hrntsm/Tunny

using System;

namespace Optuna.Sampler
{
    ///  <summary>
    /// https://optuna.readthedocs.io/en/stable/reference/generated/optuna.samplers.NSGAIISampler.html
    /// </summary>
    public class NSGAIISampler : SamplerBase
    {
        public double? MutationProb { get; set; }
        public int PopulationSize { get; set; } = 50;
        public string Crossover { get; set; } = string.Empty;
        public double CrossoverProb { get; set; } = 0.9;
        public double SwappingProb { get; set; } = 0.5;

        public dynamic ToPython(dynamic optuna, bool hasConstraints)
        {
            return optuna.samplers.NSGAIISampler(
                population_size: PopulationSize,
                mutation_prob: MutationProb,
                crossover_prob: CrossoverProb,
                swapping_prob: SwappingProb,
                seed: Seed,
                crossover: SetCrossover(optuna, Crossover),
                constraints_func: hasConstraints ? ConstraintFunc() : null
            );
        }

        protected static dynamic SetCrossover(dynamic optuna, string crossover)
        {
            switch (crossover)
            {
                case "Uniform":
                    return optuna.samplers.nsgaii.UniformCrossover();
                case "BLXAlpha":
                    return optuna.samplers.nsgaii.BLXAlphaCrossover();
                case "SPX":
                    return optuna.samplers.nsgaii.SPXCrossover();
                case "SBX":
                    return optuna.samplers.nsgaii.SBXCrossover();
                case "VSBX":
                    return optuna.samplers.nsgaii.VSBXCrossover();
                case "UNDX":
                    return optuna.samplers.nsgaii.UNDXCrossover();
                case "":
                    return null;
                default:
                    throw new ArgumentException("Unexpected crossover setting");
            }
        }
    }
}