de.lmu.ifi.dbs.elki.distance.distancefunction

Class MatrixWeightedQuadraticDistanceFunction

java.lang.Object

de.lmu.ifi.dbs.elki.distance.distancefunction.AbstractNumberVectorDistanceFunction

de.lmu.ifi.dbs.elki.distance.distancefunction.MatrixWeightedQuadraticDistanceFunction

All Implemented Interfaces:

DistanceFunction<NumberVector>, Norm<NumberVector>, NumberVectorDistanceFunction<NumberVector>, PrimitiveDistanceFunction<NumberVector>

Direct Known Subclasses:

HSBHistogramQuadraticDistanceFunction, MahalanobisDistanceFunction, RGBHistogramQuadraticDistanceFunction

public class MatrixWeightedQuadraticDistanceFunction
extends AbstractNumberVectorDistanceFunction
implements Norm<NumberVector>

Matrix weighted quadratic distance, the squared form of MahalanobisDistanceFunction. For a weight matrix M, this distance is defined as \[ \text{Mahalanobis}^2_M(\vec{x},\vec{y}) := (\vec{x}-\vec{y})^T * M * (\vec{x}-\vec{y}) \] TODO: Add a factory with parameterizable weight matrix! Right now, this can only be used from Java and from subclasses, not from command line or MiniGUI.

Since:

0.1

Author:

Elke Achtert

Field Summary

Fields

Modifier and Type	Field and Description
protected double[][]	weightMatrix The weight matrix.

Constructor Summary

Constructors

Constructor and Description
MatrixWeightedQuadraticDistanceFunction(double[][] weightMatrix) Constructor.

Method Summary

Modifier and Type	Method and Description
double	distance(NumberVector o1, NumberVector o2) Computes the distance between two given DatabaseObjects according to this distance function.
boolean	equals(java.lang.Object obj)
VectorFieldTypeInformation<? super NumberVector>	getInputTypeRestriction() Get the input data type of the function.
int	hashCode()
boolean	isSquared() Squared distances, that would become metric after square root.
double	norm(NumberVector obj) Compute the norm of object obj.

Methods inherited from class de.lmu.ifi.dbs.elki.distance.distancefunction.AbstractNumberVectorDistanceFunction

dimensionality, dimensionality, dimensionality, dimensionality, dimensionality, dimensionality, dimensionality, dimensionality

Methods inherited from class java.lang.Object

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

Methods inherited from interface de.lmu.ifi.dbs.elki.distance.distancefunction.PrimitiveDistanceFunction

instantiate

Methods inherited from interface de.lmu.ifi.dbs.elki.distance.distancefunction.DistanceFunction

isMetric, isSymmetric

Field Detail

weightMatrix

protected double[][] weightMatrix

The weight matrix.

Constructor Detail

MatrixWeightedQuadraticDistanceFunction

public MatrixWeightedQuadraticDistanceFunction(double[][] weightMatrix)

Constructor.

Parameters:

weightMatrix - weight matrix

Method Detail

distance

public double distance(NumberVector o1,
                       NumberVector o2)

Description copied from interface: PrimitiveDistanceFunction

Computes the distance between two given DatabaseObjects according to this distance function.

Specified by:

distance in interface NumberVectorDistanceFunction<NumberVector>

Specified by:

distance in interface PrimitiveDistanceFunction<NumberVector>

Parameters:

o1 - first DatabaseObject

o2 - second DatabaseObject

Returns:

the distance between two given DatabaseObjects according to this distance function

isSquared

public boolean isSquared()

Description copied from interface: DistanceFunction

Squared distances, that would become metric after square root. E.g. squared Euclidean.

Specified by:

isSquared in interface DistanceFunction<NumberVector>

Returns:

true when squared.

norm

public double norm(NumberVector obj)

Description copied from interface: Norm

Compute the norm of object obj.

Specified by:

norm in interface Norm<NumberVector>

Parameters:

obj - Object

Returns:

Norm

equals

public boolean equals(java.lang.Object obj)

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

getInputTypeRestriction

public VectorFieldTypeInformation<? super NumberVector> getInputTypeRestriction()

Description copied from interface: DistanceFunction

Get the input data type of the function.

Specified by:

getInputTypeRestriction in interface DistanceFunction<NumberVector>

Specified by:

getInputTypeRestriction in interface PrimitiveDistanceFunction<NumberVector>

Overrides:

getInputTypeRestriction in class AbstractNumberVectorDistanceFunction

Returns:

Type restriction