edu.uci.ics.jung.graph
Interface Hypergraph<V,E>

All Known Subinterfaces:

DirectedGraph<V,E>, Forest<V,E>, Graph<V,E>, KPartiteGraph<V,E>, Tree<V,E>, UndirectedGraph<V,E>

All Known Implementing Classes:

AbstractGraph, AbstractTypedGraph, DelegateForest, DelegateTree, DirectedOrderedSparseMultigraph, DirectedSparseGraph, DirectedSparseMultigraph, GraphDecorator, ObservableGraph, OrderedKAryTree, OrderedSparseMultigraph, SetHypergraph, SortedSparseMultigraph, SparseGraph, SparseMultigraph, UndirectedOrderedSparseMultigraph, UndirectedSparseGraph, UndirectedSparseMultigraph

public interface Hypergraph<V,E>

A hypergraph, consisting of a set of vertices of type V and a set of hyperedges of type E which connect the vertices. This is the base interface for all JUNG graph types.

This interface permits, but does not enforce, any of the following common variations of graphs:

• hyperedges (edges which connect a set of vertices of any size)
• edges (these have have exactly two endpoints, which may or may not be distinct)
• self-loops (edges which connect exactly one vertex)
• directed and undirected edges
• vertices and edges with attributes (for example, weighted edges)
• vertices and edges with different constraints or properties (for example, bipartite or multimodal graphs)
• parallel edges (multiple edges which connect a single set of vertices)
• internal representations as matrices or as adjacency lists or adjacency maps

Extensions or implementations of this interface may enforce or disallow any or all of these variations.

Notes:

• The collections returned by Hypergraph instances should be treated in general as if read-only. While they are not contractually guaranteed (or required) to be immutable, this interface does not define the outcome if they are mutated. Mutations should be done via {add,remove}{Edge,Vertex}, or in the constructor.

Author:

Joshua O'Madadhain

Method Summary

boolean	addEdge(E edge, Collection<? extends V> vertices) Adds edge to this graph.
boolean	addEdge(E edge, Collection<? extends V> vertices, EdgeType edge_type) Adds edge to this graph with type edge_type.
boolean	addVertex(V vertex) Adds vertex to this graph.
boolean	containsEdge(E edge) Returns true if this graph's edge collection contains edge.
boolean	containsVertex(V vertex) Returns true if this graph's vertex collection contains vertex.
int	degree(V vertex) Returns the number of edges incident to vertex.
E	findEdge(V v1, V v2) Returns an edge that connects this vertex to v.
Collection<E>	findEdgeSet(V v1, V v2) Returns all edges that connects this vertex to v.
EdgeType	getDefaultEdgeType() Returns the default edge type for this graph.
V	getDest(E directed_edge) If directed_edge is a directed edge in this graph, returns the destination; otherwise returns null.
int	getEdgeCount() Returns the number of edges in this graph.
int	getEdgeCount(EdgeType edge_type) Returns the number of edges of type edge_type in this graph.
Collection<E>	getEdges() Returns a view of all edges in this graph.
Collection<E>	getEdges(EdgeType edge_type) Returns the collection of edges in this graph which are of type edge_type.
EdgeType	getEdgeType(E edge) Returns the edge type of edge in this graph.
int	getIncidentCount(E edge) Returns the number of vertices that are incident to edge.
Collection<E>	getIncidentEdges(V vertex) Returns the collection of edges in this graph which are connected to vertex.
Collection<V>	getIncidentVertices(E edge) Returns the collection of vertices in this graph which are connected to edge.
Collection<E>	getInEdges(V vertex) Returns a Collection view of the incoming edges incident to vertex in this graph.
int	getNeighborCount(V vertex) Returns the number of vertices that are adjacent to vertex (that is, the number of vertices that are incident to edges in vertex's incident edge set).
Collection<V>	getNeighbors(V vertex) Returns the collection of vertices which are connected to vertex via any edges in this graph.
Collection<E>	getOutEdges(V vertex) Returns a Collection view of the outgoing edges incident to vertex in this graph.
Collection<V>	getPredecessors(V vertex) Returns a Collection view of the predecessors of vertex in this graph.
V	getSource(E directed_edge) If directed_edge is a directed edge in this graph, returns the source; otherwise returns null.
Collection<V>	getSuccessors(V vertex) Returns a Collection view of the successors of vertex in this graph.
int	getVertexCount() Returns the number of vertices in this graph.
Collection<V>	getVertices() Returns a view of all vertices in this graph.
int	inDegree(V vertex) Returns the number of incoming edges incident to vertex.
boolean	isIncident(V vertex, E edge) Returns true if vertex and edge are incident to each other.
boolean	isNeighbor(V v1, V v2) Returns true if v1 and v2 share an incident edge.
int	outDegree(V vertex) Returns the number of outgoing edges incident to vertex.
boolean	removeEdge(E edge) Removes edge from this graph.
boolean	removeVertex(V vertex) Removes vertex from this graph.

Method Detail

getEdges

Collection<E> getEdges()

Returns a view of all edges in this graph. In general, this obeys the Collection contract, and therefore makes no guarantees about the ordering of the vertices within the set.

Returns:

a Collection view of all edges in this graph

getVertices

Collection<V> getVertices()

Returns a view of all vertices in this graph. In general, this obeys the Collection contract, and therefore makes no guarantees about the ordering of the vertices within the set.

Returns:

a Collection view of all vertices in this graph

containsVertex

boolean containsVertex(V vertex)

Returns true if this graph's vertex collection contains vertex. Equivalent to getVertices().contains(vertex).

Parameters:

vertex - the vertex whose presence is being queried

Returns:

true iff this graph contains a vertex vertex

containsEdge

boolean containsEdge(E edge)

Returns true if this graph's edge collection contains edge. Equivalent to getEdges().contains(edge).

Parameters:

edge - the edge whose presence is being queried

Returns:

true iff this graph contains an edge edge

getEdgeCount

int getEdgeCount()

Returns the number of edges in this graph.

Returns:

the number of edges in this graph

getVertexCount

int getVertexCount()

Returns the number of vertices in this graph.

Returns:

the number of vertices in this graph

getNeighbors

Collection<V> getNeighbors(V vertex)

Returns the collection of vertices which are connected to vertex via any edges in this graph. If vertex is connected to itself with a self-loop, then it will be included in the collection returned.

Parameters:

vertex - the vertex whose neighbors are to be returned

Returns:

the collection of vertices which are connected to vertex, or null if vertex is not present

getIncidentEdges

Collection<E> getIncidentEdges(V vertex)

Returns the collection of edges in this graph which are connected to vertex.

Parameters:

vertex - the vertex whose incident edges are to be returned

Returns:

the collection of edges which are connected to vertex, or null if vertex is not present

getIncidentVertices

Collection<V> getIncidentVertices(E edge)

Returns the collection of vertices in this graph which are connected to edge. Note that for some graph types there are guarantees about the size of this collection (i.e., some graphs contain edges that have exactly two endpoints, which may or may not be distinct). Implementations for those graph types may provide alternate methods that provide more convenient access to the vertices.

Parameters:

edge - the edge whose incident vertices are to be returned

Returns:

the collection of vertices which are connected to edge, or null if edge is not present

findEdge

E findEdge(V v1,
           V v2)

Returns an edge that connects this vertex to v. If this edge is not uniquely defined (that is, if the graph contains more than one edge connecting v1 to v2), any of these edges may be returned. findEdgeSet(v1, v2) may be used to return all such edges. Returns null if either of the following is true:

• v2 is not connected to v1
• either v1 or v2 are not present in this graph

Note: for purposes of this method, v1 is only considered to be connected to v2 via a given directed edge e if v1 == e.getSource() && v2 == e.getDest() evaluates to true. (v1 and v2 are connected by an undirected edge u if u is incident to both v1 and v2.)

Returns:

an edge that connects v1 to v2, or null if no such edge exists (or either vertex is not present)

See Also:

findEdgeSet(Object, Object)

findEdgeSet

Collection<E> findEdgeSet(V v1,
                          V v2)

Returns all edges that connects this vertex to v. If this edge is not uniquely defined (that is, if the graph contains more than one edge connecting v1 to v2), any of these edges may be returned. findEdgeSet(v1, v2) may be used to return all such edges. Returns null if v2 is not connected to v1.
Returns an empty collection if either v1 or v2 are not present in this graph.

Note: for purposes of this method, v1 is only considered to be connected to v2 via a given directed edge d if v1 == d.getSource() && v2 == d.getDest() evaluates to true. (v1 and v2 are connected by an undirected edge u if u is incident to both v1 and v2.)

Returns:

a collection containing all edges that connect v1 to v2, or null if either vertex is not present

See Also:

findEdge(Object, Object)

addVertex

boolean addVertex(V vertex)

Adds vertex to this graph. Fails if vertex is null or already in the graph.

Parameters:

vertex - the vertex to add

Returns:

true if the add is successful, and false otherwise

Throws:

IllegalArgumentException - if vertex is null

addEdge

boolean addEdge(E edge,
                Collection<? extends V> vertices)

Adds edge to this graph. Fails under the following circumstances:

• edge is already an element of the graph
• either edge or vertices is null
• vertices has the wrong number of vertices for the graph type
• vertices are already connected by another edge in this graph, and this graph does not accept parallel edges

Parameters:

edge -

vertices -

Returns:

true if the add is successful, and false otherwise

Throws:

IllegalArgumentException - if edge or vertices is null, or if a different vertex set in this graph is already connected by edge, or if vertices are not a legal vertex set for edge

addEdge

boolean addEdge(E edge,
                Collection<? extends V> vertices,
                EdgeType edge_type)

Adds edge to this graph with type edge_type. Fails under the following circumstances:

• edge is already an element of the graph
• either edge or vertices is null
• vertices has the wrong number of vertices for the graph type
• vertices are already connected by another edge in this graph, and this graph does not accept parallel edges
• edge_type is not legal for this graph

Parameters:

edge -

vertices -

Returns:

true if the add is successful, and false otherwise

Throws:

IllegalArgumentException - if edge or vertices is null, or if a different vertex set in this graph is already connected by edge, or if vertices are not a legal vertex set for edge

removeVertex

boolean removeVertex(V vertex)

Removes vertex from this graph. As a side effect, removes any edges e incident to vertex if the removal of vertex would cause e to be incident to an illegal number of vertices. (Thus, for example, incident hyperedges are not removed, but incident edges--which must be connected to a vertex at both endpoints--are removed.)

Fails under the following circumstances:

• vertex is not an element of this graph
• vertex is null

Parameters:

vertex - the vertex to remove

Returns:

true if the removal is successful, false otherwise

removeEdge

boolean removeEdge(E edge)

Removes edge from this graph. Fails if edge is null, or is otherwise not an element of this graph.

Parameters:

edge - the edge to remove

Returns:

true if the removal is successful, false otherwise

isNeighbor

boolean isNeighbor(V v1,
                   V v2)

Returns true if v1 and v2 share an incident edge. Equivalent to getNeighbors(v1).contains(v2).

Parameters:

v1 - the first vertex to test

v2 - the second vertex to test

Returns:

true if v1 and v2 share an incident edge

isIncident

boolean isIncident(V vertex,
                   E edge)

Returns true if vertex and edge are incident to each other. Equivalent to getIncidentEdges(vertex).contains(edge) and to getIncidentVertices(edge).contains(vertex).

Parameters:

vertex -

edge -

Returns:

true if vertex and edge are incident to each other

degree

int degree(V vertex)

Returns the number of edges incident to vertex. Special cases of interest:

• Incident self-loops are counted once.
• If there is only one edge that connects this vertex to each of its neighbors (and vice versa), then the value returned will also be equal to the number of neighbors that this vertex has (that is, the output of getNeighborCount).
• If the graph is directed, then the value returned will be the sum of this vertex's indegree (the number of edges whose destination is this vertex) and its outdegree (the number of edges whose source is this vertex), minus the number of incident self-loops (to avoid double-counting).

Equivalent to getIncidentEdges(vertex).size().

Parameters:

vertex - the vertex whose degree is to be returned

Returns:

the degree of this node

See Also:

getNeighborCount(Object)

getNeighborCount

int getNeighborCount(V vertex)

Returns the number of vertices that are adjacent to vertex (that is, the number of vertices that are incident to edges in vertex's incident edge set).

Equivalent to getNeighbors(vertex).size().

Parameters:

vertex - the vertex whose neighbor count is to be returned

Returns:

the number of neighboring vertices

getIncidentCount

int getIncidentCount(E edge)

Returns the number of vertices that are incident to edge. For hyperedges, this can be any nonnegative integer; for edges this must be 2 (or 1 if self-loops are permitted).

Equivalent to getIncidentVertices(edge).size().

Parameters:

edge - the edge whose incident vertex count is to be returned

Returns:

the number of vertices that are incident to edge.

getEdgeType

EdgeType getEdgeType(E edge)

Returns the edge type of edge in this graph.

Parameters:

edge -

Returns:

the EdgeType of edge, or null if edge has no defined type

getDefaultEdgeType

EdgeType getDefaultEdgeType()

Returns the default edge type for this graph.

Returns:

the default edge type for this graph

getEdges

Collection<E> getEdges(EdgeType edge_type)

Returns the collection of edges in this graph which are of type edge_type.

Parameters:

edge_type - the type of edges to be returned

Returns:

the collection of edges which are of type edge_type, or null if the graph does not accept edges of this type

See Also:

EdgeType

getEdgeCount

int getEdgeCount(EdgeType edge_type)

Returns the number of edges of type edge_type in this graph.

Parameters:

edge_type - the type of edge for which the count is to be returned

Returns:

the number of edges of type edge_type in this graph

getInEdges

Collection<E> getInEdges(V vertex)

Returns a Collection view of the incoming edges incident to vertex in this graph.

Parameters:

vertex - the vertex whose incoming edges are to be returned

Returns:

a Collection view of the incoming edges incident to vertex in this graph

getOutEdges

Collection<E> getOutEdges(V vertex)

Returns a Collection view of the outgoing edges incident to vertex in this graph.

Parameters:

vertex - the vertex whose outgoing edges are to be returned

Returns:

a Collection view of the outgoing edges incident to vertex in this graph

inDegree

int inDegree(V vertex)

Returns the number of incoming edges incident to vertex. Equivalent to getInEdges(vertex).size().

Parameters:

vertex - the vertex whose indegree is to be calculated

Returns:

the number of incoming edges incident to vertex

outDegree

int outDegree(V vertex)

Returns the number of outgoing edges incident to vertex. Equivalent to getOutEdges(vertex).size().

Parameters:

vertex - the vertex whose outdegree is to be calculated

Returns:

the number of outgoing edges incident to vertex

getSource

V getSource(E directed_edge)

If directed_edge is a directed edge in this graph, returns the source; otherwise returns null. The source of a directed edge d is defined to be the vertex for which d is an outgoing edge. directed_edge is guaranteed to be a directed edge if its EdgeType is DIRECTED.

Parameters:

directed_edge -

Returns:

the source of directed_edge if it is a directed edge in this graph, or null otherwise

getDest

V getDest(E directed_edge)

If directed_edge is a directed edge in this graph, returns the destination; otherwise returns null. The destination of a directed edge d is defined to be the vertex incident to d for which d is an incoming edge. directed_edge is guaranteed to be a directed edge if its EdgeType is DIRECTED.

Parameters:

directed_edge -

Returns:

the destination of directed_edge if it is a directed edge in this graph, or null otherwise

getPredecessors

Collection<V> getPredecessors(V vertex)

Returns a Collection view of the predecessors of vertex in this graph. A predecessor of vertex is defined as a vertex v which is connected to vertex by an edge e, where e is an outgoing edge of v and an incoming edge of vertex.

Parameters:

vertex - the vertex whose predecessors are to be returned

Returns:

a Collection view of the predecessors of vertex in this graph

getSuccessors

Collection<V> getSuccessors(V vertex)

Returns a Collection view of the successors of vertex in this graph. A successor of vertex is defined as a vertex v which is connected to vertex by an edge e, where e is an incoming edge of v and an outgoing edge of vertex.

Parameters:

vertex - the vertex whose predecessors are to be returned

Returns:

a Collection view of the successors of vertex in this graph