org.graphstream.algorithm

Class AbstractSpanningTree

java.lang.Object

org.graphstream.algorithm.AbstractSpanningTree

All Implemented Interfaces:

Algorithm, SpanningTree

Direct Known Subclasses:

Dijkstra, Kruskal

public abstract class AbstractSpanningTree
extends Object
implements SpanningTree

Base for spanning tree algorithms.

The result is stored in an edge attribute which name is defined by flagAttribute and value is flagOn if the edge is in the tree or flagOff if not. If flagAttribute is null nothing is stored in the edges. If flagOn is null edges in the tree are not tagged. If flagOff is null edges out of the tree are not tagged.

Creating a spanning tree algorithm

Spanning tree algorithms have to extend this class and to implements the makeTree() and getTreeEdgesIterator() methods. edgeOn(Edge) and edgeOff(Edge) methods have to be used to properly tag edges.

A call to compute reset the values of edges attribute. Then a call to makeTree() is made.

Highlight the spanning tree in viewer

Using the CSS, it is possible to highlight the spanning tree result using classes. Considering two css edge classes have been defined in the CSS, for example :

 edge .in {
         size: 3px;
   fill-color: black;
 }
 
 edge .notin {
   size: 2px;
   fill-color: gray;
 }
 

You can tell the algorithm to set up the value of the "ui.class" attribute of edges to "in" when the edge is in the tree or "notin" when edge is not in the tree.

This can be done by setting the flagAttribute of the algorithm using the setter setFlagAttribute(String) and the flag values flagOn and flagOff with setFlagOn(Object) and setFlagOff(Object) setters.

 Graph graph = ...;
 AbstractSpanningTree sp = ...;
 
 ...
 
 sp.setFlagAttribute("ui.class");
 sp.setFlagOn("in");
 sp.setFlagOff("notin");
 
 sp.init(graph);
 sp.compute();
 
 graph.display();
 
 ..
 

Constructor Summary

Constructors

Constructor and Description
AbstractSpanningTree() Create a new SpanningTree algorithm.
AbstractSpanningTree(String flagAttribute) Create a new SpanningTree algorithm.
AbstractSpanningTree(String flagAttribute, Object flagOn, Object flagOff) Create a new SpanningTree algorithm.

Method Summary

Methods

Modifier and Type	Method and Description
void	clear() Removes the tags of all edges.
void	compute() Run the algorithm.
String	getFlagAttribute() Get key attribute which will be used to set if edges are in the spanning tree, or not.
Object	getFlagOff() Get value used to set that an edge is not in the spanning tree.
Object	getFlagOn() Get value used to set that an edge is in the spanning tree.
<T extends org.graphstream.graph.Edge> Iterable<T>	getTreeEdges() Iterable view of the spanning tree edges.
abstract <T extends org.graphstream.graph.Edge> Iterator<T>	getTreeEdgesIterator() An iterator on the tree edges.
void	init(org.graphstream.graph.Graph graph) Initialization of the algorithm.
void	setFlagAttribute(String flagAttribute) Set the flag attribute.
void	setFlagOff(Object flagOff) Set value used to set that an edge is not in the spanning tree.
void	setFlagOn(Object flagOn) Set value used to set that an edge is in the spanning tree.

Methods inherited from class java.lang.Object

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

Constructor Detail

AbstractSpanningTree

public AbstractSpanningTree()

Create a new SpanningTree algorithm. By default edges are not tagged.

AbstractSpanningTree

public AbstractSpanningTree(String flagAttribute)

Create a new SpanningTree algorithm. Default flag attribute values are true for edges in the tree and false for the remaining edges.

Parameters:

flagAttribute - attribute used to compare edges

AbstractSpanningTree

public AbstractSpanningTree(String flagAttribute,
                    Object flagOn,
                    Object flagOff)

Create a new SpanningTree algorithm.

Parameters:

flagAttribute - attribute used to set if an edge is in the spanning tree

flagOn - value of the flagAttribute if edge is in the spanning tree

flagOff - value of the flagAttribute if edge is not in the spanning tree

Method Detail

getFlagAttribute

public String getFlagAttribute()

Description copied from interface: SpanningTree

Get key attribute which will be used to set if edges are in the spanning tree, or not.

Specified by:

getFlagAttribute in interface SpanningTree

Returns:

flag attribute

setFlagAttribute

public void setFlagAttribute(String flagAttribute)

Description copied from interface: SpanningTree

Set the flag attribute.

Specified by:

setFlagAttribute in interface SpanningTree

Parameters:

flagAttribute - New attribute used. If null edges are not tagged.

getFlagOn

public Object getFlagOn()

Description copied from interface: SpanningTree

Get value used to set that an edge is in the spanning tree.

Specified by:

getFlagOn in interface SpanningTree

Returns:

on value

setFlagOn

public void setFlagOn(Object flagOn)

Description copied from interface: SpanningTree

Set value used to set that an edge is in the spanning tree.

Specified by:

setFlagOn in interface SpanningTree

Parameters:

flagOn - on value. If null edges in the tree are not tagged.

getFlagOff

public Object getFlagOff()

Description copied from interface: SpanningTree

Get value used to set that an edge is not in the spanning tree.

Specified by:

getFlagOff in interface SpanningTree

Returns:

off value

setFlagOff

public void setFlagOff(Object flagOff)

Description copied from interface: SpanningTree

Set value used to set that an edge is not in the spanning tree.

Specified by:

setFlagOff in interface SpanningTree

getTreeEdgesIterator

public abstract <T extends org.graphstream.graph.Edge> Iterator<T> getTreeEdgesIterator()

Description copied from interface: SpanningTree

An iterator on the tree edges.

Specified by:

getTreeEdgesIterator in interface SpanningTree

Returns:

An iterator on the tree edges

getTreeEdges

public <T extends org.graphstream.graph.Edge> Iterable<T> getTreeEdges()

Description copied from interface: SpanningTree

Iterable view of the spanning tree edges. This implementation uses SpanningTree.getTreeEdgesIterator().

Specified by:

getTreeEdges in interface SpanningTree

Returns:

Iterable view of the tree edges.

clear

public void clear()

Description copied from interface: SpanningTree

Removes the tags of all edges. Use this method to save memory if the spanning tree is used no more.

Specified by:

clear in interface SpanningTree

init

public void init(org.graphstream.graph.Graph graph)

Description copied from interface: Algorithm

Initialization of the algorithm. This method has to be called before the Algorithm.compute() method to initialize or reset the algorithm according to the new given graph.

Specified by:

init in interface Algorithm

Parameters:

graph - The graph this algorithm is using.

compute

public void compute()

Description copied from interface: Algorithm

Run the algorithm. The Algorithm.init(Graph) method has to be called before computing.

Specified by:

compute in interface Algorithm

See Also:

Algorithm.init(Graph)