JTestChi2_Slice2D.hh

Go to the documentation of this file.

#ifndef __JCOMPAREHISTOGRAMS__JTESTCHI2_SLICE2D__
#define __JCOMPAREHISTOGRAMS__JTESTCHI2_SLICE2D__

#include <istream>
#include <ostream>

#include "JLang/JException.hh"

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

#include "TH1.h"
#include "TH2.h"


/**
 * \author rgruiz, bjung
 */
namespace JCOMPAREHISTOGRAMS {}
namespace JPP { using namespace JCOMPAREHISTOGRAMS; }

namespace JCOMPAREHISTOGRAMS {

  /**
   * Implementation of the Chi2 test for 2D histograms.\n
   * This class is derived from the abstract class JTest_t(). For a general description of the implementation of this and other tests derived from JTest_t(), see its documentation.\n
   * The parameter slice() can have the values x, X, y or Y. The histograms are sliced along the corresponding axis, and the JChi2Test() test is applied to each slice.\n 
   * The input parameter `threshold`, is used to evaluate whether the test is passed or failed for each slice.\n
   * The evaluation is done by comparing the `threshold` value with the result produced by the Chi2 test for each slice. The output of JChi2Test() is a p-value.\n 
   * The parameter `threshold` should therefore be a real value between 0 and 1.
   */
  class JTestChi2_Slice2D: 
    public JTest_t
  { 
  public:
  
    /**
     * Default constructor.
     */  
    JTestChi2_Slice2D() :
      JTest_t("Chi2_Slice2D", "p-Value(chi2)")
    {}

    
    /**
     * Applies Chi2 test for two ROOT TH2 histograms.
     *
     * \param o1 First histogram
     * \param o2 Second histogram
     */
    void test(const TObject* o1, const TObject* o2) override
    {
      using namespace std;
      using namespace JPP;

      const TH2* h1 = dynamic_cast<const TH2*>(o1);
      const TH2* h2 = dynamic_cast<const TH2*>(o2);
    
      if (h1 == NULL || h2 == NULL) {
        THROW(JValueOutOfRange, "JTestChi2_Slice2D::test(): Could not cast given TObjects to TH2");
      }

      TH1* h3 = NULL;

      const char* const h3name = (h1->GetName() == h2->GetName() ?
                                  MAKE_CSTRING(h1->GetName()                            << "_" << testName << "_" << slice) :
                                  MAKE_CSTRING(h1->GetName() << "_VS_" << h2->GetName() << "_" << testName << "_" << slice));
        
      int  nFailures = 0;
      int  nSlices   = 0;
    
      if (slice == 'x' || slice == 'X') {
    
        const int nSlices1 = h1->GetNbinsX();
        const int nSlices2 = h2->GetNbinsX();

        if (nSlices1 != nSlices2) {
          THROW(JValueOutOfRange, "JTestChi2_Slice2D::test(): Histograms with different binning. The objects: " << h1->GetName() << " and " << h2->GetName() << " can not be compared." << endl);
        }

        nSlices = nSlices1;
        
        h3 = h1->ProjectionX(h3name);
        
        for (int i=1 ; i<=nSlices1 ; ++i){

          const std::string sliceName = MAKE_STRING(h3->GetName() << "_" << to_string(i));
             
          const TH1* s1 = h1->ProjectionY(sliceName.c_str(),i,i);
          const TH1* s2 = h2->ProjectionY(sliceName.c_str(),i,i);

          if (!(s1->GetSumOfWeights() > 0 && s2->GetSumOfWeights() > 0)) { continue; }

          const double chi2 = s1->Chi2Test(s2 , options.c_str());

          const bool failed = (options.find("CHI2") != std::string::npos ?
                               (chi2 > threshold ? true : false) :
                               (chi2 < threshold ? true : false));

          if (failed) nFailures++;
        
          h3->SetBinContent(i,chi2); 
        }
            
      } else if (slice == 'y' || slice == 'Y') {
           
        const int nSlices1 = h1->GetNbinsY();
        const int nSlices2 = h2->GetNbinsY();

        if (nSlices1 != nSlices2) {
          THROW(JValueOutOfRange, "JTestChi2_Slice2D::test(): Histograms with different binning. The objects: " << h1->GetName() << " and " << h2->GetName() << " can not be compared." << endl);
        }

        nSlices = nSlices1;

        h3 = h1->ProjectionY(h3name);

        for (int i=1 ; i<=nSlices1 ; ++i){
             
          const std::string sliceName = MAKE_STRING(h3->GetName() << "_" << to_string(i));

          const TH1* s1 = h1->ProjectionX(sliceName.c_str(),i,i);
          const TH1* s2 = h2->ProjectionX(sliceName.c_str(),i,i);

          if (!(s1->GetSumOfWeights() > 0 && s2->GetSumOfWeights() > 0)) { continue; }    

          const double chi2 = s1->Chi2Test (s2 , options.c_str());

          const bool failed = (options.find("CHI2") != std::string::npos ?
                               (chi2 > threshold ? true : false) :
                               (chi2 < threshold ? true : false));;

          if (failed) nFailures++;
        
          h3->SetBinContent(i,chi2);
        }
      }

      const bool passed = (nFailures/nSlices < failuresThreshold);

      const JResultTitle title(testName, resultType, passed , nFailures);
      
      h3->SetTitle(title.getTitle().c_str());
      h3->GetYaxis()->SetTitle(resultType.c_str());      
      
      const JTestResult r(testName,
                          JRootObjectID(MAKE_STRING(h1->GetDirectory()->GetPath() << h1->GetName())),
                          JRootObjectID(MAKE_STRING(h2->GetDirectory()->GetPath() << h1->GetName())),
                          resultType, nFailures, failuresThreshold, h3, passed);
      
      this->push_back(r);
    }

  
    /**
     * Read test parameters from input.
     *
     * \param  in            input stream
     * \return               input stream
     */
    std::istream& read(std::istream& in) override
    {
      using namespace JPP;
      
      in >> threshold >> failuresThreshold >> slice >> options;

      if (threshold < 0.0) {
        THROW(JValueOutOfRange, "JTestChi2_Slice2D::read(): Invalid threshold value " << threshold);    
      }
      
      if (failuresThreshold < 0.0 || failuresThreshold > 1.0) {
        THROW(JValueOutOfRange, "JTestChi2_Slice2D::read(): Invalid failuresThreshold value " << failuresThreshold);
      }
      
      if (slice != 'x' && slice != 'X' && slice != 'y' && slice != 'Y') {
        THROW(JValueOutOfRange, "JTestChi2_Slice2D::read(): Invalid slice option " << slice);
      }

      return in;
    }
    
  
  private:
    
    double      threshold;                         //!< threshold p-value to decide if test is passed.
    double      failuresThreshold;                 //!< threshold p-value to decide if test is passed.
    char        slice;                             //!< axis to slice.
    std::string options;                           //!< options for the ROOT chi2 test.
  };
}
  
#endif