Package edu.uci.ics.jung.algorithms.shortestpath

Class DijkstraShortestPath<V,E>

java.lang.Object

edu.uci.ics.jung.algorithms.shortestpath.DijkstraDistance<V,E>

edu.uci.ics.jung.algorithms.shortestpath.DijkstraShortestPath<V,E>

All Implemented Interfaces:

Distance<V>, ShortestPath<V,E>

public class DijkstraShortestPath<V,E>
extends DijkstraDistance<V,E>
implements ShortestPath<V,E>

Calculates distances and shortest paths using Dijkstra's single-source-shortest-path algorithm. This is a lightweight extension of DijkstraDistance that also stores path information, so that the shortest paths can be reconstructed.

The elements in the maps returned by getIncomingEdgeMap are ordered (that is, returned by the iterator) by nondecreasing distance from source.

Author:

Joshua O'Madadhain, Tom Nelson converted to jung2

See Also:

DijkstraDistance

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected class	DijkstraShortestPath.SourcePathData	For a given source vertex, holds the estimated and final distances, tentative and final assignments of incoming edges on the shortest path from the source vertex, and a priority queue (ordered by estimaed distance) of the vertices for which distances are unknown.

Nested classes/interfaces inherited from class edu.uci.ics.jung.algorithms.shortestpath.DijkstraDistance

DijkstraDistance.SourceData, DijkstraDistance.VertexComparator<V>

Field Summary

Fields inherited from class edu.uci.ics.jung.algorithms.shortestpath.DijkstraDistance

cached, g, max_distance, max_targets, nev, sourceMap

Constructor Summary

Constructors

Constructor	Description
DijkstraShortestPath(Graph<V,E> g)	Creates an instance of DijkstraShortestPath for the specified unweighted graph (that is, all weights 1) which caches results locally.
DijkstraShortestPath(Graph<V,E> g, boolean cached)	Creates an instance of DijkstraShortestPath for the specified unweighted graph (that is, all weights 1) which caches results locally.
DijkstraShortestPath(Graph<V,E> g, com.google.common.base.Function<E,? extends java.lang.Number> nev)	Creates an instance of DijkstraShortestPath for the specified graph and the specified method of extracting weights from edges, which caches results locally.
DijkstraShortestPath(Graph<V,E> g, com.google.common.base.Function<E,? extends java.lang.Number> nev, boolean cached)	Creates an instance of DijkstraShortestPath for the specified graph and the specified method of extracting weights from edges, which caches results locally if and only if cached is true.

Method Summary

Modifier and Type	Method	Description
E	getIncomingEdge(V source, V target)	Returns the last edge on a shortest path from source to target, or null if target is not reachable from source.
java.util.Map<V,E>	getIncomingEdgeMap(V source)	Returns a LinkedHashMap which maps each vertex in the graph (including the source vertex) to the last edge on the shortest path from the source vertex.
java.util.LinkedHashMap<V,E>	getIncomingEdgeMap(V source, int numDests)	Returns a LinkedHashMap which maps each of the closest numDests vertices to the source vertex in the graph (including the source vertex) to the incoming edge along the path from that vertex.
java.util.List<E>	getPath(V source, V target)	Returns a List of the edges on the shortest path from source to target, in order of their occurrence on this path.
protected DijkstraDistance.SourceData	getSourceData(V source)

Methods inherited from class edu.uci.ics.jung.algorithms.shortestpath.DijkstraDistance

enableCaching, getDistance, getDistanceMap, getDistanceMap, getDistanceMap, getEdgesToCheck, reset, reset, setMaxDistance, setMaxTargets, singleSourceShortestPath

Methods inherited from class java.lang.Object

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

Constructor Detail

DijkstraShortestPath

public DijkstraShortestPath(Graph<V,E> g,
                            com.google.common.base.Function<E,? extends java.lang.Number> nev,
                            boolean cached)

Creates an instance of DijkstraShortestPath for the specified graph and the specified method of extracting weights from edges, which caches results locally if and only if cached is true.

Parameters:

g - the graph on which distances will be calculated

nev - the class responsible for returning weights for edges

cached - specifies whether the results are to be cached

DijkstraShortestPath

public DijkstraShortestPath(Graph<V,E> g,
                            com.google.common.base.Function<E,? extends java.lang.Number> nev)

Creates an instance of DijkstraShortestPath for the specified graph and the specified method of extracting weights from edges, which caches results locally.

Parameters:

g - the graph on which distances will be calculated

nev - the class responsible for returning weights for edges

DijkstraShortestPath

public DijkstraShortestPath(Graph<V,E> g)

Creates an instance of DijkstraShortestPath for the specified unweighted graph (that is, all weights 1) which caches results locally.

Parameters:

g - the graph on which distances will be calculated

DijkstraShortestPath

public DijkstraShortestPath(Graph<V,E> g,
                            boolean cached)

Creates an instance of DijkstraShortestPath for the specified unweighted graph (that is, all weights 1) which caches results locally.

Parameters:

g - the graph on which distances will be calculated

cached - specifies whether the results are to be cached

Method Detail

getSourceData

protected DijkstraDistance.SourceData getSourceData(V source)

Overrides:

getSourceData in class DijkstraDistance<V,E>

getIncomingEdge

public E getIncomingEdge(V source,
                         V target)

Returns the last edge on a shortest path from source to target, or null if target is not reachable from source.

If either vertex is not in the graph for which this instance was created, throws IllegalArgumentException.

Parameters:

source - the vertex where the shortest path starts

target - the vertex where the shortest path ends

Returns:

the last edge on a shortest path from source to target or null if target is not reachable from source

getIncomingEdgeMap

public java.util.Map<V,E> getIncomingEdgeMap(V source)

Returns a LinkedHashMap which maps each vertex in the graph (including the source vertex) to the last edge on the shortest path from the source vertex. The map's iterator will return the elements in order of increasing distance from source.

Specified by:

getIncomingEdgeMap in interface ShortestPath<V,E>

Parameters:

source - the vertex from which distances are measured

Returns:

a map from vertices to the last edge on the shortest path to that vertex starting from source

See Also:

DijkstraDistance.getDistanceMap(Object,int), DijkstraDistance.getDistance(Object,Object)

getPath

public java.util.List<E> getPath(V source,
                                 V target)

Returns a List of the edges on the shortest path from source to target, in order of their occurrence on this path. If either vertex is not in the graph for which this instance was created, throws IllegalArgumentException.

Parameters:

source - the starting vertex for the path to generate

target - the ending vertex for the path to generate

Returns:

the edges on the shortest path from source to target, in order of their occurrence

getIncomingEdgeMap

public java.util.LinkedHashMap<V,E> getIncomingEdgeMap(V source,
                                                             int numDests)

Returns a LinkedHashMap which maps each of the closest numDests vertices to the source vertex in the graph (including the source vertex) to the incoming edge along the path from that vertex. Throws an IllegalArgumentException if source is not in this instance's graph, or if numDests is either less than 1 or greater than the number of vertices in the graph.

Parameters:

source - the vertex from which distances are measured

numDests - the number of vertices for which to measure distances

Returns:

a map from each of the closest numDests vertices to the last edge on the shortest path to that vertex starting from source

See Also:

getIncomingEdgeMap(Object), getPath(Object,Object)