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Removed option to find path with exact depth from ShortestPath
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It does not make sense to find a shortest path with specified length and ExactDepthPathFinder already provides that functionality.
 - Added further testing for ExactDepthPathFinder.
 - GraphAlgoFactory now uses ExactDepthPathFinder instead of ShortsetPath.
 - Fixed ExactDepthPathFinder not handeling neighbouring node (depth 1).

Fixing imports
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@burqen
burqen committed May 19, 2015
1 parent 3132c99 commit 6884c91
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Showing 8 changed files with 350 additions and 224 deletions.
95 changes: 48 additions & 47 deletions community/graph-algo/src/main/java/org/neo4j/graphalgo/GraphAlgoFactory.java
View file
Expand Up @@ -23,6 +23,7 @@
import org.neo4j.graphalgo.impl.path.AllPaths; import org.neo4j.graphalgo.impl.path.AllPaths;
import org.neo4j.graphalgo.impl.path.AllSimplePaths; import org.neo4j.graphalgo.impl.path.AllSimplePaths;
import org.neo4j.graphalgo.impl.path.Dijkstra; import org.neo4j.graphalgo.impl.path.Dijkstra;
import org.neo4j.graphalgo.impl.path.ExactDepthPathFinder;
import org.neo4j.graphalgo.impl.path.ShortestPath; import org.neo4j.graphalgo.impl.path.ShortestPath;
import org.neo4j.graphalgo.impl.util.DoubleEvaluator; import org.neo4j.graphalgo.impl.util.DoubleEvaluator;
import org.neo4j.graphdb.Node; import org.neo4j.graphdb.Node;
Expand All @@ -37,7 +38,7 @@
* Static factory methods for the recommended implementations of common * Static factory methods for the recommended implementations of common
* graph algorithms for Neo4j. The algorithms exposed here are implementations * graph algorithms for Neo4j. The algorithms exposed here are implementations
* which are tested extensively and also scale on bigger graphs. * which are tested extensively and also scale on bigger graphs.
* *
* @author Mattias Persson * @author Mattias Persson
*/ */
public abstract class GraphAlgoFactory public abstract class GraphAlgoFactory
Expand Down Expand Up @@ -73,7 +74,7 @@ public static PathFinder<Path> allPaths( PathExpander expander, int maxDepth )
{ {
return new AllPaths( maxDepth, expander ); return new AllPaths( maxDepth, expander );
} }

/** /**
* Returns an algorithm which can find all simple paths between two * Returns an algorithm which can find all simple paths between two
* nodes. These returned paths cannot contain loops (i.e. a node cannot * nodes. These returned paths cannot contain loops (i.e. a node cannot
Expand Down Expand Up @@ -107,7 +108,7 @@ public static PathFinder<Path> allSimplePaths( PathExpander expander,
{ {
return new AllSimplePaths( maxDepth, expander ); return new AllSimplePaths( maxDepth, expander );
} }

/** /**
* Returns an algorithm which can find all shortest paths (that is paths * Returns an algorithm which can find all shortest paths (that is paths
* with as short {@link Path#length()} as possible) between two nodes. These * with as short {@link Path#length()} as possible) between two nodes. These
Expand All @@ -130,7 +131,7 @@ public static PathFinder<Path> shortestPath( RelationshipExpander expander, int
* with as short {@link Path#length()} as possible) between two nodes. These * with as short {@link Path#length()} as possible) between two nodes. These
* returned paths cannot contain loops (i.e. a node cannot occur more than * returned paths cannot contain loops (i.e. a node cannot occur more than
* once in any returned path). * once in any returned path).
* *
* @param expander the {@link PathExpander} to use for expanding * @param expander the {@link PathExpander} to use for expanding
* {@link Relationship}s for each {@link Path}. * {@link Relationship}s for each {@link Path}.
* @param maxDepth the max {@link Path#length()} returned paths are allowed * @param maxDepth the max {@link Path#length()} returned paths are allowed
Expand All @@ -141,13 +142,13 @@ public static PathFinder<Path> shortestPath( PathExpander expander, int maxDepth
{ {
return new ShortestPath( maxDepth, expander ); return new ShortestPath( maxDepth, expander );
} }

/** /**
* Returns an algorithm which can find all shortest paths (that is paths * Returns an algorithm which can find all shortest paths (that is paths
* with as short {@link Path#length()} as possible) between two nodes. These * with as short {@link Path#length()} as possible) between two nodes. These
* returned paths cannot contain loops (i.e. a node cannot occur more than * returned paths cannot contain loops (i.e. a node cannot occur more than
* once in any returned path). * once in any returned path).
* *
* @param expander the {@link RelationshipExpander} to use for expanding * @param expander the {@link RelationshipExpander} to use for expanding
* {@link Relationship}s for each {@link Node}. * {@link Relationship}s for each {@link Node}.
* @param maxDepth the max {@link Path#length()} returned paths are allowed * @param maxDepth the max {@link Path#length()} returned paths are allowed
Expand All @@ -160,13 +161,13 @@ public static PathFinder<Path> shortestPath( RelationshipExpander expander, int
{ {
return new ShortestPath( maxDepth, expander, maxHitCount ); return new ShortestPath( maxDepth, expander, maxHitCount );
} }

/** /**
* Returns an algorithm which can find all shortest paths (that is paths * Returns an algorithm which can find all shortest paths (that is paths
* with as short {@link Path#length()} as possible) between two nodes. These * with as short {@link Path#length()} as possible) between two nodes. These
* returned paths cannot contain loops (i.e. a node cannot occur more than * returned paths cannot contain loops (i.e. a node cannot occur more than
* once in any returned path). * once in any returned path).
* *
* @param expander the {@link PathExpander} to use for expanding * @param expander the {@link PathExpander} to use for expanding
* {@link Relationship}s for each {@link Path}. * {@link Relationship}s for each {@link Path}.
* @param maxDepth the max {@link Path#length()} returned paths are allowed * @param maxDepth the max {@link Path#length()} returned paths are allowed
Expand All @@ -179,12 +180,12 @@ public static PathFinder<Path> shortestPath( PathExpander expander, int maxDepth
{ {
return new ShortestPath( maxDepth, expander, maxHitCount ); return new ShortestPath( maxDepth, expander, maxHitCount );
} }

/** /**
* Returns an algorithm which can find simple all paths of a certain 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 * between two nodes. These returned paths cannot contain loops (i.e. a node
* could not occur more than once in any returned path). * could not occur more than once in any returned path).
* *
* @param expander the {@link RelationshipExpander} to use for expanding * @param expander the {@link RelationshipExpander} to use for expanding
* {@link Relationship}s for each {@link Node}. * {@link Relationship}s for each {@link Node}.
* @param length the {@link Path#length()} returned paths will have, if any * @param length the {@link Path#length()} returned paths will have, if any
Expand All @@ -193,14 +194,14 @@ public static PathFinder<Path> shortestPath( PathExpander expander, int maxDepth
*/ */
public static PathFinder<Path> pathsWithLength( RelationshipExpander expander, int length ) public static PathFinder<Path> pathsWithLength( RelationshipExpander expander, int length )
{ {
return new ShortestPath( length, expander, Integer.MAX_VALUE, true ); return new ExactDepthPathFinder( expander, length, Integer.MAX_VALUE, false );
} }

/** /**
* Returns an algorithm which can find simple all paths of a certain 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 * between two nodes. These returned paths cannot contain loops (i.e. a node
* could not occur more than once in any returned path). * could not occur more than once in any returned path).
* *
* @param expander the {@link PathExpander} to use for expanding * @param expander the {@link PathExpander} to use for expanding
* {@link Relationship}s for each {@link Node}. * {@link Relationship}s for each {@link Node}.
* @param length the {@link Path#length()} returned paths will have, if any * @param length the {@link Path#length()} returned paths will have, if any
Expand All @@ -209,20 +210,20 @@ public static PathFinder<Path> pathsWithLength( RelationshipExpander expander, i
*/ */
public static PathFinder<Path> pathsWithLength( PathExpander expander, int length ) public static PathFinder<Path> pathsWithLength( PathExpander expander, int length )
{ {
return new ShortestPath( length, expander, Integer.MAX_VALUE, true ); return new ExactDepthPathFinder( expander, length, Integer.MAX_VALUE, false );
} }

/** /**
* Returns a {@link PathFinder} which uses the A* algorithm to find the * Returns a {@link PathFinder} which uses the A* algorithm to find the
* cheapest path between two nodes. The definition of "cheap" is the lowest * 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 * possible cost to get from the start node to the end node, where the cost
* is returned from {@code lengthEvaluator} and {@code estimateEvaluator}. * is returned from {@code lengthEvaluator} and {@code estimateEvaluator}.
* These returned paths cannot contain loops (i.e. a node cannot occur more * These returned paths cannot contain loops (i.e. a node cannot occur more
* than once in any returned path). * than once in any returned path).
* *
* See http://en.wikipedia.org/wiki/A*_search_algorithm for more * See http://en.wikipedia.org/wiki/A*_search_algorithm for more
* information. * information.
* *
* @param expander the {@link RelationshipExpander} to use for expanding * @param expander the {@link RelationshipExpander} to use for expanding
* {@link Relationship}s for each {@link Node}. * {@link Relationship}s for each {@link Node}.
* @param lengthEvaluator evaluator that can return the cost represented * @param lengthEvaluator evaluator that can return the cost represented
Expand All @@ -246,10 +247,10 @@ public static PathFinder<WeightedPath> aStar( RelationshipExpander expander,
* is returned from {@code lengthEvaluator} and {@code estimateEvaluator}. * is returned from {@code lengthEvaluator} and {@code estimateEvaluator}.
* These returned paths cannot contain loops (i.e. a node cannot occur more * These returned paths cannot contain loops (i.e. a node cannot occur more
* than once in any returned path). * than once in any returned path).
* *
* See http://en.wikipedia.org/wiki/A*_search_algorithm for more * See http://en.wikipedia.org/wiki/A*_search_algorithm for more
* information. * information.
* *
* @param expander the {@link PathExpander} to use for expanding * @param expander the {@link PathExpander} to use for expanding
* {@link Relationship}s for each {@link Path}. * {@link Relationship}s for each {@link Path}.
* @param lengthEvaluator evaluator that can return the cost represented * @param lengthEvaluator evaluator that can return the cost represented
Expand All @@ -265,18 +266,18 @@ public static PathFinder<WeightedPath> aStar( PathExpander expander,
{ {
return new AStar( expander, lengthEvaluator, estimateEvaluator ); return new AStar( expander, lengthEvaluator, estimateEvaluator );
} }

/** /**
* Returns a {@link PathFinder} which uses the Dijkstra algorithm to find * Returns a {@link PathFinder} which uses the Dijkstra algorithm to find
* the cheapest path between two nodes. The definition of "cheap" is the * 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 * lowest possible cost to get from the start node to the end node, where
* the cost is returned from {@code costEvaluator}. These returned paths * the cost is returned from {@code costEvaluator}. These returned paths
* cannot contain loops (i.e. a node cannot occur more than once in any * cannot contain loops (i.e. a node cannot occur more than once in any
* returned path). * returned path).
* *
* See http://en.wikipedia.org/wiki/Dijkstra%27s_algorithm for more * See http://en.wikipedia.org/wiki/Dijkstra%27s_algorithm for more
* information. * information.
* *
* @param expander the {@link RelationshipExpander} to use for expanding * @param expander the {@link RelationshipExpander} to use for expanding
* {@link Relationship}s for each {@link Node}. * {@link Relationship}s for each {@link Node}.
* @param costEvaluator evaluator that can return the cost represented * @param costEvaluator evaluator that can return the cost represented
Expand All @@ -289,18 +290,18 @@ public static PathFinder<WeightedPath> dijkstra( RelationshipExpander expander,
{ {
return new Dijkstra( expander, costEvaluator ); return new Dijkstra( expander, costEvaluator );
} }

/** /**
* Returns a {@link PathFinder} which uses the Dijkstra algorithm to find * Returns a {@link PathFinder} which uses the Dijkstra algorithm to find
* the cheapest path between two nodes. The definition of "cheap" is the * 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 * lowest possible cost to get from the start node to the end node, where
* the cost is returned from {@code costEvaluator}. These returned paths * the cost is returned from {@code costEvaluator}. These returned paths
* cannot contain loops (i.e. a node cannot occur more than once in any * cannot contain loops (i.e. a node cannot occur more than once in any
* returned path). * returned path).
* *
* See http://en.wikipedia.org/wiki/Dijkstra%27s_algorithm for more * See http://en.wikipedia.org/wiki/Dijkstra%27s_algorithm for more
* information. * information.
* *
* @param expander the {@link PathExpander} to use for expanding * @param expander the {@link PathExpander} to use for expanding
* {@link Relationship}s for each {@link Path}. * {@link Relationship}s for each {@link Path}.
* @param costEvaluator evaluator that can return the cost represented * @param costEvaluator evaluator that can return the cost represented
Expand All @@ -313,13 +314,13 @@ public static PathFinder<WeightedPath> dijkstra( PathExpander expander,
{ {
return new Dijkstra( expander, costEvaluator ); return new Dijkstra( expander, costEvaluator );
} }

/** /**
* See {@link #dijkstra(RelationshipExpander, CostEvaluator)}. * See {@link #dijkstra(RelationshipExpander, CostEvaluator)}.
* *
* Uses a cost evaluator which uses the supplied property key to * Uses a cost evaluator which uses the supplied property key to
* represent the cost (values of type <bold>double</bold>). * represent the cost (values of type <bold>double</bold>).
* *
* @param expander the {@link RelationshipExpander} to use for expanding * @param expander the {@link RelationshipExpander} to use for expanding
* {@link Relationship}s for each {@link Node}. * {@link Relationship}s for each {@link Node}.
* @param relationshipPropertyRepresentingCost the property to represent cost * @param relationshipPropertyRepresentingCost the property to represent cost
Expand All @@ -332,13 +333,13 @@ public static PathFinder<WeightedPath> dijkstra( RelationshipExpander expander,
{ {
return dijkstra( expander, new DoubleEvaluator( relationshipPropertyRepresentingCost ) ); return dijkstra( expander, new DoubleEvaluator( relationshipPropertyRepresentingCost ) );
} }

/** /**
* See {@link #dijkstra(RelationshipExpander, CostEvaluator)}. * See {@link #dijkstra(RelationshipExpander, CostEvaluator)}.
* *
* Uses a cost evaluator which uses the supplied property key to * Uses a cost evaluator which uses the supplied property key to
* represent the cost (values of type <bold>double</bold>). * represent the cost (values of type <bold>double</bold>).
* *
* @param expander the {@link PathExpander} to use for expanding * @param expander the {@link PathExpander} to use for expanding
* {@link Relationship}s for each {@link Path}. * {@link Relationship}s for each {@link Path}.
* @param relationshipPropertyRepresentingCost the property to represent cost * @param relationshipPropertyRepresentingCost the property to represent cost
Expand All @@ -351,13 +352,13 @@ public static PathFinder<WeightedPath> dijkstra( PathExpander expander,
{ {
return dijkstra( expander, new DoubleEvaluator( relationshipPropertyRepresentingCost ) ); return dijkstra( expander, new DoubleEvaluator( relationshipPropertyRepresentingCost ) );
} }

/** /**
* See {@link #dijkstra(RelationshipExpander, CostEvaluator)}. * See {@link #dijkstra(RelationshipExpander, CostEvaluator)}.
* *
* Uses a cost evaluator which uses the supplied property key to * Uses a cost evaluator which uses the supplied property key to
* represent the cost (values of type <bold>double</bold>). * represent the cost (values of type <bold>double</bold>).
* *
* @param expander the {@link PathExpander} to use for expanding * @param expander the {@link PathExpander} to use for expanding
* {@link Relationship}s for each {@link Path}. * {@link Relationship}s for each {@link Path}.
* @param stateFactory initial state for the traversal branches. * @param stateFactory initial state for the traversal branches.
Expand All @@ -373,10 +374,10 @@ public static PathFinder<WeightedPath> dijkstra( PathExpander expander,


/** /**
* See {@link #dijkstra(RelationshipExpander, CostEvaluator)}. * See {@link #dijkstra(RelationshipExpander, CostEvaluator)}.
* *
* Uses a cost evaluator which uses the supplied property key to * Uses a cost evaluator which uses the supplied property key to
* represent the cost (values of type <bold>double</bold>). * represent the cost (values of type <bold>double</bold>).
* *
* @param expander the {@link PathExpander} to use for expanding * @param expander the {@link PathExpander} to use for expanding
* {@link Relationship}s for each {@link Path}. * {@link Relationship}s for each {@link Path}.
* @param stateFactory initial state for the traversal branches. * @param stateFactory initial state for the traversal branches.
Expand All @@ -389,13 +390,13 @@ public static PathFinder<WeightedPath> dijkstra( PathExpander expander,
{ {
return new Dijkstra( expander, stateFactory, costEvaluator ); return new Dijkstra( expander, stateFactory, costEvaluator );
} }

/** /**
* See {@link #dijkstra(RelationshipExpander, CostEvaluator)}. * See {@link #dijkstra(RelationshipExpander, CostEvaluator)}.
* *
* Uses a cost evaluator which uses the supplied property key to * Uses a cost evaluator which uses the supplied property key to
* represent the cost (values of type <bold>double</bold>). * represent the cost (values of type <bold>double</bold>).
* *
* @param expander the {@link PathExpander} to use for expanding * @param expander the {@link PathExpander} to use for expanding
* {@link Relationship}s for each {@link Path}. * {@link Relationship}s for each {@link Path}.
* @param stateFactory initial state for the traversal branches. * @param stateFactory initial state for the traversal branches.
Expand All @@ -412,10 +413,10 @@ public static PathFinder<WeightedPath> dijkstra( PathExpander expander,


/** /**
* See {@link #dijkstra(RelationshipExpander, CostEvaluator)}. * See {@link #dijkstra(RelationshipExpander, CostEvaluator)}.
* *
* Uses a cost evaluator which uses the supplied property key to * Uses a cost evaluator which uses the supplied property key to
* represent the cost (values of type <bold>double</bold>). * represent the cost (values of type <bold>double</bold>).
* *
* @param expander the {@link PathExpander} to use for expanding * @param expander the {@link PathExpander} to use for expanding
* {@link Relationship}s for each {@link Path}. * {@link Relationship}s for each {@link Path}.
* @param stateFactory initial state for the traversal branches. * @param stateFactory initial state for the traversal branches.
Expand Down
41 changes: 20 additions & 21 deletions community/graph-algo/src/main/java/org/neo4j/graphalgo/impl/path/ExactDepthPathFinder.java
View file
Expand Up @@ -19,13 +19,6 @@
*/ */
package org.neo4j.graphalgo.impl.path; package org.neo4j.graphalgo.impl.path;


import static org.neo4j.graphdb.traversal.Evaluators.atDepth;
import static org.neo4j.graphdb.traversal.Evaluators.toDepth;
import static org.neo4j.kernel.StandardExpander.toPathExpander;
import static org.neo4j.kernel.Traversal.bidirectionalTraversal;
import static org.neo4j.kernel.Traversal.traversal;
import static org.neo4j.kernel.Uniqueness.RELATIONSHIP_GLOBAL;

import org.neo4j.graphalgo.impl.util.LiteDepthFirstSelector; import org.neo4j.graphalgo.impl.util.LiteDepthFirstSelector;
import org.neo4j.graphdb.Node; import org.neo4j.graphdb.Node;
import org.neo4j.graphdb.PathExpander; import org.neo4j.graphdb.PathExpander;
Expand All @@ -35,6 +28,13 @@
import org.neo4j.graphdb.traversal.TraversalBranch; import org.neo4j.graphdb.traversal.TraversalBranch;
import org.neo4j.graphdb.traversal.TraversalDescription; import org.neo4j.graphdb.traversal.TraversalDescription;
import org.neo4j.graphdb.traversal.Traverser; import org.neo4j.graphdb.traversal.Traverser;
import org.neo4j.graphdb.traversal.Uniqueness;

import static org.neo4j.graphdb.traversal.Evaluators.atDepth;
import static org.neo4j.graphdb.traversal.Evaluators.toDepth;
import static org.neo4j.kernel.StandardExpander.toPathExpander;
import static org.neo4j.kernel.Traversal.bidirectionalTraversal;
import static org.neo4j.kernel.Traversal.traversal;


/** /**
* Tries to find paths in a graph from a start node to an end node where the * Tries to find paths in a graph from a start node to an end node where the
Expand All @@ -53,39 +53,38 @@ public class ExactDepthPathFinder extends TraversalPathFinder
private final PathExpander expander; private final PathExpander expander;
private final int onDepth; private final int onDepth;
private final int startThreshold; private final int startThreshold;
private final Uniqueness uniqueness;


public ExactDepthPathFinder( RelationshipExpander expander, int onDepth, public ExactDepthPathFinder( RelationshipExpander expander, int onDepth, int startThreshold, boolean allowLoops )
int startThreshold )
{ {
this( toPathExpander( expander ), onDepth, startThreshold ); this( toPathExpander( expander ), onDepth, startThreshold, allowLoops );
} }


public ExactDepthPathFinder( PathExpander expander, int onDepth, int startThreshold ) public ExactDepthPathFinder( PathExpander expander, int onDepth, int startThreshold, boolean allowLoops )
{ {
this.expander = expander; this.expander = expander;
this.onDepth = onDepth; this.onDepth = onDepth;
this.startThreshold = startThreshold; this.startThreshold = startThreshold;
this.uniqueness = allowLoops ? Uniqueness.RELATIONSHIP_GLOBAL : Uniqueness.NODE_PATH;
} }


@Override @Override
protected Traverser instantiateTraverser( Node start, Node end ) protected Traverser instantiateTraverser( Node start, Node end )
{ {
TraversalDescription side = traversal().breadthFirst().expand( expander ).uniqueness( RELATIONSHIP_GLOBAL ).order( TraversalDescription side =
new BranchOrderingPolicy() traversal().breadthFirst().uniqueness( uniqueness ).order( new BranchOrderingPolicy()
{ {
@Override
public BranchSelector create( TraversalBranch startSource, PathExpander expander ) public BranchSelector create( TraversalBranch startSource, PathExpander expander )
{ {
return new LiteDepthFirstSelector( startSource, return new LiteDepthFirstSelector( startSource, startThreshold, expander );
startThreshold, expander );
} }
} ); } );

return bidirectionalTraversal().startSide( side.expand( expander ).evaluator( toDepth( onDepth / 2 ) ) )
return bidirectionalTraversal() .endSide( side.expand( expander.reverse() ).evaluator( toDepth( onDepth - onDepth / 2 ) ) )
.startSide( side.evaluator( toDepth( onDepth/2 ) ) )
.endSide( side.evaluator( toDepth( onDepth-onDepth/2 ) ) )
.collisionEvaluator( atDepth( onDepth ) ) .collisionEvaluator( atDepth( onDepth ) )
// TODO Level side selector will make the traversal return wrong result, why? // TODO Level side selector will make the traversal return wrong result, why?
// .sideSelector( SideSelectorPolicies.LEVEL, onDepth ) // .sideSelector( SideSelectorPolicies.LEVEL, onDepth )
.traverse( start, end ); .traverse( start, end );
} }
} }

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