com.graphhopper.routing

Class AStar

java.lang.Object

com.graphhopper.routing.AbstractRoutingAlgorithm

com.graphhopper.routing.AStar

All Implemented Interfaces:

RoutingAlgorithm

public class AStar
extends AbstractRoutingAlgorithm

This class implements the A* algorithm according to http://en.wikipedia.org/wiki/A*_search_algorithm

Different distance calculations can be used via setApproximation.

Author:

Peter Karich

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	AStar.AStarEntry

Field Summary

Fields inherited from class com.graphhopper.routing.AbstractRoutingAlgorithm

flagEncoder, graph, inEdgeExplorer, maxVisitedNodes, nodeAccess, outEdgeExplorer, traversalMode, weighting

Constructor Summary

Constructors

Constructor and Description
AStar(Graph graph, FlagEncoder encoder, Weighting weighting, TraversalMode tMode)

Method Summary

Modifier and Type	Method and Description
Path	calcPath(int from, int to) Calculates the best path between the specified nodes.
protected SPTEntry	createSPTEntry(int node, double weight)
protected Path	extractPath() To be overwritten from extending class.
protected boolean	finished() To be overwritten from extending class.
String	getName()
int	getVisitedNodes() Returns the visited nodes after searching.
protected void	initCollections(int size)
AStar	setApproximation(WeightApproximator approx)

Methods inherited from class com.graphhopper.routing.AbstractRoutingAlgorithm

accept, calcPaths, checkAlreadyRun, createEmptyPath, isMaxVisitedNodesExceeded, setEdgeFilter, setMaxVisitedNodes, toString, updateBestPath

Methods inherited from class java.lang.Object

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

Constructor Detail

AStar

public AStar(Graph graph,
             FlagEncoder encoder,
             Weighting weighting,
             TraversalMode tMode)

Method Detail

setApproximation

public AStar setApproximation(WeightApproximator approx)

Parameters:

approx - defines how distance to goal Node is approximated

initCollections

protected void initCollections(int size)

calcPath

public Path calcPath(int from,
                     int to)

Description copied from interface: RoutingAlgorithm

Calculates the best path between the specified nodes.

Returns:

the path. Call the method found() to make sure that the path is valid.

extractPath

protected Path extractPath()

Description copied from class: AbstractRoutingAlgorithm

To be overwritten from extending class. Should we make this available in RoutingAlgorithm interface?

Specified by:

extractPath in class AbstractRoutingAlgorithm

Returns:

true if finished.

createSPTEntry

protected SPTEntry createSPTEntry(int node,
                                  double weight)

Overrides:

createSPTEntry in class AbstractRoutingAlgorithm

finished

protected boolean finished()

Description copied from class: AbstractRoutingAlgorithm

To be overwritten from extending class. Should we make this available in RoutingAlgorithm interface?

Specified by:

finished in class AbstractRoutingAlgorithm

Returns:

true if finished.

getVisitedNodes

public int getVisitedNodes()

Description copied from interface: RoutingAlgorithm

Returns the visited nodes after searching. Useful for debugging.

getName

public String getName()

Specified by:

getName in interface RoutingAlgorithm

Overrides:

getName in class AbstractRoutingAlgorithm

Returns:

name of this algorithm