ec.multiobjective.nsga2

Class NSGA2Breeder

java.lang.Object

ec.Breeder

ec.simple.SimpleBreeder

ec.multiobjective.nsga2.NSGA2Breeder

All Implemented Interfaces:

Setup, Singleton, java.io.Serializable

public class NSGA2Breeder
extends SimpleBreeder

This SimpleBreeder subclass breeds a set of children from the Population, then joins the original Population with the children in a (mu+mu) fashion. An NSGA2Breeder may have multiple threads for breeding.

NSGA-II has fixed archive size (the population size), and so ignores the 'elites' declaration. However it will adhere to the 'reevaluate-elites' parameter in SimpleBreeder to determine whether to force fitness reevaluation.

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	NSGA2Breeder.BreedingState We use a state variable to make sure that the nextSubpopulationSize() method is only called at the appropriate time.

Field Summary

Fields inherited from class ec.simple.SimpleBreeder

backupPopulation, clonePipelineAndPopulation, elite, eliteFrac, newIndividuals, NOT_SET, P_CLONE_PIPELINE_AND_POPULATION, P_ELITE, P_ELITE_FRAC, P_REEVALUATE_ELITES, P_SEQUENTIAL_BREEDING, pool, reevaluateElites, sequentialBreeding

Constructor Summary

Constructors

Constructor and Description
NSGA2Breeder()

Method Summary

Modifier and Type	Method and Description
java.util.ArrayList<java.util.ArrayList<Individual>>	assignFrontRanks(Subpopulation subpop) Divides inds into ranks and assigns each individual's rank to be the rank it was placed into.
Population	breedPopulation(EvolutionState state) Use super's breeding, but also set our local state to record that breeding is complete.
protected void	loadElites(EvolutionState state, Population newpop) A protected helper function for breedPopulation which loads elites into a subpopulation.
int	numElites(EvolutionState state, int subpopulation)
void	postProcess(EvolutionState state) A hook to do final modifications as necessary to the population after breeding has concluded.
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.

Methods inherited from class ec.simple.SimpleBreeder

breedPopChunk, breedPopChunkProduce, nextSubpopulationSize, shouldBreedSubpop, unmarkElitesEvaluated, usingElitism

Methods inherited from class java.lang.Object

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

Constructor Detail

NSGA2Breeder

public NSGA2Breeder()

Method Detail

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.

Specified by:

setup in interface Setup

Overrides:

setup in class SimpleBreeder

numElites

public int numElites(EvolutionState state,
                     int subpopulation)

Overrides:

numElites in class SimpleBreeder

loadElites

protected void loadElites(EvolutionState state,
                          Population newpop)

Description copied from class: SimpleBreeder

A protected helper function for breedPopulation which loads elites into a subpopulation.

Overrides:

loadElites in class SimpleBreeder

postProcess

public void postProcess(EvolutionState state)

Description copied from class: SimpleBreeder

A hook to do final modifications as necessary to the population after breeding has concluded. By default this does nothing, but multiobjective breeders, which temporarily replace the old population while it's being breeded, may use this to put the popuplation back again just in case statistics needs it.

Overrides:

postProcess in class SimpleBreeder

breedPopulation

public Population breedPopulation(EvolutionState state)

Use super's breeding, but also set our local state to record that breeding is complete.

Overrides:

breedPopulation in class SimpleBreeder

assignFrontRanks

public java.util.ArrayList<java.util.ArrayList<Individual>> assignFrontRanks(Subpopulation subpop)

Divides inds into ranks and assigns each individual's rank to be the rank it was placed into. Each front is an ArrayList.