Applying different "mutation strategies" to specific chromosomes in Jenetics

[m4r0lt]

I'm currently working with the Jenetics library to implement a genetic algorithm and I've run into a specific need that I'm not sure how to address. I need to apply different mutation strategies to different chromosomes within the same genotype. Specifically, I want to use a Swap Mutator on the first and third chromosomes, and a Gaussian Mutator on the second and fourth chromosomes.

Here's a basic outline of my genotype structure:
Genotype genotype = Genotype.of(
IntegerChromosome.of(1, 10, 10), // First chromosome
IntegerChromosome.of(1, 3, 10), // Second chromosome
IntegerChromosome.of(1, 10, 10), // Third chromosome
IntegerChromosome.of(1, 5, 10) // Fourth chromosome
);

Could anyone share insights on how to implement this or point me towards any resources or examples that might help?

Thank you in advance for your help!

[jenetics]

The PartialAlterer will do this trick.

final Genotype<IntegerGene> genotype = Genotype.of(
    IntegerChromosome.of(1, 10, 10), // First chromosome
    IntegerChromosome.of(1, 3, 10), // Second chromosome
    IntegerChromosome.of(1, 10, 10), // Third chromosome
    IntegerChromosome.of(1, 5, 10) // Fourth chromosome
);

final Engine<IntegerGene, Double> engine = Engine
    .builder(gt -> gt.gene().doubleValue(), genotype)
    .alterers(
        PartialAlterer.of(new SwapMutator<IntegerGene, Double>(), 0, 2),
        PartialAlterer.of(new GaussianMutator<IntegerGene, Double>(), 1, 3)
    )
    .build();

Regards, Franz

[m4r0lt]

Thank you!

[m4r0lt]

Hello Franz,

Thank you for your previous response, it was quite helpful. After diving deeper into the Jenetics documentation, I understand that a Genotype is expected to have chromosomes of the same type. I initially wanted to combine PermutationChromosome and IntegerChromosome within the same Genotype, but it seems that's not feasible.

My follow-up question is: Is there a way to use IntegerChromosome to simulate the behaviour of PermutationChromosome?

To elaborate, I would like an IntegerChromosome with values ranging from 1 to 10 where the SwapMutator doesn't alter the sequence, thus maintaining a permutation of the original sequence.

For example:
IntegerGene[] genes = new IntegerGene[10];
for (int i = 0; i < 10; i++) {
genes[i] = IntegerGene.of(i + 1, 1, 10);
}
IntegerChromosome chromosome = IntegerChromosome.of(genes);

However, I believe the IntegerChromosome is initialized with random values within the specified range despite setting the allele values manually, which is not the behaviour I expected.

With the PermutationChromosome, I wanted to represent the priorities of tasks/jobs, and thus, the repetition of numbers would not yield the desired 'ideal' representation. Is there a way to configure the IntegerChromosome so it behaves like a PermutationChromosome, or is there a workaround using the SwapMutator that could help me achieve this?

Thank you for your time and assistance.

Best regards, m4r0lt