weka.clusterers
Class FarthestFirst

java.lang.Object
  |
  +--weka.clusterers.Clusterer
        |
        +--weka.clusterers.FarthestFirst

All Implemented Interfaces:

java.lang.Cloneable, OptionHandler, java.io.Serializable

public class FarthestFirst

extends Clusterer

implements OptionHandler

Implements the "Farthest First Traversal Algorithm" by Hochbaum and Shmoys 1985: A best possible heuristic for the k-center problem, Mathematics of Operations Research, 10(2):180-184, as cited by Sanjoy Dasgupta "performance guarantees for hierarchical clustering", colt 2002, sydney works as a fast simple approximate clusterer modelled after SimpleKMeans, might be a useful initializer for it Valid options are:

-N
Specify the number of clusters to generate.

-S
Specify random number seed.

Version:

$Revision: 1.1 $

Author:

Bernhard Pfahringer (bernhard@cs.waikato.ac.nz)

See Also:

Clusterer, OptionHandler, Serialized Form

Constructor Summary

FarthestFirst()

Method Summary

void	buildClusterer(Instances data) Generates a clusterer.
int	clusterInstance(Instance instance) Classifies a given instance.
int	getNumClusters() gets the number of clusters to generate
java.lang.String[]	getOptions() Gets the current settings of FarthestFirst
int	getSeed() Get the random number seed
java.lang.String	globalInfo() Returns a string describing this clusterer
java.util.Enumeration	listOptions() Returns an enumeration describing the available options..
static void	main(java.lang.String[] argv) Main method for testing this class.
int	numberOfClusters() Returns the number of clusters.
java.lang.String	numClustersTipText() Returns the tip text for this property
java.lang.String	seedTipText() Returns the tip text for this property
void	setNumClusters(int n) set the number of clusters to generate
void	setOptions(java.lang.String[] options) Parses a given list of options.
void	setSeed(int s) Set the random number seed
java.lang.String	toString() return a string describing this clusterer

Methods inherited from class weka.clusterers.Clusterer

distributionForInstance, forName, makeCopies

Methods inherited from class java.lang.Object

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

Constructor Detail

FarthestFirst

public FarthestFirst()

Method Detail

globalInfo

public java.lang.String globalInfo()

Returns a string describing this clusterer

Returns:

a description of the evaluator suitable for displaying in the explorer/experimenter gui

buildClusterer

public void buildClusterer(Instances data)
                    throws java.lang.Exception

Generates a clusterer. Has to initialize all fields of the clusterer that are not being set via options.

Specified by:

buildClusterer in class Clusterer

Parameters:

data - set of instances serving as training data

Throws:

java.lang.Exception - if the clusterer has not been generated successfully

clusterInstance

public int clusterInstance(Instance instance)
                    throws java.lang.Exception

Classifies a given instance.

Overrides:

clusterInstance in class Clusterer

Parameters:

instance - the instance to be assigned to a cluster

Returns:

the number of the assigned cluster as an integer if the class is enumerated, otherwise the predicted value

Throws:

java.lang.Exception - if instance could not be classified successfully

numberOfClusters

public int numberOfClusters()
                     throws java.lang.Exception

Returns the number of clusters.

Specified by:

numberOfClusters in class Clusterer

Returns:

the number of clusters generated for a training dataset.

Throws:

java.lang.Exception - if number of clusters could not be returned successfully

listOptions

public java.util.Enumeration listOptions()

Returns an enumeration describing the available options..

Valid options are:

-N
Specify the number of clusters to generate. If omitted, FarthestFirst will use cross validation to select the number of clusters automatically.

-S
Specify random number seed.

Specified by:

listOptions in interface OptionHandler

Returns:

an enumeration of all the available options.

numClustersTipText

public java.lang.String numClustersTipText()

Returns the tip text for this property

Returns:

tip text for this property suitable for displaying in the explorer/experimenter gui

setNumClusters

public void setNumClusters(int n)

set the number of clusters to generate

Parameters:

n - the number of clusters to generate

getNumClusters

public int getNumClusters()

gets the number of clusters to generate

Returns:

the number of clusters to generate

seedTipText

public java.lang.String seedTipText()

Returns the tip text for this property

Returns:

tip text for this property suitable for displaying in the explorer/experimenter gui

setSeed

public void setSeed(int s)

Set the random number seed

Parameters:

s - the seed

getSeed

public int getSeed()

Get the random number seed

Returns:

the seed

setOptions

public void setOptions(java.lang.String[] options)
                throws java.lang.Exception

Parses a given list of options.

Specified by:

setOptions in interface OptionHandler

Parameters:

options - the list of options as an array of strings

Throws:

java.lang.Exception - if an option is not supported

getOptions

public java.lang.String[] getOptions()

Gets the current settings of FarthestFirst

Specified by:

getOptions in interface OptionHandler

Returns:

an array of strings suitable for passing to setOptions()

toString

public java.lang.String toString()

return a string describing this clusterer

Overrides:

toString in class java.lang.Object

Returns:

a description of the clusterer as a string

main

public static void main(java.lang.String[] argv)

Main method for testing this class.

Parameters:

argv - should contain the following arguments:

-t training file [-N number of clusters]