org.simmetrics

Interface MultisetMetric<T>

Type Parameters:

T - the type of elements contained in the sets

All Superinterfaces:

Metric<com.google.common.collect.Multiset<T>>

All Known Implementing Classes:

BlockDistance, CosineSimilarity, EuclideanDistance, GeneralizedJaccard, GeneralizedOverlapCoefficient, SimonWhite

public interface MultisetMetric<T>
extends Metric<com.google.common.collect.Multiset<T>>

Measures the similarity between two arbitrary multisets containing elements of the same type. The measurement results in a value between 0 and 1 inclusive. A value of zero indicates that the sets are dissimilar, a value of 1 indicates they are similar.

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

The elements in the multisets 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 may not modify the contents of the multisets. Multisets should be treated as if wrapped by Multisets.unmodifiableMultiset(Multiset).

Method Summary

Modifier and Type	Method and Description
float	compare(com.google.common.collect.Multiset<T> a, com.google.common.collect.Multiset<T> b) Measures the similarity between multisets a and b.

Method Detail

compare

float compare(com.google.common.collect.Multiset<T> a,
              com.google.common.collect.Multiset<T> b)

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

Results are undefined if a and b are based on different equivalence relations (as HashMultiset and TreeMultiset are).

Specified by:

compare in interface Metric<com.google.common.collect.Multiset<T>>

Parameters:

a - multisets a to compare

b - multisets b to compare

Returns:

a value between 0 and 1 inclusive indicating similarity

Throws:

NullPointerException - when either a or b is null