com.sparsity.sparksee.algorithms

Class SinglePairShortestPathDijkstra

java.lang.Object

com.sparsity.sparksee.algorithms.ShortestPath

com.sparsity.sparksee.algorithms.SinglePairShortestPath

com.sparsity.sparksee.algorithms.SinglePairShortestPathDijkstra

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable

public class SinglePairShortestPathDijkstra
extends SinglePairShortestPath

SinglePairShortestPathDijkstra class.

It solves the single-pair shortest path problem using a Dijkstra-based implementation.

It is a weighted algorithm, so it takes into account the cost of the edges to compute a minimum-cost shortest path. That is, the user may set for each edge type which attribute should be used to retrieve the cost of the edge. If no attribute is given for an edge type, this will assume the edge has a fixed cost (the default is 1). Only numerical attribute can be set as weight attributes (that is Long, Integer or Double attributes are allowed).

Check out the 'Algorithms' section in the SPARKSEE User Manual for more details on this.

Author:

Sparsity Technologies http://www.sparsity-technologies.com

Constructor Summary

Constructors

Constructor and Description
SinglePairShortestPathDijkstra(Session session, long src, long dst) Creates a new instance.

Method Summary

Modifier and Type	Method and Description
void	addAllEdgeTypes(EdgesDirection dir) Allows for traversing all edge types of the graph.
void	addAllNodeTypes() Allows for traversing all node types of the graph.
void	addEdgeType(int type, EdgesDirection dir) Allows for traversing edges of the given type.
void	addNodeType(int type) Allows for traversing nodes of the given type.
void	addWeightedEdgeType(int type, EdgesDirection dir, int attr) Allows for traversing edges of the given type using the given attribute as the weight.
void	excludeEdges(Objects edges) Set which edges can't be used.
void	excludeNodes(Objects nodes) Set which nodes can't be used.
boolean	exists() Returns TRUE If a path exists or FALSE otherwise.
double	getCost() Gets the cost of the shortest path.
OIDList	getPathAsEdges() Gets the shortest path between the source node and the destination node as an ordered set of edges.
OIDList	getPathAsNodes() Gets the shortest path between the source node and the destination node as an ordered set of nodes.
void	run() Executes the algorithm.
void	setDynamicEdgeCostCallback(SinglePairShortestPathDijkstraDynamicCost dynCostCalculator) Set a class callback to dynamically calculate the cost of the edges.
void	setMaximumHops(int maxhops) Sets the maximum hops restriction.
void	setUnweightedEdgeCost(double weight) Sets the weight assigned to the unweighted edges.

Methods inherited from class com.sparsity.sparksee.algorithms.ShortestPath

close, isClosed

Methods inherited from class java.lang.Object

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

Constructor Detail

SinglePairShortestPathDijkstra

public SinglePairShortestPathDijkstra(Session session,
                                      long src,
                                      long dst)

Creates a new instance.

Parameters:

session - [in] Session to get the graph from and perform traversal.

src - [in] Source node.

dst - [dst] Destination node.

Method Detail

excludeNodes

public void excludeNodes(Objects nodes)

Set which nodes can't be used.

This will replace any previously specified set of excluded nodes. Should only be used to exclude the usage of specific nodes from allowed node types because it's less efficient than not allowing a node type.

Overrides:

excludeNodes in class SinglePairShortestPath

Parameters:

nodes - [in] A set of node identifiers that must be kept intact until the destruction of the class.

getCost

public double getCost()

Gets the cost of the shortest path.

The cost is the sum of the weights of the edges in the shortest path.

Overrides:

getCost in class SinglePairShortestPath

Returns:

The cost of the shortest path.

run

public void run()

Executes the algorithm.

Overrides:

run in class SinglePairShortestPath

addAllEdgeTypes

public void addAllEdgeTypes(EdgesDirection dir)

Allows for traversing all edge types of the graph.

Overrides:

addAllEdgeTypes in class SinglePairShortestPath

Parameters:

dir - [in] Edge direction.

excludeEdges

public void excludeEdges(Objects edges)

Set which edges can't be used.

This will replace any previously specified set of excluded edges. Should only be used to exclude the usage of specific edges from allowed edge types because it's less efficient than not allowing an edge type.

Overrides:

excludeEdges in class SinglePairShortestPath

Parameters:

edges - [in] A set of edge identifiers that must be kept intact until the destruction of the class.

addEdgeType

public void addEdgeType(int type,
                        EdgesDirection dir)

Allows for traversing edges of the given type.

Overrides:

addEdgeType in class SinglePairShortestPath

Parameters:

type - [in] Edge type.

dir - [in] Edge direction.

setUnweightedEdgeCost

public void setUnweightedEdgeCost(double weight)

Sets the weight assigned to the unweighted edges.

All the edges from the types added without an explicit weight attribute will get this weight. The default weight for this edges is 1.

Parameters:

weight - [in] The weight value for unweighted edges.

getPathAsNodes

public OIDList getPathAsNodes()

Gets the shortest path between the source node and the destination node as an ordered set of nodes.

Overrides:

getPathAsNodes in class SinglePairShortestPath

Returns:

Ordered set of node identifiers.

setDynamicEdgeCostCallback

public void setDynamicEdgeCostCallback(SinglePairShortestPathDijkstraDynamicCost dynCostCalculator)

Set a class callback to dynamically calculate the cost of the edges.

The callback can be set to NULL (the default) to use the normal attribute based cost weights. The given class must be kept alive by the user for as long as the algorithm is running.

Parameters:

dynCostCalculator - [in] Class callback to calculate the edge costs

addNodeType

public void addNodeType(int type)

Allows for traversing nodes of the given type.

Overrides:

addNodeType in class SinglePairShortestPath

Parameters:

type - null

exists

public boolean exists()

Returns TRUE If a path exists or FALSE otherwise.

Overrides:

exists in class SinglePairShortestPath

getPathAsEdges

public OIDList getPathAsEdges()

Gets the shortest path between the source node and the destination node as an ordered set of edges.

Overrides:

getPathAsEdges in class SinglePairShortestPath

Returns:

Ordered set of edge identifiers.

addWeightedEdgeType

public void addWeightedEdgeType(int type,
                                EdgesDirection dir,
                                int attr)

Allows for traversing edges of the given type using the given attribute as the weight.

Parameters:

type - [in] Edge type.

dir - [in] Edge direction.

attr - [in] Attribute to be used as the weight. It must be a global attribute or an attribute of the given edge type.

setMaximumHops

public void setMaximumHops(int maxhops)

Sets the maximum hops restriction.

All paths longer than the maximum hops restriction will be ignored.

Overrides:

setMaximumHops in class SinglePairShortestPath

Parameters:

maxhops - [in] The maximum hops restriction. It must be positive or zero. Zero, the default value, means unlimited.

addAllNodeTypes

public void addAllNodeTypes()

Allows for traversing all node types of the graph.

Overrides:

addAllNodeTypes in class SinglePairShortestPath