org.jgrapht.traverse

Class RandomWalkIterator<V,E>

java.lang.Object

org.jgrapht.traverse.AbstractGraphIterator<V,E>

org.jgrapht.traverse.RandomWalkIterator<V,E>

Type Parameters:

V - vertex type

E - edge type

All Implemented Interfaces:

java.util.Iterator<V>, GraphIterator<V,E>

public class RandomWalkIterator<V,E>
extends AbstractGraphIterator<V,E>

A random-walk iterator for a directed and an undirected graph. At each step selected a randomly (uniformly distributed) edge out of the current vertex edges (in case of directed graph - from the outgoing edges), and follows it to the next vertex. In case a weighted walk is desired (and in case the graph is weighted), edges are selected with probability respective to its weight (out of the total weight of the edges). Walk can be bounded by number of steps (default Long#MAX_VALUE . When the bound is reached the iterator is considered exhausted. Calling next() on exhausted iterator will throw NoSuchElementException. In case a sink (i.e. no edges) vertex is reached, iterator will return null and consecutive calls to next() will throw NoSuchElementException. For this iterator to work correctly the graph must not be modified during iteration. Currently there are no means to ensure that, nor to fail-fast. The results of such modifications are undefined.

Constructor Summary

Constructors

Constructor and Description
RandomWalkIterator(Graph<V,E> graph) Creates a new iterator for the specified graph.
RandomWalkIterator(Graph<V,E> graph, V startVertex) Creates a new iterator for the specified graph.
RandomWalkIterator(Graph<V,E> graph, V startVertex, boolean isWeighted) Creates a new iterator for the specified graph.
RandomWalkIterator(Graph<V,E> graph, V startVertex, boolean isWeighted, long maxSteps) Creates a new iterator for the specified graph.

Method Summary

Modifier and Type	Method and Description
boolean	hasNext()
V	next()

Methods inherited from class org.jgrapht.traverse.AbstractGraphIterator

addTraversalListener, isCrossComponentTraversal, isReuseEvents, remove, removeTraversalListener, setCrossComponentTraversal, setReuseEvents

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.util.Iterator

forEachRemaining

Constructor Detail

RandomWalkIterator

public RandomWalkIterator(Graph<V,E> graph)

Creates a new iterator for the specified graph. Iteration will start at arbitrary vertex. Walk is un-weighted and bounded by Long#MAX_VALUE steps.

Parameters:

graph - the graph to be iterated.

Throws:

java.lang.IllegalArgumentException - if graph==null or does not contain startVertex

RandomWalkIterator

public RandomWalkIterator(Graph<V,E> graph,
                          V startVertex)

Creates a new iterator for the specified graph. Iteration will start at the specified start vertex. If the specified start vertex is null, Iteration will start at an arbitrary graph vertex. Walk is un-weighted and bounded by Long#MAX_VALUE steps.

Parameters:

graph - the graph to be iterated.

startVertex - the vertex iteration to be started.

Throws:

java.lang.IllegalArgumentException - if graph==null or does not contain startVertex

RandomWalkIterator

public RandomWalkIterator(Graph<V,E> graph,
                          V startVertex,
                          boolean isWeighted)

Creates a new iterator for the specified graph. Iteration will start at the specified start vertex. If the specified start vertex is null, Iteration will start at an arbitrary graph vertex. Walk is bounded by Long#MAX_VALUE steps.

Parameters:

graph - the graph to be iterated.

startVertex - the vertex iteration to be started.

isWeighted - set to true if a weighted walk is desired.

Throws:

java.lang.IllegalArgumentException - if graph==null or does not contain startVertex

RandomWalkIterator

public RandomWalkIterator(Graph<V,E> graph,
                          V startVertex,
                          boolean isWeighted,
                          long maxSteps)

Creates a new iterator for the specified graph. Iteration will start at the specified start vertex. If the specified start vertex is null, Iteration will start at an arbitrary graph vertex. Walk is bounded by the provided number steps.

Parameters:

graph - the graph to be iterated.

startVertex - the vertex iteration to be started.

isWeighted - set to true if a weighted walk is desired.

maxSteps - number of steps before walk is exhausted.

Throws:

java.lang.IllegalArgumentException - if graph==null or does not contain startVertex

Method Detail

hasNext

public boolean hasNext()

See Also:

Iterator.hasNext()

next

public V next()

See Also:

Iterator.next()