org.simmetrics

Interface MultisetDistance<E>

Type Parameters:

E - the type of elements contained in the lists

All Superinterfaces:

Distance<com.google.common.collect.Multiset<E>>

All Known Implementing Classes:

BlockDistance, CosineSimilarity, EuclideanDistance, GeneralizedJaccard, SimonWhite

public interface MultisetDistance<E>
extends Distance<com.google.common.collect.Multiset<E>>

Measures the unnormalized dissimilarity 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 lists 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 distance measure should be consistent with equals such that a.equals(b) => distance(a,b) == 0.0.

The distance measure should be reflexive such that distance(a,a) == 0.0.

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

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

See Also:

Wikipedia - Metric

Method Summary

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

Method Detail

distance

float distance(com.google.common.collect.Multiset<E> a,
               com.google.common.collect.Multiset<E> b)

Measures the distance between multisets a and b. The measurement results in a non-negative value. A value of 0.0 indicates that a and b are similar.

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

Specified by:

distance in interface Distance<com.google.common.collect.Multiset<E>>

Parameters:

a - list a to compare

b - list b to compare

Returns:

a non-negative value

Throws:

NullPointerException - when either a or b is null