JTestZero_t.hh

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#ifndef __JTESTZERO_T__
#define __JTESTZERO_T__

#include <istream>
#include <ostream>
#include "TMath.h"
#include "Math/Math.h"
#include "Math/Error.h"
#include "Math/ProbFuncMathCore.h"
#include "Math/SpecFuncMathCore.h"
#include "JCompareHistograms/JTest_t.hh"

/**
 * \author rgruiz
 */

/**
 * Implementation of the Zeros test for histograms with expected low bin contents.
 */
class JTestZero_t
{
public:
  
  /**
   * Default constructor.
   */    
  JTestZero_t(){}
  
  /**
   * Bin-by-Bin test for 2D histograms where a very low number of entries is expected.\n
   * The test loops over all the bins of both histograms and performs the following operations.\n 
   * -Calculates the probability that the observed bin content for histogram A is obtained from a Poisson of parameter 1.\n
   * -Compares the previous result with the threshold value given as an input parameter. The result is true if the probability is higher than the threshold.\n
   * -Calculates the probability that the observed bin content for histogram B is obtained from a Poisson of parameter 1.\n
   * -Compares the previous result with the threshold value given as an input parameter. The result is true if the probability is higher than the threshold.\n
   * -Compares the results from both bins: If both are true, or both are false, the test is passed. If one is true and the other is false, the test is failed.\n
   * At the end of the loop, a failure fraction is computed and compared to the outliersThreshold parameter. If the failure fraction is above the threshold, the test is failed.\n
   * 
   * \param h1 First object
   * \param h2 Second object
   * \param outliersThreshold Fraction of incompatible bins allowed.
   * \param threshold Poisson p-value
   * \param parameterName Name of the parameter used to test the histograms
   * \param testName Name of the test used to compare the histograms
   */
  JTestResult JTestZero_2D(TH2* h1, TH2* h2, double outliersThreshold, double threshold, std::string testName, std::string parameterName) {    

    using namespace std;
    using namespace JPP;
    
    int nx1 = h1->GetNbinsX();
    int nx2 = h2->GetNbinsX();      
    int ny1 = h1->GetNbinsY();
    int ny2 = h2->GetNbinsY();

    if(nx1 != nx2 || ny1 != ny2)
      ERROR("Histograms with different binning. The objects: " << h1->GetName() << " can not be compared." << endl);
        
    TH2D* h3 = (TH2D*)h1->Clone(h1->GetName()==h2->GetName() ?
                                MAKE_CSTRING(to_string(h1->GetName())) :
                                MAKE_CSTRING(to_string(h1->GetName()) + "_VS_" + to_string(h2->GetName())));
    h3->Reset();

    double failures = 0;
    
    for (int i=1 ; i<nx1+1 ; ++i){
      for (int j=1 ; j<ny1+1 ; ++j){
        
        double m = h1 -> GetBinContent(i,j);
        double n = h2 -> GetBinContent(i,j);
        
        double p1 = 1 - ROOT::Math::poisson_cdf(m,1);
        double p2 = 1 - ROOT::Math::poisson_cdf(n,1);   

        if ((p1 > threshold && p2 < threshold) || 
            (p1 < threshold && p2 > threshold)){
          h3->Fill(i,j);
          failures+=1./(nx1*ny1);
        }        
      }
    }

    bool passed;
    
    (failures > outliersThreshold ? passed = false : passed = true);
    
    JResultTitle title(testName, parameterName, passed , failures);
    
    h3->SetTitle(title.getTitle().c_str());
    
    JTestResult r (testName,
                   string (h1->GetDirectory()->GetPath()).append(h1->GetName()),
                   string (h2->GetDirectory()->GetPath()).append(h2->GetName()),
                   h1->GetDirectory()->GetFile()->GetName(),
                   h2->GetDirectory()->GetFile()->GetName(),
                   parameterName, failures, threshold, h3, passed);

    return r;      
  };
}; 
  
#endif