org.simmetrics

Interface ListMetric<T>

Type Parameters:

T - the type of elements contained in the lists

All Superinterfaces:

Metric<List<T>>

All Known Implementing Classes:

BlockDistance, EuclideanDistance, MatchingCoefficient, MongeElkan, SimonWhite

public interface ListMetric<T>
extends Metric<List<T>>

Measures the similarity between two arbitrary lists containing elements of the same type. 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.

The elements in the lists have to implement Object.hashCode() and Object.equals(Object).

The elements in the lists may not be null if metric does not support null values.

The similarity measure should be consistent with equals such that a.equals(b) => compare(a,b) == 1.0.

The similarity measure should be reflexive such that compare(a,a) == 1.0.

The similarity measure should be symmetric such that compare(a,b) == compare(b,a).

Implementations my not modify the contents of the list. List should be treated as if wrapped by Collections.unmodifiableList(List).

Method Summary

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

Method Detail

compare

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

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 Metric<List<T>>

Parameters:

a - list a to compare

b - list b to compare

Returns:

a value between 0 and 1 inclusive indicating similarity

Throws:

NullPointerException - when either a or b is null

IllegalArgumentException - when either a or b contains null elements and this metric does not permit lists containing null.