mxGraph 2.5.0.2


com.mxgraph.analysis
Class mxGraphAnalysis

java.lang.Object
  extended by com.mxgraph.analysis.mxGraphAnalysis

public class mxGraphAnalysis
extends Object

A singleton class that provides algorithms for graphs. Assume these variables for the following examples:
mxICostFunction cf = mxDistanceCostFunction(); Object[] v = graph.getChildVertices(graph.getDefaultParent()); Object[] e = graph.getChildEdges(graph.getDefaultParent()); mxGraphAnalysis mga = mxGraphAnalysis.getInstance();

Shortest Path (Dijkstra)

For example, to find the shortest path between the first and the second selected cell in a graph use the following code:

Object[] path = mga.getShortestPath(graph, from, to, cf, v.length, true);

Minimum Spanning Tree

This algorithm finds the set of edges with the minimal length that connect all vertices. This algorithm can be used as follows:
Prim
mga.getMinimumSpanningTree(graph, v, cf, true))
Kruskal
mga.getMinimumSpanningTree(graph, v, e, cf))

Connection Components

The union find may be used as follows to determine whether two cells are connected: boolean connected = uf.differ(vertex1, vertex2).

See Also:
mxICostFunction

Field Summary
protected static mxGraphAnalysis instance
          Holds the shared instance of this class.
 
Constructor Summary
protected mxGraphAnalysis()
           
 
Method Summary
protected  mxFibonacciHeap createPriorityQueue()
          Hook for subclassers to provide a custom fibonacci heap.
protected  mxUnionFind createUnionFind(Object[] v)
          Hook for subclassers to provide a custom union find structure.
 mxUnionFind getConnectionComponents(mxGraph graph, Object[] v, Object[] e)
          Returns a union find structure representing the connection components of G=(E,V).
static mxGraphAnalysis getInstance()
           
 Object[] getMinimumSpanningTree(mxGraph graph, Object[] v, mxICostFunction cf, boolean directed)
          Returns the minimum spanning tree (MST) for the graph defined by G=(E,V).
 Object[] getMinimumSpanningTree(mxGraph graph, Object[] v, Object[] e, mxICostFunction cf)
          Returns the minimum spanning tree (MST) for the graph defined by G=(E,V).
 Object[] getShortestPath(mxGraph graph, Object from, Object to, mxICostFunction cf, int steps, boolean directed)
          Returns the shortest path between two cells or their descendants represented as an array of edges in order of traversal.
static void setInstance(mxGraphAnalysis instance)
          Sets the shared instance of this class.
 mxCellState[] sort(mxCellState[] states, mxICostFunction cf)
          Returns a sorted set for cells with respect to cf.
 double sum(mxCellState[] states, mxICostFunction cf)
          Returns the sum of all cost for cells with respect to cf.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

instance

protected static mxGraphAnalysis instance
Holds the shared instance of this class.

Constructor Detail

mxGraphAnalysis

protected mxGraphAnalysis()
Method Detail

getInstance

public static mxGraphAnalysis getInstance()
Returns:
Returns the sharedInstance.

setInstance

public static void setInstance(mxGraphAnalysis instance)
Sets the shared instance of this class.

Parameters:
instance - The instance to set.

getShortestPath

public Object[] getShortestPath(mxGraph graph,
                                Object from,
                                Object to,
                                mxICostFunction cf,
                                int steps,
                                boolean directed)
Returns the shortest path between two cells or their descendants represented as an array of edges in order of traversal.
This implementation is based on the Dijkstra algorithm.

Parameters:
graph - The object that defines the graph structure
from - The source cell.
to - The target cell (aka sink).
cf - The cost function that defines the edge length.
steps - The maximum number of edges to traverse.
directed - If edge directions should be taken into account.
Returns:
Returns the shortest path as an alternating array of vertices and edges, starting with from and ending with to.
See Also:
createPriorityQueue()

getMinimumSpanningTree

public Object[] getMinimumSpanningTree(mxGraph graph,
                                       Object[] v,
                                       mxICostFunction cf,
                                       boolean directed)
Returns the minimum spanning tree (MST) for the graph defined by G=(E,V). The MST is defined as the set of all vertices with minimal lengths that forms no cycles in G.
This implementation is based on the algorihm by Prim-Jarnik. It uses O(|E|+|V|log|V|) time when used with a Fibonacci heap and a graph whith a double linked-list datastructure, as is the case with the default implementation.

Parameters:
graph - the object that describes the graph
v - the vertices of the graph
cf - the cost function that defines the edge length
Returns:
Returns the MST as an array of edges
See Also:
createPriorityQueue()

getMinimumSpanningTree

public Object[] getMinimumSpanningTree(mxGraph graph,
                                       Object[] v,
                                       Object[] e,
                                       mxICostFunction cf)
Returns the minimum spanning tree (MST) for the graph defined by G=(E,V). The MST is defined as the set of all vertices with minimal lenths that forms no cycles in G.
This implementation is based on the algorihm by Kruskal. It uses O(|E|log|E|)=O(|E|log|V|) time for sorting the edges, O(|V|) create sets, O(|E|) find and O(|V|) union calls on the union find structure, thus yielding no more than O(|E|log|V|) steps. For a faster implementatin

Parameters:
graph - The object that contains the graph.
v - The vertices of the graph.
e - The edges of the graph.
cf - The cost function that defines the edge length.
Returns:
Returns the MST as an array of edges.
See Also:
getMinimumSpanningTree(mxGraph, Object[], mxICostFunction, boolean), createUnionFind(Object[])

getConnectionComponents

public mxUnionFind getConnectionComponents(mxGraph graph,
                                           Object[] v,
                                           Object[] e)
Returns a union find structure representing the connection components of G=(E,V).

Parameters:
graph - The object that contains the graph.
v - The vertices of the graph.
e - The edges of the graph.
Returns:
Returns the connection components in G=(E,V)
See Also:
createUnionFind(Object[])

sort

public mxCellState[] sort(mxCellState[] states,
                          mxICostFunction cf)
Returns a sorted set for cells with respect to cf.

Parameters:
states - the cell states to sort
cf - the cost function that defines the order
Returns:
Returns an ordered set of cells wrt. cf

sum

public double sum(mxCellState[] states,
                  mxICostFunction cf)
Returns the sum of all cost for cells with respect to cf.

Parameters:
states - the cell states to use for the sum
cf - the cost function that defines the costs
Returns:
Returns the sum of all cell cost

createUnionFind

protected mxUnionFind createUnionFind(Object[] v)
Hook for subclassers to provide a custom union find structure.

Parameters:
v - the array of all elements
Returns:
Returns a union find structure for v

createPriorityQueue

protected mxFibonacciHeap createPriorityQueue()
Hook for subclassers to provide a custom fibonacci heap.


mxGraph 2.5.0.2


Copyright (c) 2010 Gaudenz Alder, David Benson. All rights reserved.