org.biojavax.ga.functions
Class TournamentSelection

java.lang.Object
  org.biojavax.ga.functions.TournamentSelection

All Implemented Interfaces:

SelectionFunction

public class TournamentSelection
extends Object
implements SelectionFunction

Tournament Selection chooses the best organisms from n random subsets of a given population. Currently it assumes a maximization problem. Perhaps this could be selected depending on the Genetic Algorithm utilized.

Author:

Susanne Merz

Nested Class Summary

Nested classes/interfaces inherited from interface org.biojavax.ga.functions.SelectionFunction

SelectionFunction.SelectAll, SelectionFunction.Threshold

Field Summary

Fields inherited from interface org.biojavax.ga.functions.SelectionFunction

DEFAULT

Constructor Summary

TournamentSelection()
Default constructor: sets the selection pressure to the value of 10.

Method Summary

Population	select(Population pop, GeneticAlgorithm genAlg) Standard call to select organisms, will select a number of Organisms corresponding to 75 % of the population.
Population	selectNIndividuals(Population pop, GeneticAlgorithm ga, int n) This method selects n Organism from the population it is given, using the tournament selection method
void	setSelectionPressure(int numberOfIndividuals) sets the parameter controlling selection pressure

Methods inherited from class java.lang.Object

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

Constructor Detail

TournamentSelection

public TournamentSelection()

Default constructor: sets the selection pressure to the value of 10.

Method Detail

setSelectionPressure

public void setSelectionPressure(int numberOfIndividuals)

sets the parameter controlling selection pressure

Parameters:

numberOfIndividuals - the number of Individuals the best is selected from, ranges from 1 (random selection) to the size of the population (elitism)

select

public Population select(Population pop,
                         GeneticAlgorithm genAlg)
                  throws ChangeVetoException

Standard call to select organisms, will select a number of Organisms corresponding to 75 % of the population.

Specified by:

select in interface SelectionFunction

Parameters:

pop - the Population to select from.

genAlg - the parent GeneticAlgorithm.

Returns:

the Organisms selected

Throws:

ChangeVetoException - if the function attempts to change the population and it is vetoed.

See Also:

SelectionFunction.select(org.biojavax.ga.Population, org.biojavax.ga.GeneticAlgorithm)

selectNIndividuals

public Population selectNIndividuals(Population pop,
                                     GeneticAlgorithm ga,
                                     int n)

This method selects n Organism from the population it is given, using the tournament selection method

Parameters:

pop - the population to select from

ga - the GeneticAlgorithm this selection belongs to

n - number of individuals to be selected.

Returns:

nextgen a Population containing the selected Organisms