io.jenetics.ext.moea

Interface ElementComparator<V>

Type Parameters:

V - the vector type

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@FunctionalInterface
public interface ElementComparator<V>

Defines the order of two elements of a given vector type V. The following example creates an ElementComparator function for a double[] array:

final ElementComparator<double[]> comp = (u, v, i) -> Double.compare(u[i], v[i]);

Since:

4.1

Version:

4.1

Author:

Franz Wilhelmstötter

Method Summary

Modifier and Type	Method and Description
int	compare(V u, V v, int index) Compares the components of a and b at the given index.
default <T> ElementComparator<T>	map(Function<? super T,? extends V> mapper) Return an element comparator for the mapped type T.
default Comparator<V>	ofIndex(int index) Return a comparator which takes the component at the give index for comparison two objects of type T.
default ElementComparator<V>	reversed() Returns a comparator that imposes the reverse ordering of this comparator.

Method Detail

compare

int compare(V u,
            V v,
            int index)

Compares the components of a and b at the given index. E.g.

final ElementComparator<double[]> comp = (u, v, i) -> Double.compare(u[i], v[i]);

Parameters:

u - the first vector

v - the second vector

index - the vector index

Returns:

a negative integer, zero, or a positive integer as the first argument is less than, equal to, or greater than the second.

Throws:

NullPointerException - if either a or b is null

IndexOutOfBoundsException - if the index is out of range (index < 0 || index >= length(a) || index >= length(b))

reversed

default ElementComparator<V> reversed()

Returns a comparator that imposes the reverse ordering of this comparator.

Returns:

a comparator that imposes the reverse ordering of this comparator.

map

default <T> ElementComparator<T> map(Function<? super T,? extends V> mapper)

Return an element comparator for the mapped type T.

Type Parameters:

T - the new comparator type

Parameters:

mapper - the mapper function

Returns:

an element comparator for the mapped type T

ofIndex

default Comparator<V> ofIndex(int index)

Return a comparator which takes the component at the give index for comparison two objects of type T.

Parameters:

index - the component index

Returns:

the component comparator for the given index