org.jgrapht.graph

Class AsUndirectedGraph<V,E>

java.lang.Object

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

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

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

All Implemented Interfaces:

Serializable, Graph<V,E>, UndirectedGraph<V,E>

public class AsUndirectedGraph<V,E>
extends GraphDelegator<V,E>
implements Serializable, UndirectedGraph<V,E>

An undirected view of the backing directed graph specified in the constructor. This graph allows modules to apply algorithms designed for undirected graphs to a directed graph by simply ignoring edge direction. If the backing directed graph is an oriented graph, then the view will be a simple graph; otherwise, it will be a multigraph. Query operations on this graph "read through" to the backing graph. Attempts to add edges will result in an UnsupportedOperationException, but vertex addition/removal and edge removal are all supported (and immediately reflected in the backing graph).

Note that edges returned by this graph's accessors are really just the edges of the underlying directed graph. Since there is no interface distinction between directed and undirected edges, this detail should be irrelevant to algorithms.

This graph does not pass the hashCode and equals operations through to the backing graph, but relies on Object's equals and hashCode methods. This graph will be serializable if the backing graph is serializable.

Since:

Aug 14, 2003

Author:

John V. Sichi

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
AsUndirectedGraph(DirectedGraph<V,E> g) Constructor for AsUndirectedGraph.

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.
int	degreeOf(V vertex) Returns the degree of the specified 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.
Set<E>	incomingEdgesOf(V vertex)
int	inDegreeOf(V vertex)
int	outDegreeOf(V vertex)
Set<E>	outgoingEdgesOf(V vertex)
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, edgeSet, edgesOf, getEdgeFactory, getEdgeSource, getEdgeTarget, getEdgeWeight, removeEdge, 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, getEdgeSource, getEdgeTarget, getEdgeWeight, removeAllEdges, removeAllEdges, removeAllVertices, removeEdge, removeEdge, removeVertex, vertexSet

Constructor Detail

AsUndirectedGraph

public AsUndirectedGraph(DirectedGraph<V,E> g)

Constructor for AsUndirectedGraph.

Parameters:

g - the backing directed graph over which an undirected view is to be created.

Method Detail

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)

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)

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)

degreeOf

public int degreeOf(V vertex)

Description copied from interface: UndirectedGraph

Returns the degree of the specified vertex. A degree of a vertex in an undirected graph is the number of edges touching that vertex.

Specified by:

degreeOf in interface UndirectedGraph<V,E>

Overrides:

degreeOf in class GraphDelegator<V,E>

Parameters:

vertex - vertex whose degree is to be calculated.

Returns:

the degree of the specified vertex.

See Also:

UndirectedGraph.degreeOf(Object)

inDegreeOf

public int inDegreeOf(V vertex)

Overrides:

inDegreeOf in class GraphDelegator<V,E>

See Also:

DirectedGraph.inDegreeOf(Object)

incomingEdgesOf

public Set<E> incomingEdgesOf(V vertex)

Overrides:

incomingEdgesOf in class GraphDelegator<V,E>

See Also:

DirectedGraph.incomingEdgesOf(Object)

outDegreeOf

public int outDegreeOf(V vertex)

Overrides:

outDegreeOf in class GraphDelegator<V,E>

See Also:

DirectedGraph.outDegreeOf(Object)

outgoingEdgesOf

public Set<E> outgoingEdgesOf(V vertex)

Overrides:

outgoingEdgesOf in class GraphDelegator<V,E>

See Also:

DirectedGraph.outgoingEdgesOf(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:

AbstractGraph.toString()