VariableSelection.hpp

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#pragma once
 
#include "models/Projector.hpp"
#include "models/strategies/Strategy.hpp"
#include "stats/Stats.hpp"
 
#include <vector>

namespace ppforest2 {
  struct NodeContext;
}
 
namespace ppforest2::vars {
  class VariableSelection : public Strategy<VariableSelection> {
  public:
    struct Result {
      std::vector<int> selected_cols;
      size_t original_size = 0;
 
      Result() = default;
 
      Result(std::vector<int> const& selected_cols, size_t original_size)
          : selected_cols(selected_cols)
          , original_size(original_size) {}

      ::ppforest2::pp::Projector expand(::ppforest2::pp::Projector const& reduced_vector) const {
        ::ppforest2::pp::Projector full_vector = ::ppforest2::pp::Projector::Zero(original_size);
 
        for (size_t i = 0; i < selected_cols.size(); ++i) {
          full_vector(selected_cols[i]) = reduced_vector(i);
        }
 
        return full_vector;
      }
    };

    void select(NodeContext& ctx, stats::RNG& rng) const;
 
  protected:
    virtual void compute(NodeContext& ctx, stats::RNG& rng) const = 0;
  };

  VariableSelection::Ptr all();

  VariableSelection::Ptr uniform(int n_vars);
}