Package net.bmahe.genetics4j.neat.spec.selection

Class ImmutableNeatSelection<T extends Comparable<T>>

java.lang.Object

net.bmahe.genetics4j.neat.spec.selection.NeatSelection<T>

net.bmahe.genetics4j.neat.spec.selection.ImmutableNeatSelection<T>

All Implemented Interfaces:

SelectionPolicy

@Generated("org.immutables.processor.ProxyProcessor")
public final class ImmutableNeatSelection<T extends Comparable<T>>
extends NeatSelection<T>

Immutable implementation of NeatSelection.

Use the builder to create immutable instances: new NeatSelection.Builder().

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	ImmutableNeatSelection.Builder<T extends Comparable<T>>	Builds instances of type ImmutableNeatSelection.
private final class	ImmutableNeatSelection.InitShim

Field Summary

Fields

Modifier and Type	Field	Description
private ImmutableNeatSelection<T>.InitShim	initShim
private final int	minSpeciesSize
private final float	perSpeciesKeepRatio
private final BiPredicate<Individual<T>,Individual<T>>	speciesPredicate
private final SelectionPolicy	speciesSelection
private static final byte	STAGE_INITIALIZED
private static final byte	STAGE_INITIALIZING
private static final byte	STAGE_UNINITIALIZED

Constructor Summary

Constructors

Modifier	Constructor	Description
private	ImmutableNeatSelection(float perSpeciesKeepRatio, int minSpeciesSize, BiPredicate<Individual<T>,Individual<T>> speciesPredicate, SelectionPolicy speciesSelection)
private	ImmutableNeatSelection(ImmutableNeatSelection.Builder<T> builder)

Method Summary

Modifier and Type	Method	Description
static <T extends Comparable<T>> ImmutableNeatSelection<T>	copyOf(NeatSelection<T> instance)	Creates an immutable copy of a NeatSelection value.
boolean	equals(Object another)	This instance is equal to all instances of ImmutableNeatSelection that have equal attribute values.
private boolean	equalTo(int synthetic, ImmutableNeatSelection<?> another)
int	hashCode()	Computes a hash code from attributes: perSpeciesKeepRatio, minSpeciesSize, speciesPredicate, speciesSelection.
int	minSpeciesSize()	Returns the minimum number of individuals required to maintain a species.
float	perSpeciesKeepRatio()	Returns the proportion of each species to preserve for reproduction.
BiPredicate<Individual<T>,Individual<T>>	speciesPredicate()	Returns the predicate used to determine species membership.
SelectionPolicy	speciesSelection()	Returns the selection policy used within each species.
String	toString()	Prints the immutable value NeatSelection with attribute values.
private static <T extends Comparable<T>> ImmutableNeatSelection<T>	validate(ImmutableNeatSelection<T> instance)
final ImmutableNeatSelection<T>	withMinSpeciesSize(int value)	Copy the current immutable object by setting a value for the minSpeciesSize attribute.
final ImmutableNeatSelection<T>	withPerSpeciesKeepRatio(float value)	Copy the current immutable object by setting a value for the perSpeciesKeepRatio attribute.
final ImmutableNeatSelection<T>	withSpeciesPredicate(BiPredicate<Individual<T>,Individual<T>> value)	Copy the current immutable object by setting a value for the speciesPredicate attribute.
final ImmutableNeatSelection<T>	withSpeciesSelection(SelectionPolicy value)	Copy the current immutable object by setting a value for the speciesSelection attribute.

Methods inherited from class net.bmahe.genetics4j.neat.spec.selection.NeatSelection

builder, check, of, of, ofDefault

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Details

perSpeciesKeepRatio

private final float perSpeciesKeepRatio

minSpeciesSize

private final int minSpeciesSize

speciesPredicate

private final BiPredicate<Individual<T extends Comparable<T>>,Individual<T extends Comparable<T>>> speciesPredicate

speciesSelection

private final SelectionPolicy speciesSelection

STAGE_INITIALIZING

private static final byte STAGE_INITIALIZING

See Also:

• Constant Field Values

STAGE_UNINITIALIZED

private static final byte STAGE_UNINITIALIZED

See Also:

• Constant Field Values

STAGE_INITIALIZED

private static final byte STAGE_INITIALIZED

See Also:

• Constant Field Values

initShim

private transient volatile ImmutableNeatSelection<T extends Comparable<T>>.InitShim initShim

Constructor Details

ImmutableNeatSelection

private ImmutableNeatSelection(ImmutableNeatSelection.Builder<T> builder)

ImmutableNeatSelection

private ImmutableNeatSelection(float perSpeciesKeepRatio,
 int minSpeciesSize,
 BiPredicate<Individual<T>,Individual<T>> speciesPredicate,
 SelectionPolicy speciesSelection)

Method Details

perSpeciesKeepRatio

public float perSpeciesKeepRatio()

Returns the proportion of each species to preserve for reproduction.

This ratio determines what fraction of each species will be retained after fitness-based culling. Higher values preserve more diversity within species but may slow convergence, while lower values increase selection pressure but may lose beneficial genetic variations.

Typical values:

• 0.9 (default): Preserve top 90% of each species
• 0.8-0.95: Balanced diversity preservation
• < 0.8: Aggressive selection pressure
• > 0.95: Minimal selection pressure, maximum diversity

Overrides:

perSpeciesKeepRatio in class NeatSelection<T extends Comparable<T>>

Returns:

keep ratio between 0.0 and 1.0 (exclusive of 0.0, inclusive of 1.0)

minSpeciesSize

public int minSpeciesSize()

Returns the minimum number of individuals required to maintain a species.

Species with fewer members than this threshold will be eliminated to prevent resource waste on non-viable populations. This helps focus evolutionary resources on species with sufficient genetic diversity to explore their local fitness landscape effectively.

Typical values:

• 5 (default): Balanced viability threshold
• 3-10: Reasonable range for most problems
• < 3: Very permissive, allows small species to survive
• > 10: Strict threshold, eliminates marginal species

Overrides:

minSpeciesSize in class NeatSelection<T extends Comparable<T>>

Returns:

minimum species size (must be positive)

speciesPredicate

public BiPredicate<Individual<T>,Individual<T>> speciesPredicate()

Returns the predicate used to determine species membership.

This bi-predicate takes two individuals and returns true if they should belong to the same species based on their genetic compatibility. Typically implemented using NEAT compatibility distance with a threshold value.

Common implementations:

• Compatibility distance: Based on matching, disjoint, excess genes and weight differences
• Topological similarity: Based on network structure similarity
• Behavioral similarity: Based on network output patterns
• Custom metrics: Domain-specific similarity measures

Specified by:

speciesPredicate in class NeatSelection<T extends Comparable<T>>

Returns:

bi-predicate for determining species membership

speciesSelection

public SelectionPolicy speciesSelection()

Returns the selection policy used within each species.

After individuals are organized into species, this policy determines how parents are selected within each species for reproduction. Common choices include tournament selection, proportional selection, or rank-based selection.

Selection policy considerations:

• Tournament selection: Good balance of selection pressure and diversity
• Proportional selection: Fitness-proportionate selection within species
• Rank selection: Rank-based selection to avoid fitness scaling issues
• Elite selection: Always select best individuals within species

Specified by:

speciesSelection in class NeatSelection<T extends Comparable<T>>

Returns:

selection policy for within-species parent selection

withPerSpeciesKeepRatio

public final ImmutableNeatSelection<T> withPerSpeciesKeepRatio(float value)

Copy the current immutable object by setting a value for the perSpeciesKeepRatio attribute. A value strict bits equality used to prevent copying of the same value by returning this.

Parameters:

value - A new value for perSpeciesKeepRatio

Returns:

A modified copy of the this object

withMinSpeciesSize

public final ImmutableNeatSelection<T> withMinSpeciesSize(int value)

Copy the current immutable object by setting a value for the minSpeciesSize attribute. A value equality check is used to prevent copying of the same value by returning this.

Parameters:

value - A new value for minSpeciesSize

Returns:

A modified copy of the this object

withSpeciesPredicate

public final ImmutableNeatSelection<T> withSpeciesPredicate(BiPredicate<Individual<T>,Individual<T>> value)

Copy the current immutable object by setting a value for the speciesPredicate attribute. A shallow reference equality check is used to prevent copying of the same value by returning this.

Parameters:

value - A new value for speciesPredicate

Returns:

A modified copy of the this object

withSpeciesSelection

public final ImmutableNeatSelection<T> withSpeciesSelection(SelectionPolicy value)

Copy the current immutable object by setting a value for the speciesSelection attribute. A shallow reference equality check is used to prevent copying of the same value by returning this.

Parameters:

value - A new value for speciesSelection

Returns:

A modified copy of the this object

equals

public boolean equals(Object another)

This instance is equal to all instances of ImmutableNeatSelection that have equal attribute values.

Overrides:

equals in class Object

Returns:

true if this is equal to another instance

equalTo

private boolean equalTo(int synthetic,
 ImmutableNeatSelection<?> another)

hashCode

public int hashCode()

Computes a hash code from attributes: perSpeciesKeepRatio, minSpeciesSize, speciesPredicate, speciesSelection.

Overrides:

hashCode in class Object

Returns:

hashCode value

toString

public String toString()

Prints the immutable value NeatSelection with attribute values.

Overrides:

toString in class Object

Returns:

A string representation of the value

validate

private static <T extends Comparable<T>>
ImmutableNeatSelection<T> validate(ImmutableNeatSelection<T> instance)

copyOf

public static <T extends Comparable<T>>
ImmutableNeatSelection<T> copyOf(NeatSelection<T> instance)

Creates an immutable copy of a NeatSelection value. Uses accessors to get values to initialize the new immutable instance. If an instance is already immutable, it is returned as is.

Type Parameters:

T - generic parameter T

Parameters:

instance - The instance to copy

Returns:

A copied immutable NeatSelection instance