Forest.h

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/*
  Copyright (C) 2002-2019 CERN for the benefit of the ATLAS collaboration
*/
 
#ifndef MVAUtils_Forest_H
#define MVAUtils_Forest_H
 
#include "MVAUtils/ForestBase.h"
#include "NodeImpl.h"
#include <stack>
#include <cmath>
#include <algorithm>
#include <numeric>
#include <iostream>
#include <vector>
 
 
namespace MVAUtils { namespace detail { // helpers
 
    template<typename T>
    inline T sigmoid(T x) { return 1. / (1. + exp(-x)); }

    template<typename Container_t> void applySoftmax(Container_t& x);

    inline std::vector<index_t> computeRight(const std::vector<int>& vars);
 } }
 
namespace MVAUtils
{
    template<typename Node_t>
    class Forest : public IForest
    {
    public:
      virtual float GetTreeResponse(const std::vector<float>& values,
                                    unsigned int itree) const override final;
      virtual float GetTreeResponse(const std::vector<float*>& pointers,
                                    unsigned int itree) const override final;

      virtual float GetOffset() const override { return 0.; }

      virtual float GetRawResponse(
        const std::vector<float>& values) const override final; 
      virtual float GetRawResponse(
        const std::vector<float*>& pointers) const override final;

      // In this class it is equal to the raw-reponse. Derived class should
      // override this.
      virtual float GetResponse(
        const std::vector<float>& values) const override;
      virtual float GetResponse(
        const std::vector<float*>& pointers) const override;

      // Since TMVA and lgbm are identical the common implementation is here:
      // Return the softmax of the sub-forest raw-response
      virtual std::vector<float> GetMultiResponse(
        const std::vector<float>& values,
        unsigned int numClasses) const override;
 
      virtual std::vector<float> GetMultiResponse(
        const std::vector<float*>& pointers,
        unsigned int numClasses) const override;
 
      virtual unsigned int GetNTrees() const override final
      {
        return m_forest.size();
      }
 
      virtual void PrintForest() const override;
 
      virtual void PrintTree(unsigned int itree) const override;

      std::vector<Node_t> GetTree(unsigned int itree) const;
 
    protected:
        float GetTreeResponseFromNode(const std::vector<float>& values, index_t index) const;
        float GetTreeResponseFromNode(const std::vector<float*>& pointers, index_t index) const;

        void newTree(const std::vector<Node_t>& nodes);
 
    private:
        std::vector<index_t> m_forest; 
        std::vector<Node_t> m_nodes; 
    };
 
}
 
#include "Forest.icc"
 
#endif