Module io.jenetics.ext

Package io.jenetics.ext.moea

Class NSGA2Selector<G extends Gene<?,G>,C extends Comparable<? super C>>

java.lang.Object

io.jenetics.ext.moea.NSGA2Selector<G,C>

All Implemented Interfaces:

Selector<G,C>

public class NSGA2Selector<G extends Gene<?,G>,C extends Comparable<? super C>>
extends Object
implements Selector<G,C>

This selector selects the first count elements of the population, which has been sorted by the Crowded-Comparison Operator, as described in A Fast and Elitist Multiobjective Genetic Algorithm: NSGA-II

Reference: K. Deb, A. Pratap, S. Agarwal, and T. Meyarivan. 2002. A fast and elitist multiobjective genetic algorithm: NSGA-II. Trans. Evol. Comp 6, 2 (April 2002), 182-197. DOI= 10.1109/4235.996017

Since:

4.1

Version:

4.1

Constructor Summary

Constructors

Constructor	Description
NSGA2Selector(Comparator<? super C> dominance, ElementComparator<? super C> comparator, ElementDistance<? super C> distance, ToIntFunction<? super C> dimension)	Creates a new NSGA2Selector with the functions needed for handling the multi-objective result type C.

Method Summary

Modifier and Type	Method	Description
static <G extends Gene<?, G>, T, V extends Vec<T>> NSGA2Selector<G,V>	ofVec()	Return a new selector for the given result type V.
ISeq<Phenotype<G,C>>	select(Seq<Phenotype<G,C>> population, int count, Optimize opt)

Methods inherited from class java.lang.Object

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

Constructor Details

NSGA2Selector

public NSGA2Selector(Comparator<? super C> dominance,
 ElementComparator<? super C> comparator,
 ElementDistance<? super C> distance,
 ToIntFunction<? super C> dimension)

Creates a new NSGA2Selector with the functions needed for handling the multi-objective result type C. For the Vec classes, a selector is created like in the following example:

new NSGA2Selector<>(
    Vec<T>::dominance,
    Vec<T>::compare,
    Vec<T>::distance,
    Vec<T>::length
);

Parameters:

dominance - the pareto dominance comparator

comparator - the vector element comparator

distance - the vector element distance

dimension - the dimensionality of vector type C

See Also:

• ofVec()

Method Details

select

public ISeq<Phenotype<G,C>> select(Seq<Phenotype<G,C>> population,
 int count,
 Optimize opt)

Specified by:

select in interface Selector<G extends Gene<?,G>,C extends Comparable<? super C>>

ofVec

public static <G extends Gene<?,
G>,
T,
V extends Vec<T>>
NSGA2Selector<G,V> ofVec()

Return a new selector for the given result type V. This method is a shortcut for

new NSGA2Selector<>(
    Vec<T>::dominance,
    Vec<T>::compare,
    Vec<T>::distance,
    Vec<T>::length
);

Type Parameters:

G - the gene type

T - the array type, e.g. double[]

V - the multi object result type vector

Returns:

a new selector for the given result type V