text: /*! \file lib/map_utils.h
      Header file for map statistics type
  */
  //C Copyright (C) 2000-2004 Kevin Cowtan and University of York
  //C Copyright (C) 2000-2005 Kevin Cowtan and University of York
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  #ifndef CLIPPER_MAP_UTILS
  #define CLIPPER_MAP_UTILS
  
  
  #include "derivs.h"
  
  
  namespace clipper
  {
  
    //! Generic map statistics class
    /*! This class is used to calculate and store the mean and standard
      deviation of a generic map object of scalar types (e.g. Xmap,
      NXmap). If the map contains NaN values, those points are excluded
      for the calculation. In the case of an Xmap, the proper
      multiplicty corrections are applied to give statistics for a whole
      unit cell */
    class Map_stats
    { 
    public:
      //! Constructor: from Xmap
      template<class M> Map_stats( const M& map );
      const ftype& mean() const { return mean_; }        //!< Mean of map
      const ftype& std_dev() const { return std_dev_; }  //!< Std deviation of map
    private:
      ftype mean_, std_dev_;
    };
  
  
    //! Generic map sorting class
    /*! This class is used to sort a vector of integer indices into a
      map. This includes sorting the whole map to get highest or lowest
      density first, or sorting some subset, e.g. a list of peak
      indices. Integer indices are used because they are the most
      compact way of referencing a unique map location. e.g.
      \code
      clipper::Xmap<float>::Map_reference_index ix;
      std::vector<int> index;
      for ( ix = xmap.first(); !ix.last(); ix.next() )
        index.push_back( ix.index() );
      Map_index_sort::sort_decreasing( xmap, index );
      \endcode
    */
    class Map_index_sort
    {
    public:
      //! Sort a list into increasing order
      template<class M> static void sort_increasing( const M& map, std::vector<int>& index );
      //! Sort a list into decreasing order
      template<class M> static void sort_decreasing( const M& map, std::vector<int>& index );
      //! Internal helper class used for sorting
    private:
      template<class M> class Compare_density {
      public:
        Compare_density( const M& m ) { p = &m; }
        bool operator() ( const int& i1, const int& i2 ) const { return p->get_data(i1) < p->get_data(i2); }
      private:
        const M* p;
      };
    };
  
  
    // template implementations
  
    /*! For float and double maps
      \params map The map for which moments are to be calculated. */
    template<class M> Map_stats::Map_stats( const M& map )
    {
      ftype64 w, x, s, sx, sxx;
      s = sx = sxx = 0.0;
      for ( typename M::Map_reference_index im = map.first();
  	  !im.last(); im.next() ) {
        w = 1.0 / ftype64( map.multiplicity( im.coord() ) );
        x = ftype64( map[im] );
        if ( !Util::is_nan(x) ) {
  	s += w;
  	sx += w*x;
  	sxx += w*x*x;
        }
      }
      sx /= s;
      sxx /= s;
      mean_ = sx;
      std_dev_ = sqrt( sxx - sx*sx );
    }
  
  
  } // namespace clipper
  
  #endif
  