Module io.jenetics.base

Package io.jenetics

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

java.lang.Object

io.jenetics.TournamentSelector<G,C>

All Implemented Interfaces:

Selector<G,C>

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

In tournament selection the best individual from a random sample of s individuals is chosen from the population P_g. The samples are drawn with replacement. An individual will win a tournament only if its fitness is greater than the fitness of the other s-1 competitors. Note that the worst individual never survives, and the best individual wins in all the tournaments it participates. The selection pressure can be varied by changing the tournament size s . For large values of s, weak individuals have less chance being selected.

Since:

1.0

Version:

6.0

See Also:

• Tournament selection

Constructor Summary

Constructors

Constructor	Description
TournamentSelector()	Create a tournament selector with sample size two.
TournamentSelector(int sampleSize)	Create a tournament selector with the give sample size.
TournamentSelector(Comparator<? super Phenotype<G,C>> comparator, int sampleSize)	Create a tournament selector with the give comparator and sample size.

Method Summary

Modifier and Type	Method	Description
int	sampleSize()	Return the sample size of the tournament selector.
ISeq<Phenotype<G,C>>	select(Seq<Phenotype<G,C>> population, int count, Optimize opt)	Select phenotypes from the Population.
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Details

TournamentSelector

public TournamentSelector(Comparator<? super Phenotype<G,C>> comparator,
 int sampleSize)

Create a tournament selector with the give comparator and sample size. The sample size must be greater than one.

Parameters:

comparator - the comparator use for comparing two individuals during a tournament

sampleSize - the number of individuals involved in one tournament

Throws:

IllegalArgumentException - if the sample size is smaller than two

NullPointerException - if the given comparator is null

Since:

6.0

TournamentSelector

public TournamentSelector(int sampleSize)

Create a tournament selector with the give sample size. The sample size must be greater than one.

Parameters:

sampleSize - the number of individuals involved in one tournament

Throws:

IllegalArgumentException - if the sample size is smaller than two.

TournamentSelector

public TournamentSelector()

Create a tournament selector with sample size two.

Method Details

sampleSize

public int sampleSize()

Return the sample size of the tournament selector.

Returns:

the sample size of the tournament selector

Since:

5.0

select

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

Description copied from interface: Selector

Select phenotypes from the Population.

Specified by:

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

Parameters:

population - The population to select from.

count - The number of phenotypes to select.

opt - Determines whether the individuals with higher fitness values or lower fitness values must be selected. This parameter determines whether the GA maximizes or minimizes the fitness function.

Returns:

The selected phenotypes (a new Population).

toString

public String toString()

Overrides:

toString in class Object