Example #1
0
// Mutates a genome
void Species::MutateGenome( bool t_baby_is_clone, Population &a_Pop, Genome &t_baby, Parameters& a_Parameters, RNG& a_RNG )
{
#if 1
    // NEW version:
    // All mutations are mutually exclusive - can't have 2 mutations at once
    // for example a weight mutation and time constants mutation
    // or add link and add node and then weight mutation
    // We will perform roulette wheel selection to choose the type of mutation and will mutate the baby
    // This method guarantees that the baby will be mutated at least with one mutation
    enum MutationTypes {ADD_NODE = 0, ADD_LINK, REMOVE_NODE, REMOVE_LINK, CHANGE_ACTIVATION_FUNCTION,
                        MUTATE_WEIGHTS, MUTATE_ACTIVATION_A, MUTATE_ACTIVATION_B, MUTATE_TIMECONSTS, MUTATE_BIASES
                       };
    std::vector<int> t_muts;
    std::vector<double> t_mut_probs;

    // ADD_NODE;
    t_mut_probs.push_back( a_Parameters.MutateAddNeuronProb );

    // ADD_LINK;
    t_mut_probs.push_back( a_Parameters.MutateAddLinkProb );

    // REMOVE_NODE;
    t_mut_probs.push_back( a_Parameters.MutateRemSimpleNeuronProb );

    // REMOVE_LINK;
    t_mut_probs.push_back( a_Parameters.MutateRemLinkProb );

    // CHANGE_ACTIVATION_FUNCTION;
    t_mut_probs.push_back( a_Parameters.MutateNeuronActivationTypeProb );

    // MUTATE_WEIGHTS;
    t_mut_probs.push_back( a_Parameters.MutateWeightsProb );

    // MUTATE_ACTIVATION_A;
    t_mut_probs.push_back( a_Parameters.MutateActivationAProb );

    // MUTATE_ACTIVATION_B;
    t_mut_probs.push_back( a_Parameters.MutateActivationBProb );

    // MUTATE_TIMECONSTS;
    t_mut_probs.push_back( a_Parameters.MutateNeuronTimeConstantsProb );

    // MUTATE_BIASES;
    t_mut_probs.push_back( a_Parameters.MutateNeuronBiasesProb );

    // Special consideration for phased searching - do not allow certain mutations depending on the search mode
    // also don't use additive mutations if we just want to get rid of the clones
    if ((a_Pop.GetSearchMode() == SIMPLIFYING) || t_baby_is_clone)
    {
        t_mut_probs[ADD_NODE] = 0; // add node
        t_mut_probs[ADD_LINK] = 0; // add link
    }
    if ((a_Pop.GetSearchMode() == COMPLEXIFYING) || t_baby_is_clone)
    {
        t_mut_probs[REMOVE_NODE] = 0; // rem node
        t_mut_probs[REMOVE_LINK] = 0; // rem link
    }

    bool t_mutation_success = false;

    // repeat until successful
    while (t_mutation_success == false)
    {
        int ChosenMutation = a_RNG.Roulette(t_mut_probs);

        // Now mutate based on the choice
        switch(ChosenMutation)
        {
        case ADD_NODE:
            t_mutation_success = t_baby.Mutate_AddNeuron(a_Pop.AccessInnovationDatabase(), a_Parameters, a_RNG);
            break;

        case ADD_LINK:
            t_mutation_success = t_baby.Mutate_AddLink(a_Pop.AccessInnovationDatabase(), a_Parameters, a_RNG);
            break;

        case REMOVE_NODE:
            t_mutation_success = t_baby.Mutate_RemoveSimpleNeuron(a_Pop.AccessInnovationDatabase(), a_RNG);
            break;

        case REMOVE_LINK:
        {
            // Keep doing this mutation until it is sure that the baby will not
            // end up having dead ends or no links
            Genome t_saved_baby = t_baby;
            bool t_no_links = false, t_has_dead_ends = false;

            int t_tries = 128;
            do
            {
                t_tries--;
                if (t_tries <= 0)
                {
                    t_saved_baby = t_baby;
                    break; // give up
                }

                t_saved_baby = t_baby;
                t_mutation_success = t_saved_baby.Mutate_RemoveLink(a_RNG);

                t_no_links = t_has_dead_ends = false;

                if (t_saved_baby.NumLinks() == 0)
                    t_no_links = true;

                t_has_dead_ends = t_saved_baby.HasDeadEnds();

            }
            while(t_no_links || t_has_dead_ends);

            t_baby = t_saved_baby;

            // debugger trap
            if (t_baby.NumLinks() == 0)
            {
                std::cerr << "No links in baby after mutation" << std::endl;
            }
            if (t_baby.HasDeadEnds())
            {
                std::cerr << "Dead ends in baby after mutation" << std::endl;
            }
        }
        break;

        case CHANGE_ACTIVATION_FUNCTION:
            t_baby.Mutate_NeuronActivation_Type(a_Parameters, a_RNG);
            t_mutation_success = true;
            break;

        case MUTATE_WEIGHTS:
            t_baby.Mutate_LinkWeights(a_Parameters, a_RNG);
            t_mutation_success = true;
            break;

        case MUTATE_ACTIVATION_A:
            t_baby.Mutate_NeuronActivations_A(a_Parameters, a_RNG);
            t_mutation_success = true;
            break;

        case MUTATE_ACTIVATION_B:
            t_baby.Mutate_NeuronActivations_B(a_Parameters, a_RNG);
            t_mutation_success = true;
            break;

        case MUTATE_TIMECONSTS:
            t_baby.Mutate_NeuronTimeConstants(a_Parameters, a_RNG);
            t_mutation_success = true;
            break;

        case MUTATE_BIASES:
            t_baby.Mutate_NeuronBiases(a_Parameters, a_RNG);
            t_mutation_success = true;
            break;

        default:
            t_mutation_success = false;
            break;
        }
    }


#else

    // Old version of the function - added just to test various ways to do mutation

    bool t_mutation_success = false;
    // repeat until successful
    while (t_mutation_success == false)
    {
        if (a_RNG.RandFloat() < a_Parameters.MutateAddNeuronProb)
            t_mutation_success = t_baby.Mutate_AddNeuron(a_Pop.AccessInnovationDatabase(), a_Parameters, a_RNG);
        else
        if (a_RNG.RandFloat() < a_Parameters.MutateAddLinkProb)
            t_mutation_success = t_baby.Mutate_AddLink(a_Pop.AccessInnovationDatabase(), a_Parameters, a_RNG);
        else
        {
            /*if (a_RNG.RandFloat() < a_Parameters.MutateNeuronActivationTypeProb)
            {
                t_baby.Mutate_NeuronActivation_Type(a_Parameters, a_RNG);
                t_mutation_success = true;
            }*/

            if (a_RNG.RandFloat() < a_Parameters.MutateWeightsProb)
            {
                t_baby.Mutate_LinkWeights(a_Parameters, a_RNG);
                t_mutation_success = true;
                break;
            }

            /*case MUTATE_ACTIVATION_A:
                t_baby.Mutate_NeuronActivations_A(a_Parameters, a_RNG);
                t_mutation_success = true;
                break;

            case MUTATE_ACTIVATION_B:
                t_baby.Mutate_NeuronActivations_B(a_Parameters, a_RNG);
                t_mutation_success = true;
                break;

            case MUTATE_TIMECONSTS:
                t_baby.Mutate_NeuronTimeConstants(a_Parameters, a_RNG);
                t_mutation_success = true;
                break;

            case MUTATE_BIASES:
                t_baby.Mutate_NeuronBiases(a_Parameters, a_RNG);
                t_mutation_success = true;
                break;*/
        }
    }

#endif
}