org.simmetrics.metrics

Class SimonWhite<T>

java.lang.Object

org.simmetrics.metrics.SimonWhite<T>

Type Parameters:

T - type of the token

All Implemented Interfaces:

ListMetric<T>, Metric<List<T>>

public class SimonWhite<T>
extends Object
implements ListMetric<T>

Simon White algorithm providing a similarity measure between two lists. Implementation based on the ideas as outlined in How to Strike a Match by Simon White.

similarity(a,b) = 2 * |(a A b)| / (|a| + |b|)

The A operation takes the list intersection of a and b. This is a list c such that each element in has a 1-to-1 relation to an element in both a and b. E.g. the list intersection of [ab,ab,ab,ac] and [ab,ab,ad] is [ab,ab].

This metric is very similar to Dice's coefficient however Simon White used the list intersection rather then the set intersection to prevent list of duplicates from scoring a perfect match against a list with single elements. E.g. 'GGGGG' should not be identical to 'GG'.

This class is immutable and thread-safe.

See Also:

DiceSimilarity

Constructor Summary

Constructors

Constructor and Description
SimonWhite()

Method Summary

Modifier and Type	Method and Description
float	compare(List<T> a, List<T> b) Measures the similarity between lists a and b.
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

SimonWhite

public SimonWhite()

Method Detail

compare

public float compare(List<T> a,
                     List<T> b)

Description copied from interface: ListMetric

Measures the similarity between lists a and b. The measurement results in a value between 0 and 1 inclusive. A value of zero indicates that the lists are dissimilar, a value of 1 indicates they are similar.

Specified by:

compare in interface ListMetric<T>

Specified by:

compare in interface Metric<List<T>>

Parameters:

a - list a to compare

b - list b to compare

Returns:

a value between 0 and 1 inclusive indicating similarity

toString

public String toString()

Overrides:

toString in class Object