Class SparseIntUndirectedGraph
 java.lang.Object

 org.jgrapht.graph.AbstractGraph<Integer,Integer>

 org.jgrapht.opt.graph.sparse.SparseIntUndirectedGraph

 Direct Known Subclasses:
SparseIntUndirectedWeightedGraph
public class SparseIntUndirectedGraph extends AbstractGraph<Integer,Integer>
Sparse undirected graph.Assuming the graph has $n$ vertices, the vertices are numbered from $0$ to $n1$. Similarly, edges are numbered from $0$ to $m1$ where $m$ is the total number of edges.
It stores the boolean incidence matrix of the graph (rows are vertices and columns are edges) as Compressed Sparse Rows (CSR). In order to also support constant time source and target lookups from an edge identifier we also store the transposed of the incidence matrix again in compressed sparse rows format. This is a classic format for writeonce readmany use cases. Thus, the graph is unmodifiable.
The question of whether a sparse or dense representation is more appropriate is highly dependent on various factors such as the graph, the machine running the algorithm and the algorithm itself. Wilkinson defined a matrix as "sparse" if it has enough zeros that it pays to take advantage of them. For more details see
 Wilkinson, J. H. 1971. Linear algebra; part II: the algebraic eigenvalue problem. In Handbook for Automatic Computation, J. H. Wilkinson and C. Reinsch, Eds. Vol. 2. SpringerVerlag, Berlin, New York.
 Author:
 Dimitrios Michail


Field Summary
Fields Modifier and Type Field Description protected org.jgrapht.opt.graph.sparse.CSRBooleanMatrix
incidenceMatrix
protected org.jgrapht.opt.graph.sparse.CSRBooleanMatrix
incidenceMatrixT
protected static String
UNMODIFIABLE

Fields inherited from interface org.jgrapht.Graph
DEFAULT_EDGE_WEIGHT


Constructor Summary
Constructors Constructor Description SparseIntUndirectedGraph(int numVertices, List<Pair<Integer,Integer>> edges)
Create a new graph from an edge list

Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description Integer
addEdge(Integer sourceVertex, Integer targetVertex)
Creates a new edge in this graph, going from the source vertex to the target vertex, and returns the created edge.boolean
addEdge(Integer sourceVertex, Integer targetVertex, Integer e)
Adds the specified edge to this graph, going from the source vertex to the target vertex.Integer
addVertex()
Creates a new vertex in this graph and returns it.boolean
addVertex(Integer v)
Adds the specified vertex to this graph if not already present.protected boolean
assertEdgeExist(Integer e)
Ensures that the specified edge exists in this graph, or else throws exception.protected boolean
assertVertexExist(Integer v)
Ensures that the specified vertex exists in this graph, or else throws exception.boolean
containsEdge(Integer e)
Returnstrue
if this graph contains the specified edge.boolean
containsVertex(Integer v)
Returnstrue
if this graph contains the specified vertex.int
degreeOf(Integer vertex)
Returns the degree of the specified vertex.Set<Integer>
edgeSet()
Returns a set of the edges contained in this graph.Set<Integer>
edgesOf(Integer vertex)
Returns a set of all edges touching the specified vertex.Set<Integer>
getAllEdges(Integer sourceVertex, Integer targetVertex)
Returns a set of all edges connecting source vertex to target vertex if such vertices exist in this graph.Integer
getEdge(Integer sourceVertex, Integer targetVertex)
Returns an edge connecting source vertex to target vertex if such vertices and such edge exist in this graph.Integer
getEdgeSource(Integer e)
Returns the source vertex of an edge.Supplier<Integer>
getEdgeSupplier()
Return the edge supplier that the graph uses whenever it needs to create new edges.Integer
getEdgeTarget(Integer e)
Returns the target vertex of an edge.double
getEdgeWeight(Integer e)
Returns the weight assigned to a given edge.GraphType
getType()
Get the graph type.Supplier<Integer>
getVertexSupplier()
Return the vertex supplier that the graph uses whenever it needs to create new vertices.Set<Integer>
incomingEdgesOf(Integer vertex)
Returns a set of all edges incoming into the specified vertex.int
inDegreeOf(Integer vertex)
Returns the "in degree" of the specified vertex.int
outDegreeOf(Integer vertex)
Returns the "out degree" of the specified vertex.Set<Integer>
outgoingEdgesOf(Integer vertex)
Returns a set of all edges outgoing from the specified vertex.boolean
removeEdge(Integer e)
Removes the specified edge from the graph.Integer
removeEdge(Integer sourceVertex, Integer targetVertex)
Removes an edge going from source vertex to target vertex, if such vertices and such edge exist in this graph.boolean
removeVertex(Integer v)
Removes the specified vertex from this graph including all its touching edges if present.void
setEdgeWeight(Integer e, double weight)
Assigns a weight to an edge.Set<Integer>
vertexSet()
Returns a set of the vertices contained in this graph.
Methods inherited from class org.jgrapht.graph.AbstractGraph
containsEdge, equals, hashCode, removeAllEdges, removeAllEdges, removeAllEdges, removeAllVertices, toString, toStringFromSets

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.jgrapht.Graph
setEdgeWeight




Field Detail

UNMODIFIABLE
protected static final String UNMODIFIABLE
 See Also:
 Constant Field Values

incidenceMatrix
protected org.jgrapht.opt.graph.sparse.CSRBooleanMatrix incidenceMatrix

incidenceMatrixT
protected org.jgrapht.opt.graph.sparse.CSRBooleanMatrix incidenceMatrixT


Method Detail

getVertexSupplier
public Supplier<Integer> getVertexSupplier()
Description copied from interface:Graph
Return the vertex supplier that the graph uses whenever it needs to create new vertices.A graph uses the vertex supplier to create new vertex objects whenever a user calls method
Graph.addVertex()
. Users can also create the vertex in user code and then use methodGraph.addVertex(Object)
to add the vertex.In contrast with the
Supplier
interface, the vertex supplier has the additional requirement that a new and distinct result is returned every time it is invoked. More specifically for a new vertex to be added in a graphv
must not be equal to any other vertex in the graph. More formally, the graph must not contain any vertexv2
such thatv2.equals(v)
.Care must also be taken when interchanging calls to methods
Graph.addVertex(Object)
andGraph.addVertex()
. In such a case the user must make sure never to add vertices in the graph using methodGraph.addVertex(Object)
, which are going to be returned in the future by the supplied vertex supplier. Such a sequence will result into anIllegalArgumentException
when calling methodGraph.addVertex()
. Returns:
 the vertex supplier or
null
if the graph has no such supplier

getEdgeSupplier
public Supplier<Integer> getEdgeSupplier()
Description copied from interface:Graph
Return the edge supplier that the graph uses whenever it needs to create new edges.A graph uses the edge supplier to create new edge objects whenever a user calls method
Graph.addEdge(Object, Object)
. Users can also create the edge in user code and then use methodGraph.addEdge(Object, Object, Object)
to add the edge.In contrast with the
Supplier
interface, the edge supplier has the additional requirement that a new and distinct result is returned every time it is invoked. More specifically for a new edge to be added in a graphe
must not be equal to any other edge in the graph (even if the graph allows edgemultiplicity). More formally, the graph must not contain any edgee2
such thate2.equals(e)
. Returns:
 the edge supplier
null
if the graph has no such supplier

addEdge
public Integer addEdge(Integer sourceVertex, Integer 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 edgemultiplicity. 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's edge supplier (seeGraph.getEdgeSupplier()
). For the new edge to be addede
must not be equal to any other edge the graph (even if the graph allows edgemultiplicity). 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 and returnsnull
.If the underlying graph implementation's
Graph.getEdgeSupplier()
returnsnull
, then this method cannot create edges and throws anUnsupportedOperationException
. 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.getEdgeSupplier()

addEdge
public boolean addEdge(Integer sourceVertex, Integer targetVertex, Integer 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 returnsfalse
. Some graphs do not allow edgemultiplicity. 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.
 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)
,Graph.getEdgeSupplier()

addVertex
public Integer addVertex()
Description copied from interface:Graph
Creates a new vertex in this graph and returns it.This method creates the new vertex
v
using this graph's vertex supplier (seeGraph.getVertexSupplier()
). For the new vertex to be addedv
must not be equal to any other vertex in the graph. More formally, the graph must not contain any vertexv2
such thatv2.equals(v)
. If suchv2
is found then the newly created vertexv
is abandoned, the method leaves this graph unchanged and throws anIllegalArgumentException
.If the underlying graph implementation's
Graph.getVertexSupplier()
returnsnull
, then this method cannot create vertices and throws anUnsupportedOperationException
.Care must also be taken when interchanging calls to methods
Graph.addVertex(Object)
andGraph.addVertex()
. In such a case the user must make sure never to add vertices in the graph using methodGraph.addVertex(Object)
, which are going to be returned in the future by the supplied vertex supplier. Such a sequence will result into anIllegalArgumentException
when calling methodGraph.addVertex()
. Returns:
 The newly created vertex if added to the graph.
 See Also:
Graph.getVertexSupplier()

addVertex
public boolean addVertex(Integer v)
Description copied from interface:Graph
Adds the specified vertex to this graph if not already present. More formally, adds the specified vertex,v
, to this graph if this graph contains no vertexu
such thatu.equals(v)
. If this graph already contains such vertex, the call leaves this graph unchanged and returnsfalse
. In combination with the restriction on constructors, this ensures that graphs never contain duplicate vertices. Parameters:
v
 vertex to be added to this graph. Returns:
true
if this graph did not already contain the specified vertex.

containsEdge
public boolean containsEdge(Integer e)
Description copied from interface:Graph
Returnstrue
if this graph contains the specified edge. More formally, returnstrue
if and only if this graph contains an edgee2
such thate.equals(e2)
. If the specified edge isnull
returnsfalse
. Parameters:
e
 edge whose presence in this graph is to be tested. Returns:
true
if this graph contains the specified edge.

containsVertex
public boolean containsVertex(Integer v)
Description copied from interface:Graph
Returnstrue
if this graph contains the specified vertex. More formally, returnstrue
if and only if this graph contains a vertexu
such thatu.equals(v)
. If the specified vertex isnull
returnsfalse
. Parameters:
v
 vertex whose presence in this graph is to be tested. Returns:
true
if this graph contains the specified vertex.

edgeSet
public Set<Integer> 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. Returns:
 a set of the edges contained in this graph.

degreeOf
public int degreeOf(Integer vertex)
Description copied from interface:Graph
Returns the degree of the specified vertex.A degree of a vertex in an undirected graph is the number of edges touching that vertex. Edges with same source and target vertices (selfloops) are counted twice.
In directed graphs this method returns the sum of the "in degree" and the "out degree".
 Parameters:
vertex
 vertex whose degree is to be calculated. Returns:
 the degree of the specified vertex.

edgesOf
public Set<Integer> edgesOf(Integer 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. 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.

inDegreeOf
public int inDegreeOf(Integer vertex)
Description copied from interface:Graph
Returns the "in degree" of the specified vertex.The "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.
In the case of undirected graphs this method returns the number of edges touching the vertex. Edges with same source and target vertices (selfloops) are counted twice.
 Parameters:
vertex
 vertex whose degree is to be calculated. Returns:
 the degree of the specified vertex.

incomingEdgesOf
public Set<Integer> incomingEdgesOf(Integer vertex)
Description copied from interface:Graph
Returns a set of all edges incoming into the specified vertex.In the case of undirected graphs this method returns all edges touching the vertex, thus, some of the returned edges may have their source and target vertices in the opposite order.
 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.

outDegreeOf
public int outDegreeOf(Integer vertex)
Description copied from interface:Graph
Returns the "out degree" of the specified vertex.The "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.
In the case of undirected graphs this method returns the number of edges touching the vertex. Edges with same source and target vertices (selfloops) are counted twice.
 Parameters:
vertex
 vertex whose degree is to be calculated. Returns:
 the degree of the specified vertex.

outgoingEdgesOf
public Set<Integer> outgoingEdgesOf(Integer vertex)
Description copied from interface:Graph
Returns a set of all edges outgoing from the specified vertex.In the case of undirected graphs this method returns all edges touching the vertex, thus, some of the returned edges may have their source and target vertices in the opposite order.
 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.

removeEdge
public Integer removeEdge(Integer sourceVertex, Integer 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. Parameters:
sourceVertex
 source vertex of the edge.targetVertex
 target vertex of the edge. Returns:
 The removed edge, or
null
if no edge removed.

removeEdge
public boolean removeEdge(Integer 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. Returnstrue
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
. Parameters:
e
 edge to be removed from this graph, if present. Returns:
true
if and only if the graph contained the specified edge.

removeVertex
public boolean removeVertex(Integer 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. Returnstrue
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
. Parameters:
v
 vertex to be removed from this graph, if present. Returns:
true
if the graph contained the specified vertex;false
otherwise.

vertexSet
public Set<Integer> 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. Returns:
 a set view of the vertices contained in this graph.

getType
public GraphType getType()
Description copied from interface:Graph
Get the graph type. The graph type can be used to query for additional metadata such as whether the graph supports directed or undirected edges, selfloops, multiple (parallel) edges, weights, etc. Returns:
 the graph type

getEdgeWeight
public double getEdgeWeight(Integer e)
Description copied from interface:Graph
Returns the weight assigned to a given edge. Unweighted graphs return 1.0 (as defined byGraph.DEFAULT_EDGE_WEIGHT
), allowing weightedgraph algorithms to apply to them when meaningful. Parameters:
e
 edge of interest Returns:
 edge weight

setEdgeWeight
public void setEdgeWeight(Integer e, double weight)
Description copied from interface:Graph
Assigns a weight to an edge. Parameters:
e
 edge on which to set weightweight
 new weight for edge

getEdgeSource
public Integer getEdgeSource(Integer 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). Parameters:
e
 edge of interest Returns:
 source vertex

getEdgeTarget
public Integer getEdgeTarget(Integer 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). Parameters:
e
 edge of interest Returns:
 target vertex

getEdge
public Integer getEdge(Integer sourceVertex, Integer targetVertex)
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.
This operation costs $O(d)$ where $d$ is the degree of the source vertex. Parameters:
sourceVertex
 source vertex of the edge.targetVertex
 target vertex of the edge. Returns:
 an edge connecting source vertex to target vertex.

getAllEdges
public Set<Integer> getAllEdges(Integer sourceVertex, Integer targetVertex)
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.
This operation costs $O(d)$ where $d$ is the degree of the source vertex. 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.

assertVertexExist
protected boolean assertVertexExist(Integer v)
Ensures that the specified vertex exists in this graph, or else throws exception. Overrides:
assertVertexExist
in classAbstractGraph<Integer,Integer>
 Parameters:
v
 vertex Returns:
true
if this assertion holds. Throws:
IllegalArgumentException
 if specified vertex does not exist in this graph.

assertEdgeExist
protected boolean assertEdgeExist(Integer e)
Ensures that the specified edge exists in this graph, or else throws exception. Parameters:
e
 edge Returns:
true
if this assertion holds. Throws:
IllegalArgumentException
 if specified edge does not exist in this graph.

