source: trunk/src/histogram.h @ 40

// $Id: histogram.h 40 2004-02-20 14:03:25Z jari $

#ifndef _THEP_CPPTOOLS_HISTOGRAM_ 
#define _THEP_CPPTOOLS_HISTOGRAM_ 

#include <fstream>
#include <iostream>
#include <string>
#include <gsl/gsl_histogram.h>


namespace thep_cpp_tools
{  
  /**
     Class for binning of data.
  */
  class histogram
  {
  public:
    /**
       Constructor taking three arguments. \n
       nbins = number of bins to split intervall between (uniformly) \n
       min = min-value \n
       max = max-value \n
     */
    histogram( const size_t& nbins, const double& min, const double& max );


    /**
       This function loads a text file into the histogram. The text
       file has two columns. The first is the value and the second is 
       the intensity. 
     */
    void load_from_text_file( const std::string& filename );


    /**
       Returns the intensity corresponding to bin \a n.
     */
    inline double get_intensity( const size_t& n ) const
      { return gsl_histogram_get(h_,n); }


    /**
       Returns the range corresponding to bin \a n 
     */
    inline void get_range( const size_t& n, double& min, double& max ) const
      { gsl_histogram_get_range(h_,n,&min,&max); }


    /**
       Returns the number of bins in the distribution.
     */
    inline size_t get_bins() const { return gsl_histogram_bins(h_); }


    /**
       Returns a random number from the cumulative
       distribution defined by data of histogram.
       (need to run init_probabilities() first). 
       The parameter \a r is the value of the y-axis
       which is between [0,1]. If \a r is drawn from a
       uniform random distribution, the corresponding 
       value out is the random-value of the data in 
       the histogram.
     */
    inline double get_probability( const double& r )
      { return gsl_histogram_pdf_sample(p_,r); }


    /**
       Initialize probability function.
     */
    void init_probabilities();
   
    /**
       standard output operator.
    */
    friend std::ostream& thep_cpp_tools::operator<< 
      ( std::ostream& s_out, const histogram& hist );

    
    /**
       Destructor freeing memory of internal GSL pointers.
     */
    ~histogram();

  private:
    gsl_histogram* h_;
    gsl_histogram_pdf* p_;
  };


}

#endif