org.apache.commons.math.genetics

Class Chromosome

java.lang.Object

org.apache.commons.math.genetics.Chromosome

All Implemented Interfaces:

java.lang.Comparable<Chromosome>, Fitness

Direct Known Subclasses:

AbstractListChromosome

public abstract class Chromosome
extends java.lang.Object
implements java.lang.Comparable<Chromosome>, Fitness

Individual in a population. Chromosomes are compared based on their fitness. The chromosomes are IMMUTABLE, and so their fitness is also immutable and therefore it can be cached.

Since:

2.0

Version:

$Revision: 811685 $ $Date: 2009-09-05 19:36:48 +0200 (sam. 05 sept. 2009) $

Field Summary

Fields

Modifier and Type	Field and Description
private double	fitness Cached value of the fitness of this chromosome.

Constructor Summary

Constructors

Constructor and Description
Chromosome()

Method Summary

Modifier and Type	Method and Description
int	compareTo(Chromosome another) Compares two chromosomes based on their fitness.
protected Chromosome	findSameChromosome(Population population) Searches the population for another chromosome with the same representation.
double	getFitness() Access the fitness of this chromosome.
protected boolean	isSame(Chromosome another) Returns true iff another has the same representation and therefore the same fitness.
void	searchForFitnessUpdate(Population population) Searches the population for a chromosome representing the same solution, and if it finds one, updates the fitness to its value.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.commons.math.genetics.Fitness

fitness

Field Detail

fitness

private double fitness

Cached value of the fitness of this chromosome.

Constructor Detail

Chromosome

public Chromosome()

Method Detail

getFitness

public double getFitness()

Access the fitness of this chromosome. The bigger the fitness, the better the chromosome. Computation of fitness is usually very time-consuming task, therefore the fitness is cached.

Returns:

the fitness.

compareTo

public int compareTo(Chromosome another)

Compares two chromosomes based on their fitness. The bigger the fitness, the better the chromosome.

Specified by:

compareTo in interface java.lang.Comparable<Chromosome>

Parameters:

another - another chromosome to compare

Returns:

• -1 if another is better than this
• 1 if another is worse than this
• 0 if the two chromosomes have the same fitness

isSame

protected boolean isSame(Chromosome another)

Returns true iff another has the same representation and therefore the same fitness. By default, it returns false -- override it in your implementation if you need it.

Parameters:

another - chromosome to compare

Returns:

true if another is equivalent to this chromosome

findSameChromosome

protected Chromosome findSameChromosome(Population population)

Searches the population for another chromosome with the same representation. If such chromosome is found, it is returned, if no such chromosome exists, returns null.

Parameters:

population - Population to search

Returns:

Chromosome with the same representation, or null if no such chromosome exists.

searchForFitnessUpdate

public void searchForFitnessUpdate(Population population)

Searches the population for a chromosome representing the same solution, and if it finds one, updates the fitness to its value.

Parameters:

population - Population to search