jcgp.backend.population

Class Population

java.lang.Object

jcgp.backend.population.Population

public class Population
extends java.lang.Object

This class primarily holds a collection of chromosomes. In addition, it provides a few utility methods for manipulating and copying chromosomes, useful for evolutionary strategies.

copyChromosome() is used to create copies of chromosomes, though it is also possible to create a new instance of population directly from a seed chromosome using the right constructor.

For convenience, a random chromosome can be retrieved using getRandomChromosome(), which is guaranteed to use the experiment's specified seed. If an entirely random population is needed, reinitialise() should be used to randomise all chromosomes without creating a new instance of Population.

Author:

Eduardo Pedroni

Constructor Summary

Constructors

Constructor and Description
Population(Chromosome parent, Resources resources) Initialise a population of copies of the given chromosome.
Population(Resources resources) Initialise a random population according to the parameters specified in the resources.

Method Summary

Modifier and Type	Method and Description
void	copyChromosome(int source, int target) Copy a chromosome into a different position.
Chromosome	get(int index) Returns the indexed chromosome.
Chromosome	getRandomChromosome()
void	reinitialise() Loop through all chromosomes and randomise all connections and functions.
void	sort() Sorts the population in ascending order of fitness quality.

Methods inherited from class java.lang.Object

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

Constructor Detail

Population

public Population(Resources resources)

Initialise a random population according to the parameters specified in the resources.

Parameters:

resources - the experiment's resources.

Population

public Population(Chromosome parent,
                  Resources resources)

Initialise a population of copies of the given chromosome.

Parameters:

parent - the chromosome to use as a model.

resources - a reference to the experiment's resources.

Method Detail

get

public Chromosome get(int index)

Returns the indexed chromosome.

Parameters:

index - the chromosome to return.

Returns:

the indexed chromosome.

getRandomChromosome

public Chromosome getRandomChromosome()

Returns:

a random chromosome from this population.

copyChromosome

public void copyChromosome(int source,
                           int target)

Copy a chromosome into a different position. After this returns, the target chromosome has identical connections and functions to the source one, though they are separate instances. This method does nothing if source == target.

Parameters:

source - the chromosome to copy from.

target - the chromosome to copy to.

reinitialise

public void reinitialise()

Loop through all chromosomes and randomise all connections and functions.

sort

public void sort()

Sorts the population in ascending order of fitness quality. What this means is that the best fitness chromosome will be in the last position, even though it might have the lowest fitness value. Fitness orientation as specified in the resources is respected.