de.lmu.ifi.dbs.elki.math.linearalgebra.pca.filter

Class RelativeEigenPairFilter

java.lang.Object

de.lmu.ifi.dbs.elki.math.linearalgebra.pca.filter.RelativeEigenPairFilter

All Implemented Interfaces:

EigenPairFilter

@Title(value="Relative EigenPair Filter")
 @Description(value="Sorts the eigenpairs in decending order of their eigenvalues and returns those eigenpairs, whose eigenvalue is above the average (\'expected\') eigenvalue of the remaining eigenvectors.")
public class RelativeEigenPairFilter
extends java.lang.Object
implements EigenPairFilter

The RelativeEigenPairFilter sorts the eigenpairs in descending order of their eigenvalues and marks the first eigenpairs who are a certain factor above the average of the remaining eigenvalues. It is closely related to the WeakEigenPairFilter, and differs mostly by comparing to the remaining Eigenvalues, not to the total sum. 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.

Since:

0.2

Author:

Erich Schubert

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	RelativeEigenPairFilter.Parameterizer Parameterization class.

Field Summary

Fields

Modifier and Type	Field and Description
static double	DEFAULT_RALPHA The default value for ralpha.
private double	ralpha The noise tolerance level for weak eigenvectors

Fields inherited from interface de.lmu.ifi.dbs.elki.math.linearalgebra.pca.filter.EigenPairFilter

PCA_EIGENPAIR_FILTER

Constructor Summary

Constructors

Constructor and Description
RelativeEigenPairFilter(double ralpha) Constructor.

Method Summary

Modifier and Type	Method and Description
int	filter(double[] eigenValues) Filter eigenpairs

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_RALPHA

public static final double DEFAULT_RALPHA

The default value for ralpha.

See Also:

Constant Field Values

ralpha

private double ralpha

The noise tolerance level for weak eigenvectors

Constructor Detail

RelativeEigenPairFilter

public RelativeEigenPairFilter(double ralpha)

Constructor.

Parameters:

ralpha -

Method Detail

filter

public int filter(double[] eigenValues)

Filter eigenpairs

Specified by:

filter in interface EigenPairFilter

Parameters:

eigenValues - the array of eigenvalues, must be sorted descending

Returns:

the number of eigenvectors to keep