org.graphstream.algorithm

Class Eccentricity

java.lang.Object

org.graphstream.algorithm.Eccentricity

All Implemented Interfaces:

Algorithm

public class Eccentricity
extends Object
implements Algorithm

Compute the eccentricity of a connected graph.

In a graph G, if d(u,v) is the shortest length between two nodes u and v (ie the number of edges of the shortest path) let e(u) be the d(u,v) such that v is the farthest of u. Eccentricity of a graph G is a subgraph induced by vertices u with minimum e(u).

Requirements

This algorithm needs that APSP algorithm has been computed before its own computation.

Example

 import java.io.StringReader;
 import java.io.IOException;
 
 import org.graphstream.algorithm.Centroid;
 import org.graphstream.graph.Graph;
 import org.graphstream.graph.implementations.DefaultGraph;
 import org.graphstream.stream.file.FileSourceDGS;
 
 //                     +--- E
 // A --- B --- C -- D -|--- F
 //                     +--- G
 
 public class EccentriciyTest {
        static String my_graph = "DGS004\n" + "my 0 0\n" + "an A \n" + "an B \n"
                        + "an C \n" + "an D \n" + "an E \n" + "an F \n" + "an G \n"
                        + "ae AB A B \n" + "ae BC B C \n" + "ae CD C D \n" + "ae DE D E \n"
                        + "ae DF D F \n" + "ae DG D G \n";
 
        public static void main(String[] args) throws IOException {
                Graph graph = new DefaultGraph("Centroid Test");
                StringReader reader = new StringReader(my_graph);
 
                FileSourceDGS source = new FileSourceDGS();
                source.addSink(graph);
                source.readAll(reader);
 
                APSP apsp = new APSP();
                apsp.init(graph);
                apsp.compute();
 
                Eccentricity eccentricity = new Eccentricity();
                eccentricity.init(graph);
                eccentricity.compute();
 
                for (Node n : graph.getEachNode()) {
                        Boolean in = n.getAttribute("eccentricity");
 
                        System.out.printf("%s is%s in the eccentricity.\n", n.getId(), in ? ""
                                        : " not");
                }
 
                // Output will be :
                //
                // A is not in the eccentricity
                // B is not in the eccentricity
                // C is in the eccentricity
                // D is not in the eccentricity
                // E is not in the eccentricity
                // F is not in the eccentricity
                // G is not in the eccentricity
        }
 }
 

See Also:

APSP.APSPInfo

Computational Complexity :

O(n2)

Scientific Reference :

F. Harary, Graph Theory. Westview Press, Oct. 1969. [Online]. Available: http://www.amazon.com/exec/obidos/ redirect?tag=citeulike07-20\&path=ASIN/0201410338

Constructor Summary

Constructors

Constructor and Description
Eccentricity() Build a new eccentricity algorithm with default parameters.
Eccentricity(String eccentricityAttribute) Build a new eccentricity algorithm, specifying the attribute name of the computation result
Eccentricity(String eccentricityAttribute, Object isInEccentricity, Object isNotInEccentricity) Build a new eccentricity as in Eccentricity(String) but specifying values of eccentricity membership.
Eccentricity(String eccentricityAttribute, Object isInEccentricity, Object isNotInEccentricity, String apspInfoAttribute) Build a new eccentricity algorithm as in Eccentricity(String, Object, Object) but specifying the name of the attribute where the APSP informations are stored.

Method Summary

Methods

Modifier and Type	Method and Description
void	compute() Run the algorithm.
String	getAPSPInfoAttribute() Get the APSP info attribute name.
String	getEccentricityAttribute() Get the name of the attribute where computation result is stored.
Object	getIsInEccentricityValue() Get the value of the eccentricity attribute when element is in the eccentricity.
Object	getIsNotInEccentricityValue() Get the value of the eccentricity attribute when element is not in the eccentricity.
void	init(org.graphstream.graph.Graph graph) Initialization of the algorithm.
void	setAPSPInfoAttribute(String attribute) Set the APSP info attribute name.
void	setEccentricityAttribute(String eccentricityAttribute) Set the name of the attribute where computation result is stored.
void	setIsInEccentricityValue(Object value) Set the value of the eccentricity attribute when element is in the eccentricity.
void	setIsNotInEccentricityValue(Object value) Set the value of the eccentricity attribute when element is not in the eccentricity.

Methods inherited from class java.lang.Object

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

Constructor Detail

Eccentricity

public Eccentricity()

Build a new eccentricity algorithm with default parameters.

Eccentricity

public Eccentricity(String eccentricityAttribute)

Build a new eccentricity algorithm, specifying the attribute name of the computation result

Parameters:

eccentricityAttribute - attribute name of the computation result.

Eccentricity

public Eccentricity(String eccentricityAttribute,
            Object isInEccentricity,
            Object isNotInEccentricity)

Build a new eccentricity as in Eccentricity(String) but specifying values of eccentricity membership.

Parameters:

eccentricityAttribute - attribute name of the computation result.

isInEccentricity - the value of elements eccentricity attribute when this element is in the eccentricity.

isNotInEccentricity - the value of elements eccentricity attribute when this element is not in the eccentricity.

Eccentricity

public Eccentricity(String eccentricityAttribute,
            Object isInEccentricity,
            Object isNotInEccentricity,
            String apspInfoAttribute)

Build a new eccentricity algorithm as in Eccentricity(String, Object, Object) but specifying the name of the attribute where the APSP informations are stored.

Parameters:

eccentricityAttribute - attribute name of the computation result.

isInEccentricity - the value of elements eccentricity attribute when this element is in the eccentricity.

isNotInEccentricity - the value of elements eccentricity attribute when this element is not in the eccentricity.

apspInfoAttribute - the name of the attribute where the APSP informations are stored

Method Detail

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)

getAPSPInfoAttribute

public String getAPSPInfoAttribute()

Get the APSP info attribute name.

Returns:

the name of the attribute where the APSP informations are stored.

setAPSPInfoAttribute

public void setAPSPInfoAttribute(String attribute)

Set the APSP info attribute name.

Parameters:

attribute - the name of the attribute where the APSP informations are stored.

getIsInEccentricityValue

public Object getIsInEccentricityValue()

Get the value of the eccentricity attribute when element is in the eccentricity. Default value is Boolean.TRUE.

Returns:

the value of elements eccentricity attribute when this element is in the eccentricity.

setIsInEccentricityValue

public void setIsInEccentricityValue(Object value)

Set the value of the eccentricity attribute when element is in the eccentricity. On computation, this value is used to set the eccentricity attribute.

Parameters:

value - the value of elements eccentricity attribute when this element is in the eccentricity.

getIsNotInEccentricityValue

public Object getIsNotInEccentricityValue()

Get the value of the eccentricity attribute when element is not in the eccentricity. Default value is Boolean.FALSE.

Returns:

the value of elements eccentricity attribute when this element is not in the eccentricity.

setIsNotInEccentricityValue

public void setIsNotInEccentricityValue(Object value)

Set the value of the eccentricity attribute when element is not in the eccentricity. On computation, this value is used to set the eccentricity attribute.

Parameters:

value - the value of elements eccentricity attribute when this element is not in the eccentricity.

getEccentricityAttribute

public String getEccentricityAttribute()

Get the name of the attribute where computation result is stored. Value of this attribute can be getIsInEccentricityValue() if the element is in the eccentricity, getIsNotInEccentricityValue() else.

Returns:

the eccentricity attribute name.

setEccentricityAttribute

public void setEccentricityAttribute(String eccentricityAttribute)

Set the name of the attribute where computation result is stored.

Parameters:

eccentricityAttribute - the name of the element attribute where computation result is stored.