org.jgap.impl
Class WeightedRouletteSelector

java.lang.Object
  org.jgap.NaturalSelector
      org.jgap.impl.WeightedRouletteSelector

All Implemented Interfaces:

java.io.Serializable, Configurable, INaturalSelector

public class WeightedRouletteSelector
extends NaturalSelector

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.FitnessValueComparator

Constructor Summary

WeightedRouletteSelector()
Default constructor.

WeightedRouletteSelector(Configuration a_config)

Method Summary

protected void	add(IChromosome a_chromosomeToAdd) Add a Chromosome instance to this selector's working pool of Chromosomes.
void	empty() Empty out the working pool of Chromosomes.
boolean	getDoubletteChromosomesAllowed()
boolean	returnsUniqueChromosomes()
void	select(int a_howManyToSelect, Population a_from_pop, 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) Determines whether doublette chromosomes may be added to the selector or will be ignored.

Methods inherited from class org.jgap.NaturalSelector

getConfiguration

Methods inherited from class java.lang.Object

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

Constructor Detail

WeightedRouletteSelector

public WeightedRouletteSelector()

Default constructor.

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

Since:

2.0

WeightedRouletteSelector

public WeightedRouletteSelector(Configuration a_config)

Parameters:

a_config - the configuration to use

Since:

3.0

Method Detail

add

protected void add(IChromosome a_chromosomeToAdd)

Add a Chromosome instance to this selector's working pool of Chromosomes.

Specified by:

add in class NaturalSelector

Parameters:

a_chromosomeToAdd - the chromosom to add to the pool

Since:

1.0

select

public void select(int a_howManyToSelect,
                   Population a_from_pop,
                   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_from_pop - the population the Chromosomes will be selected from

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.

Since:

1.0

returnsUniqueChromosomes

public boolean returnsUniqueChromosomes()

Returns:

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

Since:

2.0

setDoubletteChromosomesAllowed

public void setDoubletteChromosomesAllowed(boolean a_doublettesAllowed)

Determines whether doublette chromosomes may be added to the selector or will be ignored.

Parameters:

a_doublettesAllowed - true: doublette chromosomes allowed to be added to the selector. FALSE: doublettes will be ignored and not added

Since:

2.0

getDoubletteChromosomesAllowed

public boolean getDoubletteChromosomesAllowed()

Returns:

TRUE: doublette chromosomes allowed to be added to the selector

Since:

2.0