/* **********************************************
 * MVA variable transformation interface.       *
 * Principal Components Analysis (PCA).         *
 * Author: M.Babai@rug.nl                       *
 * LICENSE:                                     *
 * Version:                                     *
 * License:                                     *
 * **********************************************
 */
/*
 * This code is directly based on the Cern Root implementation of PCA.
*/

#ifndef PND_MVA_VAR_PCA_TRANSFORM_H
#define PND_MVA_VAR_PCA_TRANSFORM_H

// C & C++ includes
#include <cassert>
#include <cstdlib>
#include <iostream>
#include <vector>
#include <utility>

// ROOT includes.
#include "TPrincipal.h"

class PndMvaVarPCATransform
{
 public:
  //! Constructor
  PndMvaVarPCATransform();

  //! Destructor.
  virtual ~PndMvaVarPCATransform();
  
  /**
   * Prepare Transformation for the given dataset events.
   *@param dat Collection of the event feature vectors.
   */
  bool InitPCATranformation(std::vector<std::pair<std::string, std::vector<float>*> > const& dat);
  
  /**
   * Transforms the current event variables
   *@param evd Vector containing the event to transform.
   *@return Transformed event.
   */
  std::vector<float>* Transform(std::vector<float> const& evd) const;

  //! Get mean values vector
  inline TVectorD const& GetMeanValues() const;

  //! Get Eigenvectors matrix.
  inline TMatrixD const& GetEigenVectors() const;

  //! Set mean values vector.
  void SetMeanVector(TVectorD const& vect);

  //! Set Eigenvectors matrix.
  void SetEigenVectors(TMatrixD const& mat);

 private:
  //! To avoid mistakes.
  PndMvaVarPCATransform (PndMvaVarPCATransform const& ot);
  PndMvaVarPCATransform &operator=(PndMvaVarPCATransform const& ot);
  
  /*
   * Given a list of n-dimensional data points, Computes PCA for the
   * current dataset.
   */
  void ComputePrincipalComponents(std::vector< std::pair<std::string, std::vector<float>*> > const& dat);
  
  // Mean values
  TVectorD* m_MeanValues;

  // Eigenvectors
  TMatrixD* m_EigenVectors;
};
// ENd of interface definition

/**
 * Get mean values vector.
 */
inline TVectorD const& PndMvaVarPCATransform::GetMeanValues() const
{
  return *m_MeanValues;
}

/**
 * Get Eigenvectors matrix.
 */
inline TMatrixD const& PndMvaVarPCATransform::GetEigenVectors() const
{
  return *m_EigenVectors;
}
#endif