com.sparsity.sparksee.algorithms
Class SinglePairShortestPathDijkstra

java.lang.Object
  extended by com.sparsity.sparksee.algorithms.ShortestPath
      extended by com.sparsity.sparksee.algorithms.SinglePairShortestPath
          extended by com.sparsity.sparksee.algorithms.SinglePairShortestPathDijkstra
All Implemented Interfaces:
java.io.Closeable

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
SinglePairShortestPathDijkstra(Session session, long src, long dst)
          Creates a new instance.
 
Method Summary
 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 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

exists

public boolean exists()
Returns TRUE If a path exists or FALSE otherwise.

Overrides:
exists in class SinglePairShortestPath

addNodeType

public void addNodeType(int type)
Allows for traversing nodes of the given type.

Overrides:
addNodeType in class SinglePairShortestPath
Parameters:
type - null

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.

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.

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.

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.

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.

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.

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.

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.

addAllNodeTypes

public void addAllNodeTypes()
Allows for traversing all node types of the graph.

Overrides:
addAllNodeTypes in class SinglePairShortestPath

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.

run

public void run()
Executes the algorithm.

Overrides:
run in class SinglePairShortestPath

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.