JTestSignificance_t.hh

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#ifndef __JCOMPAREHISTOGRAMS__JTESTSIGNIFICANCE_T__
#define __JCOMPAREHISTOGRAMS__JTESTSIGNIFICANCE_T__

#include <istream>
#include <ostream>

#include "JCompareHistograms/JTest_t.hh"
#include "JCompareHistograms/JResultTitle.hh"

#include "TMath.h"


/**
 * \author bofearraigh
 * \author rgruiz
 */
namespace JCOMPAREHISTOGRAMS {

  using JGIZMO::JRootObjectID;
  
  /*
   *
   * Compares two histograms \f$ H_a \f$ and \f$ H_b \f$ by calculating the average bin significance \n
   *
   * \f[
   * S = \frac{1}{N} \cdot \sum_{i=0}^{N} \frac{|a_i - K \cdot b_i|}{\sqrt{\sigma ^2(a_i) + K^2 \cdot \sigma ^2(b_i)}}
   * \f]
   *
   * where:
   *  - \f$ N \f$ is the number of bins in \f$ H_a \f$ and \f$ H_b \f$.
   *  - \f$ a_i \f$ and \f$ b_i \f$ are the contents of bin \f$ i \f$ in \f$ H_a \f$ and \f$ H_b \f$.
   *  - \f$ K \f$ is a normalisation parameter. It should be interpreted as the integral of \f$ H_a \f$ divided by the integral of \f$ H_b \f$
   *  - \f$ \sigma \f$  is calculated assuming that the bin contents follow Poisson distributions.
   *
   * A threshold value for \f$ S \f$ is used to tag the test as passed or failed.
   */
  class JTestSignificance_t 
  { 
  public:  

    /**
     * Default constructor.
     */  
    JTestSignificance_t(){}

    /**
     * Significance test for histograms.\n
     *
     * \param h1                 First object
     * \param h2                 Second object
     * \param threshold          Significance threshold
     * \param K                  Normalisation parameter   
     * \param parameterName      Name of the parameter used to test the histograms
     * \param testName           Name of the test used to compare the histograms
     *
     * \return Test result.
     */
    template<class T>
    JTestResult JSignificanceTest(T* h1, T* h2, double threshold, double K, std::string testName, std::string parameterName) {    

      using namespace std;
      using namespace JPP;
    
      if(h1 -> GetNbinsX() != h2 -> GetNbinsX())
        ERROR("Histograms with different bining. The objects: " << h1 -> GetName() << " can not be compared." << endl);
        

      T* h3 = (T*)h1->Clone(h1->GetName()==h2->GetName() ?
                            MAKE_CSTRING(to_string(h1->GetName())) :
                            MAKE_CSTRING(to_string(h1->GetName()) + "_VS_" + to_string(h2->GetName())));
    
      h3->Add(h2,-1*K);
    
      double S = 0;

      for (int i=0 ; i < h1->GetNbinsX() ; ++i){
        for (int j=0 ; j< h1->GetNbinsY() ; ++j){
          for (int k=0 ; k< h1->GetNbinsZ() ; ++k){
          
            double a = h1->GetBinContent(i+1,j+1,k+1);
            double b = h2->GetBinContent(i+1,j+1,k+1);

            if(a!=0 || b!=0){  
              S += fabs((a - K*b)/sqrt(a + K*K*b));
            }
          }     
        }
      }

      S /= (h1->GetNbinsX()*h1->GetNbinsY()*h1->GetNbinsZ());

      bool passed;
    
      (S < threshold ? passed = false : passed = true);
    
      JResultTitle title(testName, parameterName, passed, S);
    
      h3->SetTitle(title.getTitle().c_str());
  
      JTestResult r (testName,
                     JRootObjectID(MAKE_STRING(h1->GetDirectory()->GetPath() << h1->GetName())),
                     JRootObjectID(MAKE_STRING(h2->GetDirectory()->GetPath() << h1->GetName())),
                     parameterName, S , threshold, h3, passed);

      return r;
    };
  };
}
  
#endif