io.jenetics.engine

Interface Problem<T,G extends Gene<?,G>,C extends Comparable<? super C>>

Type Parameters:

T - the (native) argument type of the problem fitness function

G - the gene type the evolution engine is working with

C - the result type of the fitness function

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

This interface describes a problem which can be solved by the GA evolution Engine. It connects the actual fitness() function and the needed codec().

final Problem<ISeq<BitGene>, BitGene, Integer> counting = Problem.of( // Native fitness function genes -> (int)genes.stream() .filter(BitGene::getBit) .count(), // Problem encoding Codec.of( Genotype.of(BitChromosome.of(100)), gt -> gt.getChromosome().toSeq() ) );

The example above shows the Ones-Counting problem definition.

Since:

3.4

Version:

4.2

Author:

Franz Wilhelmstötter

See Also:

Codec, Engine

Method Summary

Modifier and Type	Method and Description
Codec<T,G>	codec() Return the codec, which translates the types of the problem domain into types, which can be understand by the evolution Engine.
default T	decode(Genotype<G> genotype) Converts the given Genotype to the target type T.
Function<T,C>	fitness() Return the fitness function of the problem in the native problem domain.
default C	fitness(Genotype<G> genotype) Returns the fitness value for the given argument.
default C	fitness(T arg) Returns the fitness value for the given argument.
static <T,G extends Gene<?,G>,C extends Comparable<? super C>> Problem<T,G,C>	of(Function<T,C> fitness, Codec<T,G> codec) Return a new optimization problem with the given parameters.

Method Detail

fitness

Function<T,C> fitness()

Return the fitness function of the problem in the native problem domain.

Returns:

the fitness function

codec

Codec<T,G> codec()

Return the codec, which translates the types of the problem domain into types, which can be understand by the evolution Engine.

Returns:

the engine codec

decode

default T decode(Genotype<G> genotype)

Converts the given Genotype to the target type T. This is a shortcut for

final Problem<SomeObject, DoubleGene, Double> problem = ... final Genotype<DoubleGene> gt = problem.codec().encoding().newInstance(); final SomeObject arg = problem.decode(gt);

Parameters:

genotype - the genotype to be converted

Returns:

the converted genotype

Throws:

NullPointerException - if the given genotype is null

Since:

4.2

See Also:

Codec.decode(Genotype)

fitness

default C fitness(T arg)

Returns the fitness value for the given argument.

Parameters:

arg - the argument of the fitness function

Returns:

the fitness value

Since:

4.1

fitness

default C fitness(Genotype<G> genotype)

Returns the fitness value for the given argument.

Parameters:

genotype - the argument of the fitness function

Returns:

the fitness value

Since:

4.1

of

static <T,G extends Gene<?,G>,C extends Comparable<? super C>> Problem<T,G,C> of(Function<T,C> fitness,
                                                                                 Codec<T,G> codec)

Return a new optimization problem with the given parameters.

Type Parameters:

T - the (native) argument type of the problem fitness function

G - the gene type the evolution engine is working with

C - the result type of the fitness function

Parameters:

fitness - the problem fitness function

codec - the evolution engine codec

Returns:

a new problem object from the given parameters

Throws:

NullPointerException - if one of the arguments is null