Class Subgraph<V,E,G extends Graph<V,E>>
- java.lang.Object
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- org.jgrapht.graph.AbstractGraph<V,E>
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- org.jgrapht.graph.Subgraph<V,E,G>
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- All Implemented Interfaces:
java.io.Serializable
,Graph<V,E>
- Direct Known Subclasses:
DirectedSubgraph
,UndirectedSubgraph
public class Subgraph<V,E,G extends Graph<V,E>> extends AbstractGraph<V,E> implements java.io.Serializable
A subgraph is a graph that has a subset of vertices and a subset of edges with respect to some base graph. More formally, a subgraph G(V,E) that is based on a base graph Gb(Vb,Eb) satisfies the following subgraph property: V is a subset of Vb and E is a subset of Eb. Other than this property, a subgraph is a graph with any respect and fully complies with theGraph
interface.If the base graph is a
ListenableGraph
, the subgraph listens on the base graph and guarantees the subgraph property. If an edge or a vertex is removed from the base graph, it is automatically removed from the subgraph. Subgraph listeners are informed on such removal only if it results in a cascaded removal from the subgraph. If the subgraph has been created as an induced subgraph it also keeps track of edges being added to its vertices. If vertices are added to the base graph, the subgraph remains unaffected.If the base graph is not a ListenableGraph, then the subgraph property cannot be guaranteed. If edges or vertices are removed from the base graph, they are not removed from the subgraph.
Modifications to Subgraph are allowed as long as the subgraph property is maintained. Addition of vertices or edges are allowed as long as they also exist in the base graph. Removal of vertices or edges is always allowed. The base graph is never affected by any modification made to the subgraph.
A subgraph may provide a "live-window" on a base graph, so that changes made to its vertices or edges are immediately reflected in the base graph, and vice versa. For that to happen, vertices and edges added to the subgraph must be identical (that is, reference-equal and not only value-equal) to their respective ones in the base graph. Previous versions of this class enforced such identity, at a severe performance cost. Currently it is no longer enforced. If you want to achieve a "live-window"functionality, your safest tactics would be to NOT override the
equals()
methods of your vertices and edges. If you use a class that has already overridden theequals()
method, such asString
, than you can use a wrapper around it, or else use it directly but exercise a great care to avoid having different-but-equal instances in the subgraph and the base graph.This graph implementation guarantees deterministic vertex and edge set ordering (via
LinkedHashSet
).- Since:
- Jul 18, 2003
- Author:
- Barak Naveh
- See Also:
Graph
,Set
, Serialized Form
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method 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.boolean
addVertex(V v)
Adds the specified vertex to this subgraph.boolean
containsEdge(E e)
Returns true if this graph contains the specified edge.boolean
containsVertex(V v)
Returns true if this graph contains the specified vertex.java.util.Set<E>
edgeSet()
Returns a set of the edges contained in this graph.java.util.Set<E>
edgesOf(V vertex)
Returns a set of all edges touching the specified vertex.java.util.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.G
getBase()
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.EdgeFactory<V,E>
getEdgeFactory()
Returns the edge factory using which this graph creates new edges.V
getEdgeSource(E e)
Returns the source vertex of an edge.V
getEdgeTarget(E e)
Returns the target vertex of an edge.double
getEdgeWeight(E e)
Returns the weight assigned to a given edge.boolean
removeEdge(E e)
Removes the specified edge from the graph.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.boolean
removeVertex(V v)
Removes the specified vertex from this graph including all its touching edges if present.void
setEdgeWeight(E e, double weight)
java.util.Set<V>
vertexSet()
Returns a set of the vertices contained in this graph.-
Methods inherited from class org.jgrapht.graph.AbstractGraph
assertVertexExist, containsEdge, removeAllEdges, removeAllEdges, removeAllEdges, removeAllVertices, toString, toStringFromSets
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Constructor Detail
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Subgraph
public Subgraph(G base, java.util.Set<V> vertexSubset, java.util.Set<E> edgeSubset)
Creates a new Subgraph.- Parameters:
base
- the base (backing) graph on which the subgraph will be based.vertexSubset
- vertices to include in the subgraph. Ifnull
then all vertices are included.edgeSubset
- edges to in include in the subgraph. Ifnull
then all the edges whose vertices found in the graph are included.
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Subgraph
public Subgraph(G base, java.util.Set<V> vertexSubset)
Creates a new induced Subgraph. The subgraph will keep track of edges being added to its vertex subset as well as deletion of edges and vertices. If base it not listenable, this is identical to the call Subgraph(base, vertexSubset, null) .- Parameters:
base
- the base (backing) graph on which the subgraph will be based.vertexSubset
- vertices to include in the subgraph. Ifnull
then all vertices are included.
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Method Detail
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getAllEdges
public java.util.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 isnull
, returnsnull
. 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 interfaceGraph<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)
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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 returnsnull
. If any of the specified vertices isnull
returnsnull
In undirected graphs, the returned edge may have its source and target vertices in the opposite order.
- Specified by:
getEdge
in interfaceGraph<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)
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getEdgeFactory
public EdgeFactory<V,E> getEdgeFactory()
Description copied from interface:Graph
Returns the edge factory using which this graph creates new edges. The edge factory is defined when the graph is constructed and must not be modified.- Specified by:
getEdgeFactory
in interfaceGraph<V,E>
- Returns:
- the edge factory using which this graph creates new edges.
- See Also:
Graph.getEdgeFactory()
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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 returnsnull
.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'sEdgeFactory
. For the new edge to be addede
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 edgee2
such thate2.equals(e)
. If suche2
is found then the newly created edgee
is abandoned, the method leaves this graph unchanged returnsnull
.- Specified by:
addEdge
in interfaceGraph<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)
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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 edgee2
such thate2.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 returnsfalse
. If the edge was added to the graph, returnstrue
.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 interfaceGraph<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)
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addVertex
public boolean addVertex(V v)
Adds the specified vertex to this subgraph.
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containsEdge
public boolean containsEdge(E e)
Description copied from interface:Graph
Returns true if this graph contains the specified edge. More formally, returns true if and only if this graph contains an edgee2
such thate.equals(e2)
. If the specified edge isnull
returnsfalse
.- Specified by:
containsEdge
in interfaceGraph<V,E>
- Parameters:
e
- edge whose presence in this graph is to be tested.- Returns:
- true if this graph contains the specified edge.
- See Also:
Graph.containsEdge(Object)
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containsVertex
public boolean containsVertex(V v)
Description copied from interface:Graph
Returns true if this graph contains the specified vertex. More formally, returns true if and only if this graph contains a vertexu
such thatu.equals(v)
. If the specified vertex isnull
returnsfalse
.- Specified by:
containsVertex
in interfaceGraph<V,E>
- Parameters:
v
- vertex whose presence in this graph is to be tested.- Returns:
- true if this graph contains the specified vertex.
- See Also:
Graph.containsVertex(Object)
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edgeSet
public java.util.Set<E> edgeSet()
Description copied from interface:Graph
Returns a set of the edges contained in this graph. The set is backed by the graph, so changes to the graph are reflected in the set. If the graph is modified while an iteration over the set is in progress, the results of the iteration are undefined.The graph implementation may maintain a particular set ordering (e.g. via
LinkedHashSet
) for deterministic iteration, but this is not required. It is the responsibility of callers who rely on this behavior to only use graph implementations which support it.- Specified by:
edgeSet
in interfaceGraph<V,E>
- Returns:
- a set of the edges contained in this graph.
- See Also:
Graph.edgeSet()
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edgesOf
public java.util.Set<E> edgesOf(V vertex)
Description copied from interface:Graph
Returns a set of all edges touching the specified vertex. If no edges are touching the specified vertex returns an empty set.- Specified by:
edgesOf
in interfaceGraph<V,E>
- Parameters:
vertex
- the vertex for which a set of touching edges is to be returned.- Returns:
- a set of all edges touching the specified vertex.
- See Also:
Graph.edgesOf(Object)
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removeEdge
public boolean removeEdge(E e)
Description copied from interface:Graph
Removes the specified edge from the graph. Removes the specified edge from this graph if it is present. More formally, removes an edgee2
such thate2.equals(e)
, if the graph contains such edge. Returns true if the graph contained the specified edge. (The graph will not contain the specified edge once the call returns).If the specified edge is
null
returnsfalse
.- Specified by:
removeEdge
in interfaceGraph<V,E>
- Parameters:
e
- edge to be removed from this graph, if present.- Returns:
true
if and only if the graph contained the specified edge.- See Also:
Graph.removeEdge(Object)
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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 ornull
otherwise.- Specified by:
removeEdge
in interfaceGraph<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)
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removeVertex
public boolean removeVertex(V v)
Description copied from interface:Graph
Removes the specified vertex from this graph including all its touching edges if present. More formally, if the graph contains a vertexu
such thatu.equals(v)
, the call removes all edges that touchu
and then removesu
itself. If no suchu
is found, the call leaves the graph unchanged. Returns true if the graph contained the specified vertex. (The graph will not contain the specified vertex once the call returns).If the specified vertex is
null
returnsfalse
.- Specified by:
removeVertex
in interfaceGraph<V,E>
- Parameters:
v
- vertex to be removed from this graph, if present.- Returns:
true
if the graph contained the specified vertex;false
otherwise.- See Also:
Graph.removeVertex(Object)
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vertexSet
public java.util.Set<V> vertexSet()
Description copied from interface:Graph
Returns a set of the vertices contained in this graph. The set is backed by the graph, so changes to the graph are reflected in the set. If the graph is modified while an iteration over the set is in progress, the results of the iteration are undefined.The graph implementation may maintain a particular set ordering (e.g. via
LinkedHashSet
) for deterministic iteration, but this is not required. It is the responsibility of callers who rely on this behavior to only use graph implementations which support it.- Specified by:
vertexSet
in interfaceGraph<V,E>
- Returns:
- a set view of the vertices contained in this graph.
- See Also:
Graph.vertexSet()
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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 interfaceGraph<V,E>
- Parameters:
e
- edge of interest- Returns:
- source vertex
- See Also:
Graph.getEdgeSource(Object)
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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 interfaceGraph<V,E>
- Parameters:
e
- edge of interest- Returns:
- target vertex
- See Also:
Graph.getEdgeTarget(Object)
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getBase
public G getBase()
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getEdgeWeight
public double getEdgeWeight(E e)
Description copied from interface:Graph
Returns the weight assigned to a given edge. Unweighted graphs return 1.0 (as defined byWeightedGraph.DEFAULT_EDGE_WEIGHT
), allowing weighted-graph algorithms to apply to them where meaningful.- Specified by:
getEdgeWeight
in interfaceGraph<V,E>
- Parameters:
e
- edge of interest- Returns:
- edge weight
- See Also:
Graph.getEdgeWeight(Object)
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setEdgeWeight
public void setEdgeWeight(E e, double weight)
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