Package org.moeaframework.core.fitness

Class FitnessBasedArchive

java.lang.Object

org.moeaframework.core.Population

org.moeaframework.core.NondominatedPopulation

org.moeaframework.core.fitness.FitnessBasedArchive

All Implemented Interfaces:

Iterable<Solution>, Stateful, Displayable, Formattable<Solution>

public class FitnessBasedArchive
extends NondominatedPopulation

Maintains a non-dominated archive of solutions with a maximum capacity. If the size exceeds the capacity, one or more solutions are pruned based on the fitness calculation. The fitness calculation only occurs when the addition of a solution exceeds the capacity. The fitness can be manually calculated by calling update().

Nested Class Summary

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

NondominatedPopulation.DuplicateMode

Field Summary

Fields

Modifier and Type	Field	Description
protected final int	capacity	The maximum capacity of this archive.
protected final FitnessComparator	fitnessComparator	The fitness comparator for comparing fitness values.
protected final FitnessEvaluator	fitnessEvaluator	The fitness evaluator for computing the fitness of solutions.

Fields inherited from class org.moeaframework.core.NondominatedPopulation

comparator, duplicateMode

Constructor Summary

Constructors

Constructor	Description
FitnessBasedArchive(FitnessEvaluator evaluator, int capacity)	Constructs an empty fitness-based archive.
FitnessBasedArchive(FitnessEvaluator evaluator, int capacity, Iterable<? extends Solution> iterable)	Constructs a fitness-based archive initialized with the specified solutions.
FitnessBasedArchive(FitnessEvaluator evaluator, int capacity, DominanceComparator comparator)	Constructs an empty fitness-based archive.
FitnessBasedArchive(FitnessEvaluator evaluator, int capacity, DominanceComparator comparator, Iterable<? extends Solution> iterable)	Constructs a fitness-based archive initialized with the specified solutions.

Method Summary

Modifier and Type	Method	Description
boolean	add(Solution solution)	If newSolution is dominates any solution or is non-dominated with all solutions in this population, the dominated solutions are removed and newSolution is added to this population.
FitnessBasedArchive	copy()	Returns a copy of this population.
int	getCapacity()	Returns the maximum number of solutions stored in this archive.
void	update()	Updates the fitness of all solutions in this population.

Methods inherited from class org.moeaframework.core.NondominatedPopulation

forceAddWithoutCheck, getComparator, isDuplicate, loadReferenceSet, loadReferenceSet, replace

Methods inherited from class org.moeaframework.core.Population

addAll, addAll, asList, asTabularData, clear, contains, containsAll, containsAll, filter, get, getLowerBounds, getUpperBounds, indexOf, isEmpty, iterator, loadBinary, loadBinary, loadObjectives, loadObjectives, loadState, remove, remove, removeAll, removeAll, removeAll, saveBinary, saveBinary, saveObjectives, saveObjectives, saveState, size, sort, truncate

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.moeaframework.util.format.Displayable

display

Methods inherited from interface org.moeaframework.util.format.Formattable

display, display, display, save, saveCSV

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Field Details

capacity

protected final int capacity

The maximum capacity of this archive.

fitnessEvaluator

protected final FitnessEvaluator fitnessEvaluator

The fitness evaluator for computing the fitness of solutions.

fitnessComparator

protected final FitnessComparator fitnessComparator

The fitness comparator for comparing fitness values.

Constructor Details

FitnessBasedArchive

public FitnessBasedArchive(FitnessEvaluator evaluator,
 int capacity)

Constructs an empty fitness-based archive.

Parameters:

evaluator - the fitness evaluator for computing the fitness of solutions

capacity - the maximum capacity of this archive

FitnessBasedArchive

public FitnessBasedArchive(FitnessEvaluator evaluator,
 int capacity,
 DominanceComparator comparator)

Constructs an empty fitness-based archive.

Parameters:

evaluator - the fitness evaluator for computing the fitness of solutions

capacity - the maximum capacity of this archive

comparator - the dominance comparator

FitnessBasedArchive

public FitnessBasedArchive(FitnessEvaluator evaluator,
 int capacity,
 DominanceComparator comparator,
 Iterable<? extends Solution> iterable)

Constructs a fitness-based archive initialized with the specified solutions.

Parameters:

evaluator - the fitness evaluator for computing the fitness of solutions

capacity - the maximum capacity of this archive

comparator - the dominance comparator

iterable - the solutions used to initialize this population

FitnessBasedArchive

public FitnessBasedArchive(FitnessEvaluator evaluator,
 int capacity,
 Iterable<? extends Solution> iterable)

Constructs a fitness-based archive initialized with the specified solutions.

Parameters:

evaluator - the fitness evaluator for computing the fitness of solutions

capacity - the maximum capacity of this archive

iterable - the solutions used to initialize this population

Method Details

getCapacity

public int getCapacity()

Returns the maximum number of solutions stored in this archive.

Returns:

the maximum number of solutions stored in this archive

add

public boolean add(Solution solution)

Description copied from class: NondominatedPopulation

If newSolution is dominates any solution or is non-dominated with all solutions in this population, the dominated solutions are removed and newSolution is added to this population. Otherwise, newSolution is dominated and is not added to this population.

Overrides:

add in class NondominatedPopulation

Parameters:

solution - the solution to be added

Returns:

true if the population was modified as a result of this method; false otherwise.

update

public void update()

Updates the fitness of all solutions in this population.

copy

public FitnessBasedArchive copy()

Description copied from class: Population

Returns a copy of this population. This can be thought of as a "deep copy", which creates a copy of both the population itself and copies of the individual solutions in the population. Consequently, the returned copy is completely independent, such that any modifications to the contents or order will not impact the original.

Since creating such a "deep copy" can be expensive, prefer using the constructor Population(Iterable) or Population.addAll(Iterable) whenever possible. These alternatives are useful when filtering or reordering the solutions, but the solutions themselves are left unchanged.

Overrides:

copy in class NondominatedPopulation

Returns:

the copy of this population