org.apache.mahout.common.distance

Class EuclideanDistanceMeasure

java.lang.Object

org.apache.mahout.common.distance.SquaredEuclideanDistanceMeasure

org.apache.mahout.common.distance.EuclideanDistanceMeasure

All Implemented Interfaces:

DistanceMeasure, Parametered

public class EuclideanDistanceMeasure
extends SquaredEuclideanDistanceMeasure

This class implements a Euclidean distance metric by summing the square root of the squared differences between each coordinate.

If you don't care about the true distance and only need the values for comparison, then the base class, SquaredEuclideanDistanceMeasure, will be faster since it doesn't do the actual square root of the squared differences.

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.mahout.common.parameters.Parametered

Parametered.ParameteredGeneralizations

Field Summary

Fields inherited from interface org.apache.mahout.common.parameters.Parametered

log

Constructor Summary

Constructors

Constructor and Description
EuclideanDistanceMeasure()

Method Summary

Modifier and Type	Method and Description
double	distance(double centroidLengthSquare, Vector centroid, Vector v) Optimized version of distance metric for sparse vectors.
double	distance(Vector v1, Vector v2) Returns the distance metric applied to the arguments

Methods inherited from class org.apache.mahout.common.distance.SquaredEuclideanDistanceMeasure

configure, createParameters, getParameters

Methods inherited from class java.lang.Object

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

Constructor Detail

EuclideanDistanceMeasure

public EuclideanDistanceMeasure()

Method Detail

distance

public double distance(Vector v1,
                       Vector v2)

Description copied from interface: DistanceMeasure

Returns the distance metric applied to the arguments

Specified by:

distance in interface DistanceMeasure

Overrides:

distance in class SquaredEuclideanDistanceMeasure

Parameters:

v1 - a Vector defining a multidimensional point in some feature space

v2 - a Vector defining a multidimensional point in some feature space

Returns:

a scalar doubles of the distance

distance

public double distance(double centroidLengthSquare,
                       Vector centroid,
                       Vector v)

Description copied from interface: DistanceMeasure

Optimized version of distance metric for sparse vectors. This distance computation requires operations proportional to the number of non-zero elements in the vector instead of the cardinality of the vector.

Specified by:

distance in interface DistanceMeasure

Overrides:

distance in class SquaredEuclideanDistanceMeasure

Parameters:

centroidLengthSquare - Square of the length of centroid

centroid - Centroid vector