 All Implemented Interfaces:
it.unimi.dsi.lang.FlyweightPrototype<ImmutableDirectedGraphAdapter>
,Graph<Integer,
it.unimi.dsi.fastutil.ints.IntIntPair>
ImmutableGraph
.
Nodes are instances of Integer
corresponding to the index of a node in WebGraph. Edges
are represented by an IntIntPair
. The left and right element are the source and the
target of the edge. Since the underlying graph is immutable, the resulting graph is unmodifiable.
Edges are immutable and can be tested for equality (e.g., stored in a dictionary).
WebGraph provides methods for successors only, so to adapt a directed graph you must provide both
a graph and its transpose (methods to compute the transpose are available in Transform
).
You need to load an ImmutableGraph
and its transpose using one of the available load
methods, and then build an adapter:
immutableGraph = ImmutableGraph.loadMapped("mygraph"); immutableTranspose = ImmutableGraph.loadMapped("mygrapht"); adapter = new ImmutableDirectedGraphAdapter(immutableGraph, immutableTranspose);
The first graph will be used to implement outgoingEdgesOf(Integer)
, and the second graph
to implement incomingEdgesOf(Integer)
. It is your responsibility that the two provided
graphs are one the transpose of the other (for each arc
x → y in a graph there must be an arc
y → x in the other, and vice versa). No check will be
performed. Note that computing the number of edges of a
graph requires a full scan of the edge set if ImmutableGraph.numArcs()
is not supported
(the first time—then it will be cached).
If you use a load method that does not provide random access, most methods will throw an
UnsupportedOperationException
.
If you know that you will never used methods based on incoming edges
(incomingEdgesOf(Integer)
, inDegreeOf(Integer)
, edgesOf(Integer)
,
degreeOf(Integer)
), you can also use the constructor using just a graph, but all such
methods will throw a NullPointerException
:
immutableGraph = ImmutableGraph.loadMapped("mygraph"); adapter = new ImmutableDirectedGraphAdapter(immutableGraph);
If necessary, you can adapt a big WebGraph
graph with at most Integer.MAX_VALUE
vertices using the suitable
wrapper.
Thread safety
This class is not thread safe: following the FlyweightPrototype
pattern, users can access
concurrently the graph by getting lightweight copies.
Fast adjacency check
As it happens for the sparse representation of JGraphT, usually a WebGraph compressed
representation requires scanning the adjacency list of a node to
test whether a specific arc exists. However, if you adapt
a WebGraph class (such as EFGraph
) which provides skippable iterators with fast skipping, adjacency can be tested more quickly (e.g., essentially
in constant time in the case of EFGraph
).
 Author:
 Sebastiano Vigna
 See Also:

Field Summary
Fields inherited from class org.jgrapht.webgraph.AbstractImmutableGraphAdapter
immutableGraph, m, n
Fields inherited from interface org.jgrapht.Graph
DEFAULT_EDGE_WEIGHT

Constructor Summary
ConstructorDescriptionImmutableDirectedGraphAdapter
(it.unimi.dsi.webgraph.ImmutableGraph immutableGraph) Creates an adapter for a directed immutable graph implementing only methods based on outgoing edges.ImmutableDirectedGraphAdapter
(it.unimi.dsi.webgraph.ImmutableGraph immutableGraph, it.unimi.dsi.webgraph.ImmutableGraph immutableTranspose) Creates an adapter for a directed immutable graph. 
Method Summary
Modifier and TypeMethodDescriptionboolean
containsEdge
(it.unimi.dsi.fastutil.ints.IntIntPair e) Returnstrue
if this graph contains the specified edge.copy()
int
Returns the degree of the specified vertex.Set<it.unimi.dsi.fastutil.ints.IntIntPair>
edgeSet()
Returns a set of the edges contained in this graph.Set<it.unimi.dsi.fastutil.ints.IntIntPair>
Returns a set of all edges touching the specified vertex.getType()
Get the graph type.Set<it.unimi.dsi.fastutil.ints.IntIntPair>
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.GraphIterables<Integer,
it.unimi.dsi.fastutil.ints.IntIntPair> Access the graph using theGraphIterables
interface.protected it.unimi.dsi.fastutil.ints.IntIntPair
makeEdge
(int x, int y) int
outDegreeOf
(Integer vertex) Returns the "out degree" of the specified vertex.Set<it.unimi.dsi.fastutil.ints.IntIntPair>
outgoingEdgesOf
(Integer vertex) Returns a set of all edges outgoing from the specified vertex.Methods inherited from class org.jgrapht.webgraph.AbstractImmutableGraphAdapter
addEdge, addEdge, addVertex, addVertex, containsEdge, containsEdgeFast, containsVertex, getAllEdges, getEdge, getEdgeSource, getEdgeSupplier, getEdgeTarget, getEdgeWeight, getVertexSupplier, removeEdge, removeEdge, removeVertex, setEdgeWeight, vertexSet
Methods inherited from class org.jgrapht.graph.AbstractGraph
assertVertexExist, 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

Constructor Details

ImmutableDirectedGraphAdapter
public ImmutableDirectedGraphAdapter(it.unimi.dsi.webgraph.ImmutableGraph immutableGraph, it.unimi.dsi.webgraph.ImmutableGraph immutableTranspose) Creates an adapter for a directed immutable graph.It is responsibility of the caller that the two provided graphs are one the transpose of the other (for each arc x → y in a graph there must be an arc y → x in the other). If this property is not true, results will be unpredictable.
 Parameters:
immutableGraph
 an immutable graph.immutableTranspose
 its transpose.

ImmutableDirectedGraphAdapter
public ImmutableDirectedGraphAdapter(it.unimi.dsi.webgraph.ImmutableGraph immutableGraph) Creates an adapter for a directed immutable graph implementing only methods based on outgoing edges. Parameters:
immutableGraph
 an immutable graph.


Method Details

makeEdge
protected it.unimi.dsi.fastutil.ints.IntIntPair makeEdge(int x, int y)  Specified by:
makeEdge
in classAbstractImmutableGraphAdapter<it.unimi.dsi.fastutil.ints.IntIntPair>

containsEdge
public boolean containsEdge(it.unimi.dsi.fastutil.ints.IntIntPair 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
. Specified by:
containsEdge
in interfaceGraph<Integer,
it.unimi.dsi.fastutil.ints.IntIntPair>  Parameters:
e
 edge whose presence in this graph is to be tested. Returns:
true
if this graph contains the specified edge.

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. 
degreeOf
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".

edgesOf
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. 
inDegreeOf
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.
 Specified by:
inDegreeOf
in interfaceGraph<Integer,
it.unimi.dsi.fastutil.ints.IntIntPair>  Parameters:
vertex
 vertex whose degree is to be calculated. Returns:
 the degree of the specified vertex.

incomingEdgesOf
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.
 Specified by:
incomingEdgesOf
in interfaceGraph<Integer,
it.unimi.dsi.fastutil.ints.IntIntPair>  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
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.
 Specified by:
outDegreeOf
in interfaceGraph<Integer,
it.unimi.dsi.fastutil.ints.IntIntPair>  Parameters:
vertex
 vertex whose degree is to be calculated. Returns:
 the degree of the specified vertex.

outgoingEdgesOf
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.
 Specified by:
outgoingEdgesOf
in interfaceGraph<Integer,
it.unimi.dsi.fastutil.ints.IntIntPair>  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.

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. 
copy
 Specified by:
copy
in interfaceit.unimi.dsi.lang.FlyweightPrototype<ImmutableDirectedGraphAdapter>

iterables
Description copied from interface:Graph
Access the graph using theGraphIterables
interface. This allows accessing graphs without the restrictions imposed by 32bit arithmetic. Moreover, graph implementations are free to implement this interface without explicitly materializing intermediate results.
