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

Class QuadraticStddevWeight

java.lang.Object

de.lmu.ifi.dbs.elki.math.linearalgebra.pca.weightfunctions.QuadraticStddevWeight

All Implemented Interfaces:

WeightFunction

public final class QuadraticStddevWeight
extends java.lang.Object
implements WeightFunction

Quadratic weight function, scaled using the standard deviation.

We needed another scaling here, we chose the cutoff point to be 3*stddev. If you need another value, you have to reimplement this class.

\( \max\{0.0, 1.0 - \frac{\text{dist}^2}{3\sigma^2} \}\)

Since:

0.2

Author:

Erich Schubert

Field Summary

Fields

Modifier and Type	Field and Description
private static double	scaling Scaling: at scaling * stddev the function will hit 0.0

Constructor Summary

Constructors

Constructor and Description
QuadraticStddevWeight()

Method Summary

Modifier and Type	Method and Description
double	getWeight(double distance, double max, double stddev) Evaluate weight function at given parameters. max is ignored.

Methods inherited from class java.lang.Object

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

Field Detail

scaling

private static final double scaling

Scaling: at scaling * stddev the function will hit 0.0

See Also:

Constant Field Values

Constructor Detail

QuadraticStddevWeight

public QuadraticStddevWeight()

Method Detail

getWeight

public double getWeight(double distance,
                        double max,
                        double stddev)

Evaluate weight function at given parameters. max is ignored.

Specified by:

getWeight in interface WeightFunction

Parameters:

distance - distance of the query point

max - maximum distance of all included points

stddev - standard deviation (i.e. quadratic mean / RMS) of the included points

Returns:

weight for the query point