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

Class SquaredEuclideanDistanceFunction

java.lang.Object

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

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

All Implemented Interfaces:

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

@Alias(value={"squaredeuclidean","de.lmu.ifi.dbs.elki.distance.distancefunction.SquaredEuclideanDistanceFunction"})
public class SquaredEuclideanDistanceFunction
extends AbstractNumberVectorDistanceFunction
implements SpatialPrimitiveDistanceFunction<NumberVector>, Norm<NumberVector>

Squared Euclidean distance, optimized for SparseNumberVectors. This results in the same rankings as regular Euclidean distance, but saves computing the square root.

Squared Euclidean is defined as: \[ \text{Euclidean}^2(\vec{x},\vec{y}) := \sum_i (x_i-y_i)^2 \]

Since:

0.1

Author:

Arthur Zimek

Nested Class Summary

Nested Classes

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

Field Summary

Fields

Modifier and Type	Field and Description
static SquaredEuclideanDistanceFunction	STATIC Static instance.

Constructor Summary

Constructors

Constructor and Description
SquaredEuclideanDistanceFunction() Deprecated. Use static instance!

Method Summary

Modifier and Type	Method and Description
double	distance(double[] v1, double[] v2) Special version for double arrays.
double	distance(NumberVector v1, NumberVector v2) Computes the distance between two given DatabaseObjects according to this distance function.
boolean	equals(java.lang.Object obj)
SimpleTypeInformation<? 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	minDist(SpatialComparable mbr1, SpatialComparable mbr2) Computes the distance between the two given MBRs according to this distance function.
double	norm(NumberVector v) Compute the norm of object obj.
private double	preDistance(double[] v1, double[] v2, int start, int end)
private double	preDistance(NumberVector v1, NumberVector v2, int start, int end)
private double	preDistanceMBR(SpatialComparable mbr1, SpatialComparable mbr2, int start, int end)
private double	preDistanceVM(NumberVector v, SpatialComparable mbr, int start, int end)
private double	preNorm(double[] v, int start, int end)
private double	preNorm(NumberVector v, int start, int end)
private double	preNormMBR(SpatialComparable mbr, int start, int end)
java.lang.String	toString()

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, wait, wait, wait

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

instantiate

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

isMetric, isSymmetric

Field Detail

STATIC

public static final SquaredEuclideanDistanceFunction STATIC

Static instance. Use this!

Constructor Detail

SquaredEuclideanDistanceFunction

@Deprecated
public SquaredEuclideanDistanceFunction()

Deprecated. Use static instance!

Constructor - use STATIC instead.

Method Detail

preDistance

private double preDistance(double[] v1,
                           double[] v2,
                           int start,
                           int end)

preDistance

private double preDistance(NumberVector v1,
                           NumberVector v2,
                           int start,
                           int end)

preDistanceVM

private double preDistanceVM(NumberVector v,
                             SpatialComparable mbr,
                             int start,
                             int end)

preDistanceMBR

private double preDistanceMBR(SpatialComparable mbr1,
                              SpatialComparable mbr2,
                              int start,
                              int end)

preNorm

private double preNorm(NumberVector v,
                       int start,
                       int end)

preNorm

private double preNorm(double[] v,
                       int start,
                       int end)

preNormMBR

private double preNormMBR(SpatialComparable mbr,
                          int start,
                          int end)

distance

public double distance(NumberVector v1,
                       NumberVector v2)

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:

v1 - first DatabaseObject

v2 - second DatabaseObject

Returns:

the distance between two given DatabaseObjects according to this distance function

distance

public double distance(double[] v1,
                       double[] v2)

Special version for double arrays.

norm

public double norm(NumberVector v)

Description copied from interface: Norm

Compute the norm of object obj.

Specified by:

norm in interface Norm<NumberVector>

Parameters:

v - Object

Returns:

Norm

minDist

public double minDist(SpatialComparable mbr1,
                      SpatialComparable mbr2)

Description copied from interface: SpatialPrimitiveDistanceFunction

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

Specified by:

minDist in interface SpatialPrimitiveDistanceFunction<NumberVector>

Parameters:

mbr1 - the first MBR object

mbr2 - the second MBR object

Returns:

the distance between the two given MBRs 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.

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

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 SimpleTypeInformation<? 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