org.jgap.impl

Class WeightedRouletteSelector

java.lang.Object

org.jgap.NaturalSelector

org.jgap.NaturalSelectorExt

org.jgap.impl.WeightedRouletteSelector

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable, Configurable, INaturalSelector, ICloneable

public class WeightedRouletteSelector
extends NaturalSelectorExt
implements ICloneable

A basic implementation of NaturalSelector that models a roulette wheel. When a Chromosome is added, it gets a number of "slots" on the wheel equal to its fitness value. When the select method is invoked, the wheel is "spun" and the Chromosome occupying the spot on which it lands is selected. Then the wheel is spun again and again until the requested number of Chromosomes have been selected. Since Chromosomes with higher fitness values get more slots on the wheel, there's a higher statistical probability that they'll be chosen, but it's not guaranteed.

Since:

1.0

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class org.jgap.NaturalSelector

NaturalSelector.AgeFitnessValueComparator, NaturalSelector.FitnessAgeValueComparator, NaturalSelector.FitnessValueComparator

Constructor Summary

Constructors

Constructor and Description
WeightedRouletteSelector() Default constructor.
WeightedRouletteSelector(Configuration a_config)

Method Summary

Modifier and Type	Method and Description
java.lang.Object	clone()
void	empty() Empty out the working pool of Chromosomes.
boolean	equals(java.lang.Object o)
boolean	getDoubletteChromosomesAllowed()
boolean	returnsUniqueChromosomes()
void	selectChromosomes(int a_howManyToSelect, Population a_to_pop) Select a given number of Chromosomes from the pool that will move on to the next generation population.
void	setDoubletteChromosomesAllowed(boolean a_doublettesAllowed) Not supported by this selector! Please do not use it.

Methods inherited from class org.jgap.NaturalSelectorExt

select

Methods inherited from class org.jgap.NaturalSelector

getConfiguration

Methods inherited from class java.lang.Object

getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

WeightedRouletteSelector

public WeightedRouletteSelector()
                         throws InvalidConfigurationException

Default constructor.

Attention: The configuration used is the one set with the static method Genotype.setConfiguration.

Throws:

InvalidConfigurationException

Since:

2.0

WeightedRouletteSelector

public WeightedRouletteSelector(Configuration a_config)
                         throws InvalidConfigurationException

Parameters:

a_config - the configuration to use

Throws:

InvalidConfigurationException

Since:

3.0

Method Detail

selectChromosomes

public void selectChromosomes(int a_howManyToSelect,
                              Population a_to_pop)

Select a given number of Chromosomes from the pool that will move on to the next generation population. This selection should be guided by the fitness values, but fitness should be treated as a statistical probability of survival, not as the sole determining factor. In other words, Chromosomes with higher fitness values should be more likely to be selected than those with lower fitness values, but it should not be guaranteed.

Parameters:

a_howManyToSelect - the number of Chromosomes to select

a_to_pop - the population the Chromosomes will be added to

Since:

1.0

empty

public void empty()

Empty out the working pool of Chromosomes.

Specified by:

empty in interface INaturalSelector

Since:

1.0

returnsUniqueChromosomes

public boolean returnsUniqueChromosomes()

Specified by:

returnsUniqueChromosomes in interface INaturalSelector

Returns:

always false as some Chromosome's could be returnd multiple times

Since:

2.0

setDoubletteChromosomesAllowed

public void setDoubletteChromosomesAllowed(boolean a_doublettesAllowed)

Not supported by this selector! Please do not use it.

Overrides:

setDoubletteChromosomesAllowed in class NaturalSelectorExt

Parameters:

a_doublettesAllowed - do not use

Since:

2.0

getDoubletteChromosomesAllowed

public boolean getDoubletteChromosomesAllowed()

Overrides:

getDoubletteChromosomesAllowed in class NaturalSelectorExt

Returns:

TRUE: doublette chromosomes allowed to be added by the selector

Since:

2.0

clone

public java.lang.Object clone()

Specified by:

clone in interface ICloneable

Overrides:

clone in class java.lang.Object

Returns:

deep clone of this instance

Since:

3.2

equals

public boolean equals(java.lang.Object o)

Overrides:

equals in class NaturalSelectorExt

Parameters:

o - the object to compare

Returns:

true: compared object is seen as equal to current instance