org.jenetics

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

java.lang.Object

org.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:

2.0 — $Date: 2014-12-28 $

Author:

Franz Wilhelmstötter

See Also:

Tournament selection

Constructor Summary

Constructors

Constructor and Description
TournamentSelector() Create a tournament selector with sample size two.
TournamentSelector(int sampleSize) Create a tournament selector with the give sample size.

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object obj)
int	hashCode()
Population<G,C>	select(Population<G,C> population, int count, Optimize opt) Select phenotypes from the Population.
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

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 Detail

select

public Population<G,C> select(Population<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).

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

toString

public String toString()

Overrides:

toString in class Object