de.lmu.ifi.dbs.elki.math.linearalgebra.pca
Class SignificantEigenPairFilter

java.lang.Object
  de.lmu.ifi.dbs.elki.logging.AbstractLoggable
      de.lmu.ifi.dbs.elki.utilities.optionhandling.AbstractParameterizable
          de.lmu.ifi.dbs.elki.math.linearalgebra.pca.SignificantEigenPairFilter

All Implemented Interfaces:

EigenPairFilter, Parameterizable

public class SignificantEigenPairFilter
extends AbstractParameterizable
implements EigenPairFilter

The SignificantEigenPairFilter sorts the eigenpairs in descending order of their eigenvalues and chooses the contrast of an Eigenvalue to the remaining Eigenvalues is maximal. It is closely related to the WeakEigenPairFilter and RelativeEigenPairFilter. But while the RelativeEigenPairFilter chooses the highest dimensionality that satisfies the relative alpha levels, the SignificantEigenPairFilter will chose the local dimensionality such that the 'contrast' is maximal. There are some situations where one or the other is superior, especially when it comes to handling nested clusters and strong global correlations that are not too interesting. These benefits usually only make a difference at higher dimensionalities.

Author:

Erich Schubert

Field Summary

static double	DEFAULT_WALPHA The default value for walpha.
private double	walpha The noise tolerance level for weak eigenvectors
private DoubleParameter	WALPHA_PARAM Parameter weak alpha.

Fields inherited from class de.lmu.ifi.dbs.elki.utilities.optionhandling.AbstractParameterizable

optionHandler

Fields inherited from class de.lmu.ifi.dbs.elki.logging.AbstractLoggable

debug, logger

Constructor Summary

SignificantEigenPairFilter()
Provides a new EigenPairFilter that sorts the eigenpairs in decending order of their eigenvalues and marks the first eigenpairs, whose sum of eigenvalues is higher than the given percentage of the sum of all eigenvalues as string eigenpairs.

Method Summary

FilteredEigenPairs	filter(SortedEigenPairs eigenPairs) Filter eigenpairs
List<String>	setParameters(List<String> args) Set parameters
String	shortDescription() Get parameter description

Methods inherited from class de.lmu.ifi.dbs.elki.utilities.optionhandling.AbstractParameterizable

addOption, addParameterizable, addParameterizable, checkGlobalParameterConstraints, collectOptions, getAttributeSettings, getParameters, rememberParametersExcept, removeOption, removeParameterizable

Methods inherited from class de.lmu.ifi.dbs.elki.logging.AbstractLoggable

debugFine, debugFiner, debugFinest, exception, progress, verbose, warning

Methods inherited from class java.lang.Object

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

Methods inherited from interface de.lmu.ifi.dbs.elki.utilities.optionhandling.Parameterizable

checkGlobalParameterConstraints, collectOptions, getParameters

Field Detail

DEFAULT_WALPHA

public static final double DEFAULT_WALPHA

The default value for walpha. Not used by default, we're going for maximum contrast only.

See Also:

Constant Field Values

WALPHA_PARAM

private final DoubleParameter WALPHA_PARAM

Parameter weak alpha.

walpha

private double walpha

The noise tolerance level for weak eigenvectors

Constructor Detail

SignificantEigenPairFilter

public SignificantEigenPairFilter()

Provides a new EigenPairFilter that sorts the eigenpairs in decending order of their eigenvalues and marks the first eigenpairs, whose sum of eigenvalues is higher than the given percentage of the sum of all eigenvalues as string eigenpairs.

Method Detail

filter

public FilteredEigenPairs filter(SortedEigenPairs eigenPairs)

Filter eigenpairs

Specified by:

filter in interface EigenPairFilter

Parameters:

eigenPairs - the eigenPairs (i.e. the eigenvectors and

Returns:

the filtered eigenpairs

shortDescription

public String shortDescription()

Get parameter description

Specified by:

shortDescription in interface Parameterizable

Overrides:

shortDescription in class AbstractParameterizable

Returns:

Description of the class

setParameters

public List<String> setParameters(List<String> args)
                           throws ParameterException

Set parameters

Specified by:

setParameters in interface Parameterizable

Overrides:

setParameters in class AbstractParameterizable

Parameters:

args - parameters to set the attributes accordingly to

Returns:

a list containing the unused parameters

Throws:

ParameterException - in case of wrong parameter-setting