splitmerge_LSS_SDDS.hpp

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#pragma once
 
#include "../utils/Sampler.hpp"

class SplitMerge_LSS_SDDS : public Sampler {
private:
    // ========== Random Number Generation ==========

    mutable std::mt19937 gen;
 
    // ========== Move Selection Variables ==========

    int idx_i;

    int idx_j;

    int ci;

    int cj;
 
    // ========== Algorithm Configuration ==========

    bool shuffle_bool = false;
 
    // ========== State Management ==========

    Eigen::VectorXi launch_state;

    Eigen::VectorXi S;

    int launch_state_size;

    const Eigen::VectorXi &original_allocations;
 
    // ========== Proposal Probabilities ==========

    std::uniform_real_distribution<> dis_real;

    std::uniform_int_distribution<> dis_int;

    Eigen::Vector2d log_probs;

    Eigen::Vector2d probs;

    double log_split_gibbs_prob = 0;

    double log_merge_gibbs_prob = 0;

    const double rand_split_prob = log(0.5);
 
    // ========== Debug variables ==========
    int accepted_split = 0;
    int accepted_merge = 0;
    int accepted_shuffle = 0;
    int split_moves = 0;
    int merge_moves = 0;
    int shuffle_moves = 0;
 
    // ========== Move Selection Methods ==========

    void choose_indeces(bool similarity = false);

    void choose_clusters_shuffle();
 
    // ========== SAMS-Specific Proposal Generation ==========

    void sequential_allocation(int iterations, bool only_probabilities = false, bool sequential = true);
 
    // ========== Split Move Implementation ==========

    void smart_split_move();

    void dumb_split_move();

    double compute_acceptance_ratio_split(double likelihood_old_cluster);
 
    // ========== Merge Move Implementation ==========

    void smart_merge_move();

    void dumb_merge_move();

    double compute_acceptance_ratio_merge(double likelihood_old_ci, double likelihood_old_cj);
 
    // ========== Shuffle Move Implementation ==========

    void shuffle();

    double compute_acceptance_ratio_shuffle(double likelihood_old_ci, double likelihood_old_cj, int old_ci_size,
                                            int old_cj_size);
 
public:
    // ========== Constructor ==========

    SplitMerge_LSS_SDDS(Data &d, Params &p, Likelihood &l, Process &pr, bool shuffle)
        : Sampler(d, p, l, pr), shuffle_bool(shuffle), original_allocations(pr.old_allocations_view()), gen(rd()),
          dis_real(0.0, 1.0), dis_int(0, 1) {};
 
    // ========== MCMC Interface ==========

    void step() override final;
 
    // ========== Accessor Methods ==========
    double get_accepted_split() const { return static_cast<double>(accepted_split)/split_moves; };

    double get_accepted_merge() const { return static_cast<double>(accepted_merge)/merge_moves; };

    double get_accepted_shuffle() const { return static_cast<double>(accepted_shuffle)/shuffle_moves; };
};