Package elki.distance.minkowski

Class SquaredEuclideanDistance

java.lang.Object

elki.distance.AbstractNumberVectorDistance

elki.distance.minkowski.SquaredEuclideanDistance

All Implemented Interfaces:

Distance<NumberVector>, Norm<NumberVector>, NumberVectorDistance<NumberVector>, PrimitiveDistance<NumberVector>, SpatialPrimitiveDistance<NumberVector>

@Alias("squaredeuclidean")
public class SquaredEuclideanDistance
extends AbstractNumberVectorDistance
implements SpatialPrimitiveDistance<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	Description
static class	SquaredEuclideanDistance.Par	Parameterization class.

Field Summary

Fields

Modifier and Type	Field	Description
static SquaredEuclideanDistance	STATIC	Static instance.

Constructor Summary

Constructors

Constructor	Description
SquaredEuclideanDistance()	Deprecated. Use static instance!

Method Summary

Modifier and Type	Method	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 elki.distance.AbstractNumberVectorDistance

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 elki.distance.Distance

isMetric, isSymmetric

Methods inherited from interface elki.distance.SpatialPrimitiveDistance

instantiate

Field Detail

STATIC

public static final SquaredEuclideanDistance STATIC

Static instance. Use this!

Constructor Detail

SquaredEuclideanDistance

@Deprecated
public SquaredEuclideanDistance()

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: PrimitiveDistance

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

Specified by:

distance in interface NumberVectorDistance<NumberVector>

Specified by:

distance in interface PrimitiveDistance<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: SpatialPrimitiveDistance

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

Specified by:

minDist in interface SpatialPrimitiveDistance<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: Distance

Squared distances, that would become metric after square root.

E.g. squared Euclidean.

Specified by:

isSquared in interface Distance<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: Distance

Get the input data type of the function.

Specified by:

getInputTypeRestriction in interface Distance<NumberVector>

Specified by:

getInputTypeRestriction in interface PrimitiveDistance<NumberVector>

Overrides:

getInputTypeRestriction in class AbstractNumberVectorDistance

Returns:

Type restriction