category_tracker.h

 
#ifndef STOCHTREE_CATEGORY_TRACKER_H_
#define STOCHTREE_CATEGORY_TRACKER_H_
 
#include <Eigen/Dense>
#include <stochtree/log.h>
#include <stochtree/meta.h>
 
#include <cmath>
#include <map>
#include <numeric>
#include <random>
#include <set>
#include <string>
#include <vector>
 
namespace StochTree {
 
class SampleCategoryMapper {
 public:
  SampleCategoryMapper(std::vector<int32_t>& group_indices) {
    num_observations_ = group_indices.size();
    observation_indices_ = group_indices;
  }
  
  SampleCategoryMapper(SampleCategoryMapper& other){
    num_observations_ = other.NumObservations();
    observation_indices_.resize(num_observations_);
    for (int i = 0; i < num_observations_; i++) {
      observation_indices_[i] = other.GetCategoryId(i);
    }
  }
 
  inline data_size_t GetCategoryId(data_size_t sample_id) {
    CHECK_LT(sample_id, num_observations_);
    return observation_indices_[sample_id];
  }
 
  inline void SetCategoryId(data_size_t sample_id, int category_id) {
    CHECK_LT(sample_id, num_observations_);
    observation_indices_[sample_id] = sample_id;
  }
  
  inline int NumObservations() {return num_observations_;}
 
 private:
  std::vector<int> observation_indices_;
  data_size_t num_observations_;
};
 
class CategorySampleTracker {
 public:
  CategorySampleTracker(const std::vector<int32_t>& group_indices) {
    int n = group_indices.size();
    indices_ = std::vector<data_size_t>(n);
    std::iota(indices_.begin(), indices_.end(), 0);
 
    auto comp_op = [&](size_t const &l, size_t const &r) { return std::less<data_size_t>{}(group_indices[l], group_indices[r]); };
    std::stable_sort(indices_.begin(), indices_.end(), comp_op);
 
    category_count_ = 0;
    int observation_count = 0;
    for (int i = 0; i < n; i++) {
      bool start_cond = i == 0;
      bool end_cond = i == n-1;
      bool new_group_cond{false};
      if (i > 0) new_group_cond = group_indices[indices_[i]] != group_indices[indices_[i-1]];
      if (start_cond || new_group_cond) {
        category_id_map_.insert({group_indices[indices_[i]], category_count_});
        unique_category_ids_.push_back(group_indices[indices_[i]]);
        node_index_vector_.emplace_back();
        if (i == 0) {
          category_begin_.push_back(i);
        } else {
          category_begin_.push_back(i);
          category_length_.push_back(observation_count);
        }
        observation_count = 1;
        category_count_++;
      } else if (end_cond) {
        category_length_.push_back(observation_count+1);
      } else {
        observation_count++;
      }
      // Add the index to the category's node index vector in either case
      node_index_vector_[category_count_ - 1].emplace_back(indices_[i]);
    }
  }
 
  inline int32_t CategoryNumber(int category_id) {
    return category_id_map_[category_id];
  }
 
  inline data_size_t CategoryBegin(int category_id) {return category_begin_[category_id_map_[category_id]];}
 
  inline data_size_t CategoryEnd(int category_id) {
    int32_t id = category_id_map_[category_id];
    return category_begin_[id] + category_length_[id];
  }
 
  inline data_size_t CategorySize(int category_id) {
    return category_length_[category_id_map_[category_id]];
  }
 
  inline data_size_t NumCategories() {return category_count_;}
 
  std::vector<data_size_t> indices_;
 
  std::vector<data_size_t>& NodeIndices(int category_id) {
    int32_t id = category_id_map_[category_id];
    return node_index_vector_[id];
  }
  
  std::vector<data_size_t>& NodeIndicesInternalIndex(int internal_category_id) {
    return node_index_vector_[internal_category_id];
  }
 
  std::map<int32_t, int32_t>& GetLabelMap() {return category_id_map_;}
 
  std::vector<int32_t>& GetUniqueGroupIds() {return unique_category_ids_;}
 
 private:
  // Vectors tracking indices in each node
  std::vector<data_size_t> category_begin_;
  std::vector<data_size_t> category_length_;
  std::map<int32_t, int32_t> category_id_map_;
  std::vector<int32_t> unique_category_ids_;
  std::vector<std::vector<data_size_t>> node_index_vector_;
  int32_t category_count_;
};
 
} // namespace StochTree
 
#endif // STOCHTREE_CATEGORY_TRACKER_H_