com.aliasi.matrix
Class EuclideanDistance

java.lang.Object
  com.aliasi.matrix.EuclideanDistance

All Implemented Interfaces:

Distance<Vector>, Serializable

public class EuclideanDistance
extends Object
implements Distance<Vector>, Serializable

The EuclideanDistance class implements standard Euclidean distance between vectors. Euclidean distance forms a metric. Euclidean distance is often called the L2 distance, because it is 2-norm Minkowski distance.

The definition of Euclidean distance over vectors v1 and v2 is:

 distance(v1,v2) = sqrt(Σi (v1[i] - v2[i])2  )
 

with v1[i] standing for the method call v1.value(i) and i ranging over the dimensions of the vectors, which must be the same.

Note that the Euclidean distance is equivalent to the Minkowski distance metric of order 2. See the class documentation for MinkowskiDistance for more information.

An understandable explanation of Euclidean and related distances may be found at:

• Wikipedia: Distance in Euclidean Space

Since:

LingPipe3.1

Version:

3.1

Author:

Bob Carpenter

See Also:

Serialized Form

Field Summary

static EuclideanDistance

DISTANCE The Euclidean distance.

Constructor Summary

EuclideanDistance()
Construct a new Euclidean distance.

Method Summary

double

distance(Vector v1, Vector v2) Returns the Euclidean distance between the specified pair of vectors.

Methods inherited from class java.lang.Object

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

Field Detail

DISTANCE

public static final EuclideanDistance DISTANCE

The Euclidean distance. All instances of Euclidean distance perform the same function. Because the distance function is thread safe, this instance may be used wherever Euclidean distance is needed.

Constructor Detail

EuclideanDistance

public EuclideanDistance()

Construct a new Euclidean distance.

Method Detail

distance

public double distance(Vector v1,
                       Vector v2)

Returns the Euclidean distance between the specified pair of vectors.

Specified by:

distance in interface Distance<Vector>

Parameters:

v1 - First vector.

v2 - Second vector.

Returns:

The distance between the vectors.

Throws:

IllegalArgumentException - If the vectors are not of the same dimensionality.