org.neo4j.graphalgo
Class GraphAlgoFactory

java.lang.Object
  org.neo4j.graphalgo.GraphAlgoFactory

public abstract class GraphAlgoFactory
extends Object

Static factory methods for the recommended implementations of common graph algorithms for Neo4j. The algorithms exposed here are implementations which are tested extensively and also scale on bigger graphs.

Author:

Mattias Persson

Constructor Summary

GraphAlgoFactory()

Method Summary

static PathFinder<Path>	allPaths(RelationshipExpander expander, int maxDepth) Returns an algorithm which can find all available paths between two nodes.
static PathFinder<Path>	allSimplePaths(RelationshipExpander expander, int maxDepth) Returns an algorithm which can find all simple paths between two nodes.
static PathFinder<WeightedPath>	aStar(RelationshipExpander expander, CostEvaluator<Double> lengthEvaluator, EstimateEvaluator<Double> estimateEvaluator) Returns an PathFinder which uses the A* algorithm to find the cheapest path between two nodes.
static PathFinder<WeightedPath>	dijkstra(RelationshipExpander expander, CostEvaluator<Double> costEvaluator) Returns an PathFinder which uses the Dijkstra algorithm to find the cheapest path between two nodes.
static PathFinder<WeightedPath>	dijkstra(RelationshipExpander expander, String relationshipPropertyRepresentingCost) See dijkstra(RelationshipExpander, CostEvaluator).
static PathFinder<Path>	pathsWithLength(RelationshipExpander expander, int length) Returns an algorithm which can find simple all paths of a certain length between two nodes.
static PathFinder<Path>	shortestPath(RelationshipExpander expander, int maxDepth) Returns an algorithm which can find all shortest paths (that is paths with as short Path.length() as possible) between two nodes.
static PathFinder<Path>	shortestPath(RelationshipExpander expander, int maxDepth, int maxHitCount) Returns an algorithm which can find all shortest paths (that is paths with as short Path.length() as possible) between two nodes.

Methods inherited from class java.lang.Object

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

Constructor Detail

GraphAlgoFactory

public GraphAlgoFactory()

Method Detail

allPaths

public static PathFinder<Path> allPaths(RelationshipExpander expander,
                                        int maxDepth)

Returns an algorithm which can find all available paths between two nodes. These returned paths can contain loops (i.e. a node can occur more than once in any returned path).

Parameters:

expander - the RelationshipExpander to use for expanding Relationships for each Node.

maxDepth - the max Path.length() returned paths are allowed to have.

Returns:

an algorithm which finds all paths between two nodes.

See Also:

AllPaths

allSimplePaths

public static PathFinder<Path> allSimplePaths(RelationshipExpander expander,
                                              int maxDepth)

Returns an algorithm which can find all simple paths between two nodes. These returned paths cannot contain loops (i.e. a node cannot occur more than once in any returned path).

Parameters:

expander - the RelationshipExpander to use for expanding Relationships for each Node.

maxDepth - the max Path.length() returned paths are allowed to have.

Returns:

an algorithm which finds simple paths between two nodes.

See Also:

AllSimplePaths

shortestPath

public static PathFinder<Path> shortestPath(RelationshipExpander expander,
                                            int maxDepth)

Returns an algorithm which can find all shortest paths (that is paths with as short Path.length() as possible) between two nodes. These returned paths cannot contain loops (i.e. a node cannot occur more than once in any returned path).

Parameters:

expander - the RelationshipExpander to use for expanding Relationships for each Node.

maxDepth - the max Path.length() returned paths are allowed to have.

Returns:

an algorithm which finds shortest paths between two nodes.

See Also:

ShortestPath

shortestPath

public static PathFinder<Path> shortestPath(RelationshipExpander expander,
                                            int maxDepth,
                                            int maxHitCount)

Returns an algorithm which can find all shortest paths (that is paths with as short Path.length() as possible) between two nodes. These returned paths cannot contain loops (i.e. a node cannot occur more than once in any returned path).

Parameters:

expander - the RelationshipExpander to use for expanding Relationships for each Node.

maxDepth - the max Path.length() returned paths are allowed to have.

maxResultCount - the maximum number of Paths to return. If this number of found paths are encountered the traversal will stop.

Returns:

an algorithm which finds shortest paths between two nodes.

See Also:

ShortestPath

pathsWithLength

public static PathFinder<Path> pathsWithLength(RelationshipExpander expander,
                                               int length)

Returns an algorithm which can find simple all paths of a certain length between two nodes. These returned paths cannot contain loops (i.e. a node could not occur more than once in any returned path).

Parameters:

expander - the RelationshipExpander to use for expanding Relationships for each Node.

length - the Path.length() returned paths will have, if any paths were found.

Returns:

an algorithm which finds paths of a certain length between two nodes.

See Also:

ShortestPath

aStar

public static PathFinder<WeightedPath> aStar(RelationshipExpander expander,
                                             CostEvaluator<Double> lengthEvaluator,
                                             EstimateEvaluator<Double> estimateEvaluator)

Returns an PathFinder which uses the A* algorithm to find the cheapest path between two nodes. The definition of "cheap" is the lowest possible cost to get from the start node to the end node, where the cost is returned from lengthEvaluator and estimateEvaluator. These returned paths cannot contain loops (i.e. a node cannot occur more than once in any returned path). See http://en.wikipedia.org/wiki/A*_search_algorithm for more information.

Parameters:

expander - the RelationshipExpander to use for expanding Relationships for each Node.

lengthEvaluator - evaluator that can return the cost represented by each relationship the algorithm traverses.

estimateEvaluator - evaluator that returns an (optimistic) estimation of the cost to get from the current node (in the traversal) to the end node.

Returns:

an algorithm which finds the cheapest path between two nodes using the A* algorithm.

See Also:

AStar

dijkstra

public static PathFinder<WeightedPath> dijkstra(RelationshipExpander expander,
                                                CostEvaluator<Double> costEvaluator)

Returns an PathFinder which uses the Dijkstra algorithm to find the cheapest path between two nodes. The definition of "cheap" is the lowest possible cost to get from the start node to the end node, where the cost is returned from costEvaluator. These returned paths cannot contain loops (i.e. a node cannot occur more than once in any returned path). See http://en.wikipedia.org/wiki/Dijkstra%27s_algorithm for more information.

Parameters:

expander - the RelationshipExpander to use for expanding Relationships for each Node.

costEvaluator - evaluator that can return the cost represented by each relationship the algorithm traverses.

Returns:

an algorithm which finds the cheapest path between two nodes using the Dijkstra algorithm.

See Also:

Dijkstra

dijkstra

public static PathFinder<WeightedPath> dijkstra(RelationshipExpander expander,
                                                String relationshipPropertyRepresentingCost)

See dijkstra(RelationshipExpander, CostEvaluator). Uses a cost evaluator which uses the supplied property key to represent the cost (values of type double).

Parameters:

expander - the RelationshipExpander to use for expanding Relationships for each Node.

relationshipPropertyRepresentingCost - the property to represent cost on each relationship the algorithm traverses.

Returns:

an algorithm which finds the cheapest path between two nodes using the Dijkstra algorithm.