Package org.apache.commons.math.genetics

Class GeneticAlgorithm

java.lang.Object

org.apache.commons.math.genetics.GeneticAlgorithm

public class GeneticAlgorithm
extends java.lang.Object

Implementation of a genetic algorithm. All factors that govern the operation of the algorithm can be configured for a specific problem.

Since:

2.0

Version:

$Revision: 925812 $ $Date: 2010-03-21 16:49:31 +0100 (dim. 21 mars 2010) $

Constructor Summary

Constructors

Constructor	Description
GeneticAlgorithm(CrossoverPolicy crossoverPolicy, double crossoverRate, MutationPolicy mutationPolicy, double mutationRate, SelectionPolicy selectionPolicy)

Method Summary

Modifier and Type	Method	Description
Population	evolve(Population initial, StoppingCondition condition)	Evolve the given population.
CrossoverPolicy	getCrossoverPolicy()	Returns the crossover policy.
double	getCrossoverRate()	Returns the crossover rate.
int	getGenerationsEvolved()	Returns the number of generations evolved to reach StoppingCondition in the last run.
MutationPolicy	getMutationPolicy()	Returns the mutation policy.
double	getMutationRate()	Returns the mutation rate.
static RandomGenerator	getRandomGenerator()	Returns the (static) random generator.
SelectionPolicy	getSelectionPolicy()	Returns the selection policy.
Population	nextGeneration(Population current)	Evolve the given population into the next generation.
static void	setRandomGenerator(RandomGenerator random)	Set the (static) random generator.

Methods inherited from class java.lang.Object

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

Constructor Detail

GeneticAlgorithm

public GeneticAlgorithm(CrossoverPolicy crossoverPolicy,
                        double crossoverRate,
                        MutationPolicy mutationPolicy,
                        double mutationRate,
                        SelectionPolicy selectionPolicy)

Parameters:

crossoverPolicy - The CrossoverPolicy

crossoverRate - The crossover rate as a percentage (0-1 inclusive)

mutationPolicy - The MutationPolicy

mutationRate - The mutation rate as a percentage (0-1 inclusive)

selectionPolicy - The SelectionPolicy

Method Detail

setRandomGenerator

public static void setRandomGenerator(RandomGenerator random)

Set the (static) random generator.

Parameters:

random - random generator

getRandomGenerator

public static RandomGenerator getRandomGenerator()

Returns the (static) random generator.

Returns:

the static random generator shared by GA implementation classes

evolve

public Population evolve(Population initial,
                         StoppingCondition condition)

Evolve the given population. Evolution stops when the stopping condition is satisfied. Updates the generationsEvolved property with the number of generations evolved before the StoppingCondition is satisfied.

Parameters:

initial - the initial, seed population.

condition - the stopping condition used to stop evolution.

Returns:

the population that satisfies the stopping condition.

nextGeneration

public Population nextGeneration(Population current)

Evolve the given population into the next generation.

1. Get nextGeneration population to fill from current generation, using its nextGeneration method
2. Loop until new generation is filled:
• Apply configured SelectionPolicy to select a pair of parents from current
• With probability = getCrossoverRate(), apply configured CrossoverPolicy to parents
• With probability = getMutationRate(), apply configured MutationPolicy to each of the offspring
• Add offspring individually to nextGeneration, space permitting
3. Return nextGeneration

Parameters:

current - the current population.

Returns:

the population for the next generation.

getCrossoverPolicy

public CrossoverPolicy getCrossoverPolicy()

Returns the crossover policy.

Returns:

crossover policy

getCrossoverRate

public double getCrossoverRate()

Returns the crossover rate.

Returns:

crossover rate

getMutationPolicy

public MutationPolicy getMutationPolicy()

Returns the mutation policy.

Returns:

mutation policy

getMutationRate

public double getMutationRate()

Returns the mutation rate.

Returns:

mutation rate

getSelectionPolicy

public SelectionPolicy getSelectionPolicy()

Returns the selection policy.

Returns:

selection policy

getGenerationsEvolved

public int getGenerationsEvolved()

Returns the number of generations evolved to reach StoppingCondition in the last run.

Returns:

number of generations evolved

Since:

2.1