multiclass.h

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/**
 * @file multiclass.h
 * @author Ozgur Taylan Turan
 *
 * MultiClass Classifier for binary classifiers
 *
 * TODO:
 *  One vs One classifier
 *  
 */
 
#ifndef MULTICLASS_H
#define MULTICLASS_H
 
namespace algo {
namespace classification {
//-----------------------------------------------------------------------------
// OnevAll : one vs rest classifier. This classifier trains a model for every
// label seperately and uses the best prediction from those for prediction.
//-----------------------------------------------------------------------------
template<class MODEL, class T=DTYPE>
class OnevAll
{
public:
  /**
   * Non-working model 
   */
  OnevAll (  ) = default;
 
  /**
   * @param args    : parameters for the model
   */
  template<class... Args>
  OnevAll ( const size_t& num_class, const Args&... args );
 
 
  /**
   * @param inputs  : X
   * @param labels  : y
   * @param args    : parameters for the model
   */
  template<class... Args>
  OnevAll ( const arma::Mat<T>& inputs,
            const arma::Row<size_t>& labels,
            const size_t& num_class,
            const Args&... args );
 
  /**
   * @param inputs  : X
   * @param labels  : y
   * @param args    : parameters for the model
   */
  template<class... Args>
  void Train ( const arma::Mat<T>& inputs,
               const arma::Row<size_t>& labels,
               const Args&... args );
 
  /**
   * @param inputs  : X
   * @param labels  : y
   * @param args    : parameters for the model
   */
  template<class... Args>
  void Train ( const arma::Mat<T>& inputs,
               const arma::Row<size_t>& labels );
  /**
   * @param inputs  : X*
   * @param preds   : y*
   */
  void Classify ( const arma::Mat<T>& inputs,
                  arma::Row<size_t>& preds ) const ;
  /**
   * @param inputs  : X*
   * @param preds   : y*
   * @param probs   : p*
   */
  void Classify ( const arma::Mat<T>& inputs,
                  arma::Row<size_t>& preds,
                  arma::Mat<T>& probs ) const ;
  /**
   * @param inputs  : X
   * @param labels  : y
   */
  T ComputeError ( const arma::Mat<T>& inputs,
                   const arma::Row<size_t>& labels );
 
  /**
   * @param inputs  : X
   * @param labels  : y
   */
  T ComputeAccuracy ( const arma::Mat<T>& inputs,
                      const arma::Row<size_t>& labels );
 
  std::vector<MODEL> models_;
 
  /**
   * Serialize the model.
   */
  template<typename Archive>
  void serialize ( Archive& ar,
                   const unsigned int /* version */ )
  {
    ar (  cereal::make_nvp("nclass",nclass_),
          cereal::make_nvp("unclass",unclass_),
          cereal::make_nvp("unq",unq_),
          cereal::make_nvp("models",models_),
          cereal::make_nvp("oneclass",oneclass_));
  }
 
private:
  size_t nclass_;  // number of classes of the problem
  size_t unclass_; // unique number of classes observed 
  arma::Row<size_t> unq_; // unique classes observed 
  bool oneclass_ = false; // This is to trigger if you have only one class input
};
 
} // namespace classification
} // namespace algo
 
#include "multiclass_impl.h"
 
#endif