TreeBoosterNode.h

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#ifndef TREE_BOOSTER_NODE_H
#define TREE_BOOSTER_NODE_H
 
#include "CNum/DataStructs/DataStructs.h"
#include "CNum/Data/Data.h"
#include "CNum/Model/Tree/TreeDefs.h"
 
#include <vector>
#include <future>
#include <cstring>
 
namespace CNum::Model::Tree {
  struct Split;
  struct DataPartition;
 
  // -------------
  // Tree Node
  // -------------
  
  class TreeBoosterNode {
  private:
    static double get_gain(double gs,
               double hs,
               double gl,
               double hl,
               double gr,
               double hr,
               double reg_lambda = 1.0,
               double gamma = 0);

    static Split split_comparison(std::vector< std::future<Split> > &splits);
  
  public:
    Split _split;
    double _value;
    TreeBoosterNode *_left;
    TreeBoosterNode *_right;

    TreeBoosterNode(TreeBoosterNode *left = nullptr,
            TreeBoosterNode *right = nullptr);
    
    virtual ~TreeBoosterNode();

    static Split find_best_split_hist(const CNum::DataStructs::Matrix<int> &X,
                      std::shared_ptr<CNum::Data::Shelf[]> shelves,
                      const double *g,
                      const double *h,
                      bool histogram_cache,
                      const arena_view_t &hist_view,
                      DataPartition &partition,
                      double weight_decay = 0.0,
                      double reg_lambda = 1.0,
                      double gamma = 0);

    static Split find_best_split_greedy(CNum::DataStructs::Matrix<double> &X,
                        const double *g,
                        const double *h,
                    double weight_decay = 0.0,
                    double reg_lambda = 1.0,
                    double gamma = 0);

    std::string to_json_string();
 
    friend class TreeBooster;
  };
};
 
#endif