source: trunk/c++_tools/classifier/Target.h @ 675

#ifndef _theplu_classifier_target_ 
#define _theplu_classifier_target_ 

// $Id$

/*
  Copyright (C) The authors contributing to this file.

  This file is part of the yat library, http://lev.thep.lu.se/trac/yat

  The yat library is free software; you can redistribute it and/or
  modify it under the terms of the GNU General Public License as
  published by the Free Software Foundation; either version 2 of the
  License, or (at your option) any later version.

  The yat library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  02111-1307, USA.
*/

#include "yat/utility/Exception.h"

#include <cassert>
#include <map>
#include <string>
#include <vector>

#include <iostream>

namespace theplu {
namespace classifier {  

  ///
  /// Class for targets
  ///

  class Target
  {
  
  public:
    ///
    /// @brief Constructor creating target with @a labels
    ///
    explicit Target(const std::vector<std::string>& labels);

    ///
    /// @brief istream constructor.
    ///
    Target(std::istream&, char sep='\0') 
      throw (utility::IO_error,std::exception);

    ///
    /// @brief Copy Constructor 
    ///
    //inline Target(const Target& other) 
    //  : classes_(other.classes_), class_map_(other.class_map_), 
    //    labels_(other.labels_) {}

    ///
    /// Constructor creating a sub-Target from Target @a org. @a vec
    /// defines which indices to use.
    ///
    /// @note class is preserved, i.e., operator() returns the same
    /// for the Target as the original Target.
    ///
    Target(const Target& org, const std::vector<size_t>& vec);

    ///
    /// @brief Destructor
    ///
    ~Target();

    ///
    /// @return a map with label as key and class as value.
    ///
    inline const std::map<std::string,size_t>& classes(void) const 
    { return class_map_; }
    
    ///
    /// This function is equivalent to Target::classes().size()
    ///
    /// @return number of classes
    ///
    inline const size_t nof_classes(void) const { return classes().size(); }

    ///
    /// Default binary is set to false for all classes except class 0.
    ///
    /// @return binary target for sample @a i
    ///
    /// @see set_binary
    ///
    inline bool binary(const size_t i) const 
    { assert(i<size()); return binary_[operator()(i)]; }
    
    ///
    /// @return vector of labels for classes
    ///
    inline const std::vector<std::string>& labels() { return labels_; }

    ///
    /// Binary target for each sample with class @a i is set to @a
    /// b. Default is binary set to false for each class except class
    /// 0 which is set to true.
    ///
    inline void set_binary(const size_t i, const bool b) 
    { assert(i<nof_classes()); binary_[i]=b; }

    ///
    /// @brief randomize labels
    ///
    /// Randomizes classes. Number of samples with a specific label is
    /// not modified, neither mapping from label to class.
    ///
    void random_shuffle(void);

    ///
    /// @return number of samples
    ///
    inline size_t size(void) const { return classes_.size(); }

    ///
    /// @return number of samples with label @a label
    ///
    const size_t size(const std::string& label) const;

    ///
    /// @return number of samples with class @a cl
    ///
    const size_t size(size_t cl) const;


    ///
    /// @return the class of @a sample
    ///
    inline size_t operator()(const size_t sample) const 
    { assert(sample<size()); return classes_[sample]; }
    
    ///
    /// @return the class of @a sample
    ///
    inline size_t operator[](const size_t sample) const 
    { return this->operator()(sample); }

    ///
    /// @brief assignment operator
    ///
    const Target& operator=(const Target&);

  private:
    // binary target for class i
    std::vector<char> binary_; // avoid using vector<bool>
    std::vector<size_t> classes_; // class of sample i
    // map between class label and class index (inverse of labels_)
    std::map<std::string,size_t> class_map_;  
    std::vector<std::string> labels_; // label of class i
    
    void init(const std::vector<std::string>&);

  };  
  
  ///
  /// The output operator for the Target class.
  ///
  std::ostream& operator<<(std::ostream&, const Target& );

}} // of namespace classifier and namespace theplu

#endif