org.apache.commons.math3.genetics
Class TournamentSelection

java.lang.Object
  org.apache.commons.math3.genetics.TournamentSelection

All Implemented Interfaces:

SelectionPolicy

public class TournamentSelection
extends Object
implements SelectionPolicy

Tournament selection scheme. Each of the two selected chromosomes is selected based on n-ary tournament -- this is done by drawing arity random chromosomes without replacement from the population, and then selecting the fittest chromosome among them.

Since:

2.0

Version:

$Id: TournamentSelection.java 7721 2013-02-14 14:07:13Z CardosoP $

Constructor Summary

TournamentSelection(int arity)
Creates a new TournamentSelection instance.

Method Summary

int	getArity() Gets the arity (number of chromosomes drawn to the tournament).
ChromosomePair	select(Population population) Select two chromosomes from the population.
void	setArity(int arity) Sets the arity (number of chromosomes drawn to the tournament).

Methods inherited from class java.lang.Object

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

Constructor Detail

TournamentSelection

public TournamentSelection(int arity)

Creates a new TournamentSelection instance.

Parameters:

arity - how many chromosomes will be drawn to the tournament

Method Detail

select

public ChromosomePair select(Population population)
                      throws MathIllegalArgumentException

Select two chromosomes from the population. Each of the two selected chromosomes is selected based on n-ary tournament -- this is done by drawing arity random chromosomes without replacement from the population, and then selecting the fittest chromosome among them.

Specified by:

select in interface SelectionPolicy

Parameters:

population - the population from which the chromosomes are chosen.

Returns:

the selected chromosomes.

Throws:

MathIllegalArgumentException - if the tournament arity is bigger than the population size

getArity

public int getArity()

Gets the arity (number of chromosomes drawn to the tournament).

Returns:

arity of the tournament

setArity

public void setArity(int arity)

Sets the arity (number of chromosomes drawn to the tournament).

Parameters:

arity - arity of the tournament