io.jenetics.engine

Interface Constraint<G extends Gene<?,G>,C extends Comparable<? super C>>

All Known Implementing Classes:

RetryConstraint

public interface Constraint<G extends Gene<?,G>,C extends Comparable<? super C>>

This interface allows you to define constraints on single phenotypes. It is a more advanced version of the Phenotype.isValid() method, which checks the validity of the underlying genotypes and/or chromosomes. Additionally it is possible to repair invalid individuals. The evolution Engine is using the constraint in the following way: check the validity and repair invalid individuals.

for (int i = 0; i < population.size(); ++i) { final Phenotype<G, C> individual = population.get(i); if (!constraint.test(individual)) { population.set(i, constraint.repair(individual, generation)); } }

Since:

5.0

Version:

5.0

Author:

Franz Wilhelmstötter

See Also:

Engine.Builder.constraint(Constraint)

API Note:

This class is part of the more advanced API and is not needed for default use cases.

Method Summary

Modifier and Type	Method and Description
static <G extends Gene<?,G>,C extends Comparable<? super C>> Constraint<G,C>	of(Predicate<? super Phenotype<G,C>> validator) Return a new constraint object with the given validator.
static <G extends Gene<?,G>,C extends Comparable<? super C>> Constraint<G,C>	of(Predicate<? super Phenotype<G,C>> validator, BiFunction<? super Phenotype<G,C>,Long,Phenotype<G,C>> repairer) Return a new constraint object with the given validator and repairer.
Phenotype<G,C>	repair(Phenotype<G,C> individual, long generation) Tries to repair the given phenotype.
boolean	test(Phenotype<G,C> individual) Checks the validity of the given individual.

Method Detail

test

boolean test(Phenotype<G,C> individual)

Checks the validity of the given individual.

Parameters:

individual - the phenotype to check

Returns:

true if the given individual is valid, false otherwise

Throws:

NullPointerException - if the given individual is null

repair

Phenotype<G,C> repair(Phenotype<G,C> individual,
                      long generation)

Tries to repair the given phenotype. This method is called by the evolution Engine if the test(Phenotype) method returned false.

Parameters:

individual - the phenotype to repair

generation - the actual generation used for the repaired phenotype

Returns:

a newly created, valid phenotype. The implementation is free to use the given invalid individual as a starting point for the created phenotype.

Throws:

NullPointerException - if the given individual is null

of

static <G extends Gene<?,G>,C extends Comparable<? super C>> Constraint<G,C> of(Predicate<? super Phenotype<G,C>> validator,
                                                                                BiFunction<? super Phenotype<G,C>,Long,Phenotype<G,C>> repairer)

Return a new constraint object with the given validator and repairer.

Type Parameters:

G - the gene type

C - the fitness value type

Parameters:

validator - the phenotype validator used by the constraint

repairer - the phenotype repairer used by the constraint

Returns:

a new constraint strategy

Throws:

NullPointerException - if one of the arguments is null

of

static <G extends Gene<?,G>,C extends Comparable<? super C>> Constraint<G,C> of(Predicate<? super Phenotype<G,C>> validator)

Return a new constraint object with the given validator. The used repairer just creates a new phenotype by using the phenotype to be repaired as template. The repaired phenotype might still be invalid.

Type Parameters:

G - the gene type

C - the fitness value type

Parameters:

validator - the phenotype validator used by the constraint

Returns:

a new constraint strategy

Throws:

NullPointerException - if one of the arguments is null