Environment for
Supported by Index-Structures

Class SignificantEigenPairFilter

  extended by de.lmu.ifi.dbs.elki.logging.AbstractLoggable
      extended by de.lmu.ifi.dbs.elki.math.linearalgebra.pca.SignificantEigenPairFilter
All Implemented Interfaces:
EigenPairFilter, Parameterizable

@Title(value="Significant EigenPair Filter")
@Description(value="Sorts the eigenpairs in decending order of their eigenvalues and looks for the maxmimum contrast of current Eigenvalue / average of remaining Eigenvalues.")
public class SignificantEigenPairFilter
extends AbstractLoggable
implements EigenPairFilter, Parameterizable

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.

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.logging.AbstractLoggable
debug, logger
Constructor Summary
SignificantEigenPairFilter(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


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


private final DoubleParameter WALPHA_PARAM
Parameter weak alpha.


private double walpha
The noise tolerance level for weak eigenvectors

Constructor Detail


public SignificantEigenPairFilter(Parameterization config)
Constructor, adhering to Parameterizable

config - Parameterization
Method Detail


public FilteredEigenPairs filter(SortedEigenPairs eigenPairs)
Filter eigenpairs

Specified by:
filter in interface EigenPairFilter
eigenPairs - the eigenPairs (i.e. the eigenvectors and
the filtered eigenpairs

Release 0.3 (2010-03-31_1612)