splitmerge_SAMS.hpp

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

class SplitMerge_SAMS : 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;

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

  double log_split_gibbs_prob = 0;

  double log_merge_gibbs_prob = 0;
 
  // ========== Debug variables ==========
  int accepted_split = 0;
  int accepted_merge = 0;
  int accepted_shuffle = 0;
 
  // ========== Move Selection Methods ==========

  void choose_indeces();

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

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

  void split_move();

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

  void 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_SAMS(Data &d, Params &p, Likelihood &l, Process &pr, bool shuffle)
      : Sampler(d, p, l, pr), shuffle_bool(shuffle), gen(rd()) {};
 
  // ========== MCMC Interface ==========

  void step() override;
 
    // ========== Accessor Methods ==========
  int get_accepted_split() const { return accepted_split; };

  int get_accepted_merge() const { return accepted_merge; };

  int get_accepted_shuffle() const { return accepted_shuffle; };
};