source: trunk/yat/statistics/vector_distance.h @ 958

#ifndef theplu_yat_statistics_vector_distance_h
#define theplu_yat_statistics_vector_distance_h

// $Id: vector_distance.h 958 2007-10-10 15:44:06Z peter $

#include <iterator>

#include "yat/classifier/DataLookup1D.h"
#include "yat/classifier/DataLookupWeighted1D.h"
#include "yat/utility/iterator_traits.h"

namespace theplu {
namespace yat {

namespace statistics {
  
  ///
  /// For each measure to calculate distances between containers
  /// with random access iterators one should provide a struct
  /// which inherits from vector_distance_tag and provides a "label" for
  /// the distance measure.
  ///
  struct vector_distance_tag {
    typedef vector_distance_tag distance;
  };


  ///
  /// We are writing a generic function for all distance measures
  /// between containers with random access iterators (below). The
  /// general function does not have to know anything about different
  /// distance measures.  Instead it can access the "label" of each
  /// distance measure through the special template structure
  /// vector_distance_traits.
  ///
  template <class T>
  struct vector_distance_traits {
    typedef typename T::distance distance;
  };


  ///
  /// The general function for calculating distances between vectors
  /// (containers with random access iterators). This general function
  /// calls specialized distance functions implementing various
  /// distance measures based on the "label" of a distance type object
  /// (templatized as Dist). It can also call separate implementations
  /// for iterators to weighted and unweighted iterators based on the
  /// trait of the iterators (templatized as Iter1 and Iter2).
  ///
  template <typename Iter1, typename Iter2, typename Dist>
  double vector_distance(Iter1 beg1, Iter1 end1, Iter2 beg2, const Dist disttag)
  {
    return 
      vector_distance(beg1,end1,beg2,
                      typename vector_distance_traits<Dist>::distance(),
                      typename utility::weighted_if_any2<Iter1, Iter2>::type());
  }       

}}} // of namespace statistics, yat, and theplu

#endif