ec.simple

Class SimpleBreeder

java.lang.Object

ec.Breeder

ec.simple.SimpleBreeder

All Implemented Interfaces:

Setup, Singleton, java.io.Serializable

Direct Known Subclasses:

NSGA2Breeder, SpatialBreeder, SPEA2Breeder, SteadyStateBreeder

public class SimpleBreeder
extends Breeder

Breeds each subpopulation separately, with no inter-population exchange, and using a generational approach. A SimpleBreeder may have multiple threads; it divvys up a subpopulation into chunks and hands one chunk to each thread to populate. One array of BreedingPipelines is obtained from a population's Species for each operating breeding thread.

Prior to breeding a subpopulation, a SimpleBreeder may first fill part of the new subpopulation up with the best n individuals from the old subpopulation. By default, n is 0 for each subpopulation (that is, this "elitism" is not done). The elitist step is performed by a single thread.

If the sequential parameter below is true, then breeding is done specially: instead of breeding all Subpopulations each generation, we only breed one each generation. The subpopulation index to breed is determined by taking the generation number, modulo the total number of subpopulations. Use of this parameter outside of a coevolutionary context (see ec.coevolve.MultiPopCoevolutionaryEvaluator) is very rare indeed.

SimpleBreeder adheres to the default-subpop parameter in Population: if either an 'elite' or 'reevaluate-elites' parameter is missing, it will use the default subpopulation's value and signal a warning.

Parameters

base.elite.i int >= 0 (default=0)	(the number of elitist individuals for subpopulation i)
base.reevaluate-elites.i boolean (default = false)	(should we reevaluate the elites of subpopulation i each generation?)
base.sequential boolean (default = false)	(should we breed just one subpopulation each generation (as opposed to all of them)?)

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
Population	backupPopulation
boolean	clonePipelineAndPopulation
int[]	elite An array[subpop] of the number of elites to keep for that subpopulation
double[]	eliteFrac
static int	NOT_SET
static java.lang.String	P_CLONE_PIPELINE_AND_POPULATION
static java.lang.String	P_ELITE
static java.lang.String	P_ELITE_FRAC
static java.lang.String	P_REEVALUATE_ELITES
static java.lang.String	P_SEQUENTIAL_BREEDING
ThreadPool	pool
boolean[]	reevaluateElites
boolean	sequentialBreeding

Constructor Summary

Constructors

Constructor and Description
SimpleBreeder()

Method Summary

Modifier and Type	Method and Description
Population	breedPopulation(EvolutionState state) A simple breeder that doesn't attempt to do any cross- population breeding.
int	computeSubpopulationLength(EvolutionState state, Population newpop, int subpopulation, int threadnum) Elites are often stored in the top part of the subpopulation; this function returns what part of the subpopulation contains individuals to replace with newly-bred ones (up to but not including the elites).
int	numElites(EvolutionState state, int subpopulation)
void	setup(EvolutionState state, Parameter base) Sets up the object by reading it from the parameters stored in state, built off of the parameter base base.
boolean	shouldBreedSubpop(EvolutionState state, int subpop, int threadnum) Returns true if we're doing sequential breeding and it's the subpopulation's turn (round robin, one subpopulation per generation).
boolean	usingElitism(int subpopulation)

Methods inherited from class java.lang.Object

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

Field Detail

P_ELITE

public static final java.lang.String P_ELITE

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Constant Field Values

P_ELITE_FRAC

public static final java.lang.String P_ELITE_FRAC

See Also:

Constant Field Values

P_REEVALUATE_ELITES

public static final java.lang.String P_REEVALUATE_ELITES

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Constant Field Values

P_SEQUENTIAL_BREEDING

public static final java.lang.String P_SEQUENTIAL_BREEDING

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Constant Field Values

P_CLONE_PIPELINE_AND_POPULATION

public static final java.lang.String P_CLONE_PIPELINE_AND_POPULATION

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Constant Field Values

elite

public int[] elite

An array[subpop] of the number of elites to keep for that subpopulation

eliteFrac

public double[] eliteFrac

reevaluateElites

public boolean[] reevaluateElites

sequentialBreeding

public boolean sequentialBreeding

clonePipelineAndPopulation

public boolean clonePipelineAndPopulation

backupPopulation

public Population backupPopulation

NOT_SET

public static final int NOT_SET

See Also:

Constant Field Values

pool

public ThreadPool pool

Constructor Detail

SimpleBreeder

public SimpleBreeder()

Method Detail

usingElitism

public boolean usingElitism(int subpopulation)

numElites

public int numElites(EvolutionState state,
                     int subpopulation)

setup

public void setup(EvolutionState state,
                  Parameter base)

Description copied from interface: Setup

Sets up the object by reading it from the parameters stored in state, built off of the parameter base base. If an ancestor implements this method, be sure to call super.setup(state,base); before you do anything else.

computeSubpopulationLength

public int computeSubpopulationLength(EvolutionState state,
                                      Population newpop,
                                      int subpopulation,
                                      int threadnum)

Elites are often stored in the top part of the subpopulation; this function returns what part of the subpopulation contains individuals to replace with newly-bred ones (up to but not including the elites).

breedPopulation

public Population breedPopulation(EvolutionState state)

A simple breeder that doesn't attempt to do any cross- population breeding. Basically it applies pipelines, one per thread, to various subchunks of a new population.

Specified by:

breedPopulation in class Breeder

shouldBreedSubpop

public boolean shouldBreedSubpop(EvolutionState state,
                                 int subpop,
                                 int threadnum)

Returns true if we're doing sequential breeding and it's the subpopulation's turn (round robin, one subpopulation per generation).