Package org.moeaframework.algorithm.continuation

Class EpsilonProgressContinuation

java.lang.Object

org.moeaframework.core.PeriodicAction

org.moeaframework.algorithm.continuation.AdaptiveTimeContinuation

org.moeaframework.algorithm.continuation.EpsilonProgressContinuation

All Implemented Interfaces:

Algorithm, Configurable, EvolutionaryAlgorithm, Stateful

public class EpsilonProgressContinuation
extends AdaptiveTimeContinuation

Extends AdaptiveTimeContinuation to trigger restarts using ε-progress. ε-progress measures search progress by counting the number of significant improvements, as measured by the number of unoccupied ε-boxes filled during a fixed time window.

References:

1. Hadka, D. and Reed, P. "Borg: An Auto-Adaptive Many-Objective Evolutionary Computing Framework." Evolutionary Computation, 21(2):231-259, 2013.

Nested Class Summary

Nested classes/interfaces inherited from class org.moeaframework.core.PeriodicAction

PeriodicAction.FrequencyType

Field Summary

Fields inherited from class org.moeaframework.core.PeriodicAction

algorithm, frequency, frequencyType, iteration, lastInvocation

Constructor Summary

Constructors

Constructor	Description
EpsilonProgressContinuation(EpsilonBoxEvolutionaryAlgorithm algorithm, int windowSize, int maxWindowSize, double injectionRate, int minimumPopulationSize, int maximumPopulationSize, Selection selection, Variation variation)	Decorates the specified algorithm with ε-progress triggered time continuation.

Method Summary

Modifier and Type	Method	Description
protected RestartType	check()	Performs a check to determine if a restart should occur.
EpsilonBoxDominanceArchive	getArchive()	Returns the current non-dominated archive of the best solutions generated by this evolutionary algorithm, or null if no archive is used.
void	loadState(ObjectInputStream stream)	Loads the state of this object from the stream.
protected void	restart(RestartType type)	Performs a restart.
void	saveState(ObjectOutputStream stream)	Writes the state of this object to the stream.

Methods inherited from class org.moeaframework.algorithm.continuation.AdaptiveTimeContinuation

addRestartListener, doAction, getAlgorithm, getInjectionRate, getMaximumPopulationSize, getMaxWindowSize, getMinimumPopulationSize, getPopulation, getWindowSize, removeRestartListener, setInjectionRate, setMaximumPopulationSize, setMaxWindowSize, setMinimumPopulationSize, setWindowSize

Methods inherited from class org.moeaframework.core.PeriodicAction

evaluate, getNumberOfEvaluations, getProblem, getResult, isTerminated, step, terminate

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.moeaframework.core.Algorithm

evaluate, getNumberOfEvaluations, getProblem, getResult, isTerminated, run, run, step, terminate

Methods inherited from interface org.moeaframework.core.configuration.Configurable

applyConfiguration, getConfiguration

Constructor Details

EpsilonProgressContinuation

public EpsilonProgressContinuation(EpsilonBoxEvolutionaryAlgorithm algorithm,
 int windowSize,
 int maxWindowSize,
 double injectionRate,
 int minimumPopulationSize,
 int maximumPopulationSize,
 Selection selection,
 Variation variation)

Decorates the specified algorithm with ε-progress triggered time continuation.

Parameters:

algorithm - the algorithm being decorated

windowSize - the number of iterations between invocations of check

maxWindowSize - the maximum number of iterations allowed since the last restart before forcing a restart

injectionRate - the injection rate

minimumPopulationSize - the minimum size of the population

maximumPopulationSize - the maximum size of the population

selection - the selection operator for selecting solutions from the archive during a restart

variation - the variation operator for mutating solutions selected from the archive during a restart

Method Details

getArchive

public EpsilonBoxDominanceArchive getArchive()

Description copied from interface: EvolutionaryAlgorithm

Returns the current non-dominated archive of the best solutions generated by this evolutionary algorithm, or null if no archive is used.

Specified by:

getArchive in interface EvolutionaryAlgorithm

Overrides:

getArchive in class AdaptiveTimeContinuation

Returns:

the current non-dominated archive of the best solutions generated by this evolutionary algorithm, or null if no archive is used

check

protected RestartType check()

Description copied from class: AdaptiveTimeContinuation

Performs a check to determine if a restart should occur. Returns RestartType.NONE if no restart should occur; or RestartType.HARD if the population-to-archive ratio exceeds populationRatio by more than 25% or the number of fitness evaluations since the last restart exceeds maxWindowSize.

Overrides:

check in class AdaptiveTimeContinuation

Returns:

RestartType.NONE if no restart should occur; or RestartType.HARD if the population-to-archive ratio exceeds populationRatio by more than 25% or if the number of fitness evaluations since the last restart exceeds maxWindowSize

restart

protected void restart(RestartType type)

Description copied from class: AdaptiveTimeContinuation

Performs a restart. If the type is RestartType.HARD, the population is emptied, resized and filled with solutions selected and mutated from the archive. If the type is RestartType.SOFT, the population is not emptied; new solutions are only added to fill any empty slots.

Overrides:

restart in class AdaptiveTimeContinuation

Parameters:

type - the type of restart

saveState

public void saveState(ObjectOutputStream stream)
               throws IOException

Description copied from interface: Stateful

Writes the state of this object to the stream. The order that objects are written to the stream is important. We recommend first calling super.saveState(stream) followed by writing each field.

Specified by:

saveState in interface Stateful

Overrides:

saveState in class AdaptiveTimeContinuation

Parameters:

stream - the stream

Throws:

IOException - if an I/O error occurred

loadState

public void loadState(ObjectInputStream stream)
               throws IOException,
ClassNotFoundException

Description copied from interface: Stateful

Loads the state of this object from the stream. The order for reading objects from the stream must match the order they are written to the stream in Stateful.saveState(ObjectOutputStream).

Specified by:

loadState in interface Stateful

Overrides:

loadState in class AdaptiveTimeContinuation

Parameters:

stream - the stream

Throws:

IOException - if an I/O error occurred

ClassNotFoundException - if the stream referenced a class that is not defined