com.sparsity.dex.algorithms
Class StrongConnectivityGabow

java.lang.Object
  extended by com.sparsity.dex.algorithms.Connectivity
      extended by com.sparsity.dex.algorithms.StrongConnectivity
          extended by com.sparsity.dex.algorithms.StrongConnectivityGabow
All Implemented Interfaces:
java.io.Closeable

public class StrongConnectivityGabow
extends StrongConnectivity

This class can be used to solve the problem of finding strongly connected components in a directed graph.

It consists in finding components where every pair (u,v) of nodes contained in it has a path from u to v using the specified direction for each edge type. This implementation is based on the Gabow algorithm.

It is possible to set some restrictions after constructing a new instance of this class and before running it in order to limit the results. Those restrictions are:

(i) The set of edge types which will be navigated through while traversing the graph. The method is AddEdgeType for adding one edge type and AddAllEdgeTypes for adding all edge types with a specified direction.

(ii) The set of node types which will be navigated through while traversing the graph. The method is AddNodeType for adding one node type and AddAllNodeTypes for adding all node types.

For each instance of this class, it is only allowed to run the algorithm once.

After the execution, we can retrieve the results stored in an instance of the class ConnectedComponents using the GetConnectedComponents() method.

NOTE: It is required to indicate the set of edge types and node types before running this algorithm.

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

Constructor Summary
StrongConnectivityGabow(Session s)
          Creates a new instance of StrongConnectivityGabow.
 
Method Summary
 void addAllEdgeTypes(EdgesDirection d)
          Allows connectivity through all edge types of the graph.
 void addAllNodeTypes()
          Allows connectivity through all node types of the graph.
 void addEdgeType(int t, EdgesDirection d)
          Allows connectivity through edges of the given type.
 void addNodeType(int t)
          Allows connectivity through nodes of the given type.
 void excludeEdges(Objects edges)
          Set which edges can't be used.
 void excludeNodes(Objects nodes)
          Set which nodes can't be used.
 ConnectedComponents getConnectedComponents()
          Returns the results generated by the execution of the algorithm.
 void run()
          Executes the algorithm.
 void setMaterializedAttribute(java.lang.String attributeName)
          Creates a new common attribute type for all node types in the graph in order to store, persistently, the results related to the connected components found while executing this algorithm.
 
Methods inherited from class com.sparsity.dex.algorithms.Connectivity
close, isClosed
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

StrongConnectivityGabow

public StrongConnectivityGabow(Session s)
Creates a new instance of StrongConnectivityGabow.

After creating this instance is required to indicate the set of edge types and the set of node types which will be navigated through while traversing the graph in order to find the strong connected components.

Parameters:
s - [in] Session to get the graph from and calculate the connectivity
Method Detail

addAllNodeTypes

public void addAllNodeTypes()
Allows connectivity through all node types of the graph.

Overrides:
addAllNodeTypes in class StrongConnectivity

addAllEdgeTypes

public void addAllEdgeTypes(EdgesDirection d)
Allows connectivity through all edge types of the graph.

Overrides:
addAllEdgeTypes in class StrongConnectivity
Parameters:
d - [in] Edge direction.

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

run

public void run()
Executes the algorithm.

Overrides:
run in class StrongConnectivity

addEdgeType

public void addEdgeType(int t,
                        EdgesDirection d)
Allows connectivity through edges of the given type.

Overrides:
addEdgeType in class StrongConnectivity
Parameters:
t - [in] Edge type.
d - [in] Edge direction.

setMaterializedAttribute

public void setMaterializedAttribute(java.lang.String attributeName)
Creates a new common attribute type for all node types in the graph in order to store, persistently, the results related to the connected components found while executing this algorithm.

Whenever the user wants to retrieve the results, even when the graph has been closed and opened again, it is only necessary to create a new instance of the class ConnectedComponents indicating the graph and the name of the common attribute type which stores the results. This instance will have all the information related to the connected components found in the moment of the execution of the algorithm that stored this data.

It is possible to run the algorithm without specifying this parameter in order to avoid materializing the results of the execution.

Overrides:
setMaterializedAttribute in class StrongConnectivity
Parameters:
attributeName - [in] The name of the common attribute type for all node types in the graph which will store persistently the results generated by the execution of the algorithm.

addNodeType

public void addNodeType(int t)
Allows connectivity through nodes of the given type.

Overrides:
addNodeType in class StrongConnectivity
Parameters:
t - null

getConnectedComponents

public ConnectedComponents getConnectedComponents()
Returns the results generated by the execution of the algorithm.

These results contain information related to the connected components found as the number of different components, the set of nodes contained in each component or many other data.

Overrides:
getConnectedComponents in class StrongConnectivity
Returns:
Returns an instance of the class ConnectedComponents which contain information related to the connected components found.

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