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

java.lang.Object
  de.lmu.ifi.dbs.elki.logging.AbstractLoggable
      de.lmu.ifi.dbs.elki.math.linearalgebra.pca.RelativeEigenPairFilter

All Implemented Interfaces:

EigenPairFilter, Parameterizable

@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 AbstractLoggable
implements EigenPairFilter, Parameterizable

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.

Author:

Erich Schubert

Field Summary

static double	DEFAULT_RALPHA The default value for ralpha.
static OptionID	EIGENPAIR_FILTER_RALPHA OptionID for RALPHA_PARAM
private double	ralpha The noise tolerance level for weak eigenvectors
private DoubleParameter	RALPHA_PARAM Parameter relative alpha.

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

debug, logger

Constructor Summary

RelativeEigenPairFilter(Parameterization config)
Constructor, adhering to Parameterizable

Method Summary

FilteredEigenPairs

filter(SortedEigenPairs eigenPairs) Filter eigenpairs

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

Field Detail

EIGENPAIR_FILTER_RALPHA

public static final OptionID EIGENPAIR_FILTER_RALPHA

OptionID for RALPHA_PARAM

DEFAULT_RALPHA

public static final double DEFAULT_RALPHA

The default value for ralpha.

See Also:

Constant Field Values

RALPHA_PARAM

private final DoubleParameter RALPHA_PARAM

Parameter relative alpha.

ralpha

private double ralpha

The noise tolerance level for weak eigenvectors

Constructor Detail

RelativeEigenPairFilter

public RelativeEigenPairFilter(Parameterization config)

Constructor, adhering to Parameterizable

Parameters:

config - Parameterization

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