HistogramGenerator.h

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#ifndef HistogramGenerator_H
#define HistogramGenerator_H
#include "FastSimulation/Utilities/interface/BaseNumericalRandomGenerator.h"

#include "TH1.h"

class RandomEngine;
class TAxis;

class HistogramGenerator : public BaseNumericalRandomGenerator
{
 public:

   HistogramGenerator(TH1 * histo) :
     BaseNumericalRandomGenerator(histo->GetXaxis()->GetXmin(),
                  histo->GetXaxis()->GetXmax(),
                  100000,
                  3),
     myHisto(histo),
     theXaxis(histo->GetXaxis()),
     nbins(histo->GetXaxis()->GetNbins())
  {

    //    std::cout << "Old xmin/xmax = " << xmin << " " << xmax << std::endl;
    // Drop lowest and highest empty bins 
    double du = (xmax-xmin)/(float)nbins;
    // Restrict xmin to meaningful values
    while ( function(xmin) <= 0. ) xmin += du;
    // Restrict xmax to meaningful values
    while ( function(xmax) <= 0. ) xmax -= du;

    if ( xmin != histo->GetXaxis()->GetXmin() ) xmin -= du;
    if ( xmax != histo->GetXaxis()->GetXmax() ) xmax += du;

    //    std::cout << "New xmin/xmax = " << xmin << " " << xmax << std::endl;

    //    std::cout <<" Init " << std::endl;
    initialize();
  }

  ~HistogramGenerator() override {}

  double function(double x) override { return ersatzt(x); }

 private:
  TH1 * myHisto;

  TAxis * theXaxis;

  int nbins;

   double ersatzt(double x);
};
#endif