com.sparsity.dex.algorithms
Class WeakConnectivityDFS

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

public class WeakConnectivityDFS
extends WeakConnectivity

WeakConnectivityDFS class.

This class can be used to solve the problem of finding weakly connected components in an undirected graph or in a directed graph which will be considered as an undirected one.

It consists in finding components where every pair (u,v) of nodes contained in it has a path from u to v and from v to u. This implementation is based on the Depth-First Search (DFS) 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.

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

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

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

Constructor Summary
WeakConnectivityDFS(Session s)
          Creates a new instance of WeakConnectivityDFS.
 
Method Summary
 void addAllEdgeTypes()
          Allows connectivity through all edge types of the graph.
 void addAllNodeTypes()
          Allows connectivity through all node types of the graph.
 void addEdgeType(int t)
          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

WeakConnectivityDFS

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

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 weak 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 WeakConnectivity

addAllEdgeTypes

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

In a weak connectivity the edges can be used in Any direction. d[in] Edge direction.

Overrides:
addAllEdgeTypes in class WeakConnectivity

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 WeakConnectivity
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 WeakConnectivity

addEdgeType

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

In a weak connectivity the edges can be used in Any direction. d[in] Edge direction.

Overrides:
addEdgeType in class WeakConnectivity
Parameters:
t - [in] Edge type.

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