph.
V	getEdgeSource(E e) Returns the source vertex of an edge.
V	getEdgeTarget(E e) Returns the target vertex of an edge.
Set<E>	incomingEdgesOf(V vertex) Returns a set of all edges incoming into the specified vertex.
int	inDegreeOf(V vertex) Returns the "in degree" of the specified vertex.
int	outDegreeOf(V vertex) Returns the "out degree" of the specified vertex.
Set<E>	outgoingEdgesOf(V vertex) Returns a set of all edges outgoing from the specified vertex.
E	removeEdge(V sourceVertex, V targetVertex) Removes an edge going from source vertex to target vertex, if such vertices and such edge exist in this graph.
String	toString() Returns a string of the parenthesized pair (V, E) representing this G=(V,E) graph.

Methods inherited from class org.jgrapht.graph.GraphDelegator

addVertex, containsEdge, containsVertex, degreeOf, edgeSet, edgesOf, getEdgeFactory, getEdgeWeight, removeEdge, removeVertex, setEdgeWeight, vertexSet

Methods inherited from class org.jgrapht.graph.AbstractGraph

assertVertexExist, containsEdge, equals, hashCode, removeAllEdges, removeAllEdges, removeAllEdges, removeAllVertices, toStringFromSets

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.jgrapht.Graph

addVertex, containsEdge, containsEdge, containsVertex, edgeSet, edgesOf, getEdgeFactory, getEdgeWeight, removeAllEdges, removeAllEdges, removeAllVertices, removeEdge, removeVertex, vertexSet

Constructor Detail

EdgeReversedGraph

public EdgeReversedGraph(DirectedGraph<V,E> g)

Creates a new EdgeReversedGraph.

Parameters:

g - the base (backing) graph on which the edge-reversed view will be based.

Method Detail

getEdge

public E getEdge(V sourceVertex,
        V targetVertex)

Description copied from interface: Graph

Returns an edge connecting source vertex to target vertex if such vertices and such edge exist in this graph. Otherwise returns null. If any of the specified vertices is null returns null

In undirected graphs, the returned edge may have its source and target vertices in the opposite order.

Specified by:

getEdge in interface Graph<V,E>

Overrides:

getEdge in class GraphDelegator<V,E>

Parameters:

sourceVertex - source vertex of the edge.

targetVertex - target vertex of the edge.

Returns:

an edge connecting source vertex to target vertex.

See Also:

Graph.getEdge(Object, Object)

getAllEdges

public Set<E> getAllEdges(V sourceVertex,
                 V targetVertex)

Description copied from interface: Graph

Returns a set of all edges connecting source vertex to target vertex if such vertices exist in this graph. If any of the vertices does not exist or is null, returns null. If both vertices exist but no edges found, returns an empty set.

In undirected graphs, some of the returned edges may have their source and target vertices in the opposite order. In simple graphs the returned set is either singleton set or empty set.

Specified by:

getAllEdges in interface Graph<V,E>

Overrides:

getAllEdges in class GraphDelegator<V,E>

Parameters:

sourceVertex - source vertex of the edge.

targetVertex - target vertex of the edge.

Returns:

a set of all edges connecting source vertex to target vertex.

See Also:

Graph.getAllEdges(Object, Object)

addEdge

public E addEdge(V sourceVertex,
        V targetVertex)

Description copied from interface: Graph

Creates a new edge in this graph, going from the source vertex to the target vertex, and returns the created edge. Some graphs do not allow edge-multiplicity. In such cases, if the graph already contains an edge from the specified source to the specified target, than this method does not change the graph and returns null.

The source and target vertices must already be contained in this graph. If they are not found in graph IllegalArgumentException is thrown.

This method creates the new edge e using this graph's EdgeFactory. For the new edge to be added e must not be equal to any other edge the graph (even if the graph allows edge-multiplicity). More formally, the graph must not contain any edge e2 such that e2.equals(e). If such e2 is found then the newly created edge e is abandoned, the method leaves this graph unchanged returns null.

Specified by:

addEdge in interface Graph<V,E>

Overrides:

addEdge in class GraphDelegator<V,E>

Parameters:

sourceVertex - source vertex of the edge.

targetVertex - target vertex of the edge.

Returns:

The newly created edge if added to the graph, otherwise null.

See Also:

Graph.addEdge(Object, Object)

addEdge

public boolean addEdge(V sourceVertex,
              V targetVertex,
              E e)

Description copied from interface: Graph

Adds the specified edge to this graph, going from the source vertex to the target vertex. More formally, adds the specified edge, e, to this graph if this graph contains no edge e2 such that e2.equals(e). If this graph already contains such an edge, the call leaves this graph unchanged and returns false. Some graphs do not allow edge-multiplicity. In such cases, if the graph already contains an edge from the specified source to the specified target, than this method does not change the graph and returns false. If the edge was added to the graph, returns true.

The source and target vertices must already be contained in this graph. If they are not found in graph IllegalArgumentException is thrown.

Specified by:

addEdge in interface Graph<V,E>

Overrides:

addEdge in class GraphDelegator<V,E>

Parameters:

sourceVertex - source vertex of the edge.

targetVertex - target vertex of the edge.

e - edge to be added to this graph.

Returns:

true if this graph did not already contain the specified edge.

See Also:

Graph.addEdge(Object, Object, Object)

inDegreeOf

public int inDegreeOf(V vertex)

Description copied from interface: DirectedGraph

Returns the "in degree" of the specified vertex. An in degree of a vertex in a directed graph is the number of inward directed edges from that vertex. See http://mathworld.wolfram.com/Indegree.html.

Specified by:

inDegreeOf in interface DirectedGraph<V,E>

Overrides:

inDegreeOf in class GraphDelegator<V,E>

Parameters:

vertex - vertex whose degree is to be calculated.

Returns:

the degree of the specified vertex.

See Also:

DirectedGraph.inDegreeOf(Object)

outDegreeOf

public int outDegreeOf(V vertex)

Description copied from interface: DirectedGraph

Returns the "out degree" of the specified vertex. An out degree of a vertex in a directed graph is the number of outward directed edges from that vertex. See http://mathworld.wolfram.com/Outdegree.html.

Specified by:

outDegreeOf in interface DirectedGraph<V,E>

Overrides:

outDegreeOf in class GraphDelegator<V,E>

Parameters:

vertex - vertex whose degree is to be calculated.

Returns:

the degree of the specified vertex.

See Also:

DirectedGraph.outDegreeOf(Object)

incomingEdgesOf

public Set<E> incomingEdgesOf(V vertex)

Description copied from interface: DirectedGraph

Returns a set of all edges incoming into the specified vertex.

Specified by:

incomingEdgesOf in interface DirectedGraph<V,E>

Overrides:

incomingEdgesOf in class GraphDelegator<V,E>

Parameters:

vertex - the vertex for which the list of incoming edges to be returned.

Returns:

a set of all edges incoming into the specified vertex.

See Also:

DirectedGraph.incomingEdgesOf(Object)

outgoingEdgesOf

public Set<E> outgoingEdgesOf(V vertex)

Description copied from interface: DirectedGraph

Returns a set of all edges outgoing from the specified vertex.

Specified by:

outgoingEdgesOf in interface DirectedGraph<V,E>

Overrides:

outgoingEdgesOf in class GraphDelegator<V,E>

Parameters:

vertex - the vertex for which the list of outgoing edges to be returned.

Returns:

a set of all edges outgoing from the specified vertex.

See Also:

DirectedGraph.outgoingEdgesOf(Object)

removeEdge

public E removeEdge(V sourceVertex,
           V targetVertex)

Description copied from interface: Graph

Removes an edge going from source vertex to target vertex, if such vertices and such edge exist in this graph. Returns the edge if removed or null otherwise.

Specified by:

removeEdge in interface Graph<V,E>

Overrides:

removeEdge in class GraphDelegator<V,E>

Parameters:

sourceVertex - source vertex of the edge.

targetVertex - target vertex of the edge.

Returns:

The removed edge, or null if no edge removed.

See Also:

Graph.removeEdge(Object, Object)

getEdgeSource

public V getEdgeSource(E e)

Description copied from interface: Graph

Returns the source vertex of an edge. For an undirected graph, source and target are distinguishable designations (but without any mathematical meaning).

Specified by:

getEdgeSource in interface Graph<V,E>

Overrides:

getEdgeSource in class GraphDelegator<V,E>

Parameters:

e - edge of interest

Returns:

source vertex

See Also:

Graph.getEdgeSource(Object)

getEdgeTarget

public V getEdgeTarget(E e)

Description copied from interface: Graph

Returns the target vertex of an edge. For an undirected graph, source and target are distinguishable designations (but without any mathematical meaning).

Specified by:

getEdgeTarget in interface Graph<V,E>

Overrides:

getEdgeTarget in class GraphDelegator<V,E>

Parameters:

e - edge of interest

Returns:

target vertex

See Also:

Graph.getEdgeTarget(Object)

toString

public String toString()

Description copied from class: AbstractGraph

Returns a string of the parenthesized pair (V, E) representing this G=(V,E) graph. 'V' is the string representation of the vertex set, and 'E' is the string representation of the edge set.

Overrides:

toString in class GraphDelegator<V,E>

Returns:

a string representation of this graph.

See Also:

Object.toString()