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

Class PercentageEigenPairFilter

java.lang.Object

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

All Implemented Interfaces:

EigenPairFilter

@Title(value="Percentage based Eigenpair filter")
 @Description(value="Sorts the eigenpairs in decending order of their eigenvalues and returns the first eigenpairs, whose sum of eigenvalues is higher than the given percentage of the sum of all eigenvalues.")
public class PercentageEigenPairFilter
extends java.lang.Object
implements EigenPairFilter

The PercentageEigenPairFilter sorts the eigenpairs in descending 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 strong eigenpairs.

Since:

0.1

Author:

Elke Achtert

Nested Class Summary

Nested Classes

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

Field Summary

Fields

Modifier and Type	Field and Description
private double	alpha The threshold for strong eigenvectors: the strong eigenvectors explain a portion of at least alpha of the total variance.
static double	DEFAULT_ALPHA The default value for alpha.

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

PCA_EIGENPAIR_FILTER

Constructor Summary

Constructors

Constructor and Description
PercentageEigenPairFilter(double alpha) Constructor.

Method Summary

Modifier and Type	Method and Description
int	filter(double[] eigenValues) Filters the specified eigenvalues into strong and weak eigenvalues, where strong eigenvalues have high variance and weak eigenvalues have small variance.

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_ALPHA

public static final double DEFAULT_ALPHA

The default value for alpha.

See Also:

Constant Field Values

alpha

private double alpha

The threshold for strong eigenvectors: the strong eigenvectors explain a portion of at least alpha of the total variance.

Constructor Detail

PercentageEigenPairFilter

public PercentageEigenPairFilter(double alpha)

Constructor.

Parameters:

alpha -

Method Detail

filter

public int filter(double[] eigenValues)

Description copied from interface: EigenPairFilter

Filters the specified eigenvalues into strong and weak eigenvalues, where strong eigenvalues have high variance and weak eigenvalues have small variance.

Specified by:

filter in interface EigenPairFilter

Parameters:

eigenValues - the array of eigenvalues, must be sorted descending

Returns:

the number of eigenvectors to keep