com.codemelon.graph.graph

Class Transposer<T extends Vertex,U extends Vertex>

java.lang.Object

com.codemelon.graph.graph.Transposer<T,U>

public class Transposer<T extends Vertex,U extends Vertex>
extends java.lang.Object

Utility class for transposing a graph. The type parameter T specifies the type of the vertices in the original graph, and the type U specifies the type of vertices in the transpose graph created by the transposer object. These 2 types will often be the same but do not have to be. The contract of the transposer is:

1. to produce a vertex of type U corresponding to each vertex in the input graph, and
2. to create an edge in the new graph whose tail corresponds to the head and whose head corresponds to the tail of the respective edge in the input graph

No satellite data is preserved by the transpose operation. It must be set in subsequent operations on the transpose graph.

Constructor Summary

Constructors

Constructor and Description
Transposer(AbstractGraph<T> graph, VertexFactory<U> vertexFactory, GraphFactory<U> graphFactory) Creates a transpose graph, which can be retrieved as needed through the getTransposeGraph() method, and a HashMap from the vertices of the original graph to the corresponding vertices of the transpose graph.

Method Summary

Methods

Modifier and Type	Method and Description
AbstractGraph<U>	getTransposeGraph() Returns the transpose of the original graph
java.util.Map<T,U>	getVertexMap() Returns a mapping in which the keys are the vertices of the original graph and the values are the corresponding vertices in the transpose graph.

Methods inherited from class java.lang.Object

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

Constructor Detail

Transposer

public Transposer(AbstractGraph<T> graph,
          VertexFactory<U> vertexFactory,
          GraphFactory<U> graphFactory)

Creates a transpose graph, which can be retrieved as needed through the getTransposeGraph() method, and a HashMap from the vertices of the original graph to the corresponding vertices of the transpose graph. Vertex and edge data (color, distance, discoveryTime, etc.) are not copied into the transpose graph. Satellite data can be set accordingly using the vertex mapping created during the transpose operation.

Parameters:

graph - graph for which the transpose is to be created.

vertexFactory - factory method used to create vertices in the transpose graph

Method Detail

getVertexMap

public java.util.Map<T,U> getVertexMap()

Returns a mapping in which the keys are the vertices of the original graph and the values are the corresponding vertices in the transpose graph. The mapping is created only when the transpose() method is called. If transpose() has not been called, this method will return null.

Returns:

a HashMap from vertices in the original graph to vertices in the transpose graph, or null, if transpose() has not yet been called.

getTransposeGraph

public AbstractGraph<U> getTransposeGraph()

Returns the transpose of the original graph

Returns:

transpose of the original graph