JCOMPAREHISTOGRAMS::JTestPoissonLogLikelihoodRatioBeestonBarlow Class Reference

Implementation of the Poisson log-likelihood ratio test. More...

#include <JTestPoissonLogLikelihoodRatioBeestonBarlow.hh>

Inheritance diagram for JCOMPAREHISTOGRAMS::JTestPoissonLogLikelihoodRatioBeestonBarlow:

Public Member Functions
	JTestPoissonLogLikelihoodRatioBeestonBarlow ()
	Default constructor.
void	test (const TObject *o1, const TObject *o2) override
	Applies a Poissonian log-likelihood ratio test to the two given histograms.
std::istream &	read (std::istream &in) override
	Read test parameters from input.
virtual std::ostream &	write (std::ostream &out, const char delimiter=' ', const bool onlyFailures=false) const
	Write test result to output.
virtual void	save (TFile *f, const std::string &path, const bool onlyFailures=false) const
	Writes the test result to root file.
const std::string &	getTestName () const
	Get test name.
const std::string &	getResultType () const
	Get result type.

Protected Attributes
const std::string	testName
	test name
const std::string	resultType
	test result type

Private Attributes
double	threshold
	threshold chi-square to decide if test is passed.

Detailed Description

Implementation of the Poisson log-likelihood ratio test.

The first histogram is treated as an Asimov dataset corresponding to a given null hypothesis,
which is compared to an alternative hypothesis given by the second histogram.

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.

Definition at line 40 of file JTestPoissonLogLikelihoodRatioBeestonBarlow.hh.

Constructor & Destructor Documentation

JTestPoissonLogLikelihoodRatioBeestonBarlow()

JCOMPAREHISTOGRAMS::JTestPoissonLogLikelihoodRatioBeestonBarlow::JTestPoissonLogLikelihoodRatioBeestonBarlow ( )

inline

Default constructor.

Definition at line 48 of file JTestPoissonLogLikelihoodRatioBeestonBarlow.hh.

                                                  :
      JTest_t("Poissonian Log-Likelihood Ratio with Beeston-Barlow Correction", "NLLR")
    {}

Member Function Documentation

test()

void JCOMPAREHISTOGRAMS::JTestPoissonLogLikelihoodRatioBeestonBarlow::test ( const TObject * o1, const TObject * o2 )

inlineoverridevirtual

Applies a Poissonian log-likelihood ratio test to the two given histograms.

The first histogram is treated as an Asimov dataset corresponding to a given null hypothesis.
The second histogram is treated as the expectation for the alternative hypothesis, to which the null hypothesis is compared.

Parameters

o1	First histogram
o2	Second histogram

< Penalty factor

Implements JCOMPAREHISTOGRAMS::JTest_t.

Definition at line 61 of file JTestPoissonLogLikelihoodRatioBeestonBarlow.hh.

    {
      using namespace std;
      using namespace JPP;
 
      static const double penalty = -1e9; //!< Penalty factor      
      
      const TH1* h1 =  dynamic_cast<const TH1*>(o1);
      const TH1* h2 =  dynamic_cast<const TH1*>(o2);
 
      if (h1 == NULL || h2 == NULL) {
        THROW(JValueOutOfRange, "JTestPoissonLogLikelihood::test(): Could not cast given TObjects to TH1.");
      }
 
      if(h1->GetNbinsX() != h2->GetNbinsX() ||
         h1->GetNbinsY() != h2->GetNbinsY() ||
         h1->GetNbinsZ() != h2->GetNbinsZ()) {
        THROW(JValueOutOfRange, "JTestPoissonLogLikelihood::test(): Histograms with different binning. The objects: " <<
              h1->GetName() << " and " << h2->GetName() << " can not be compared." << endl);
      }
 
      RooRealVar x("x", "x", h1->GetBinLowEdge(1), h1->GetBinLowEdge(h1->GetNbinsX()) + h1->GetBinWidth(h1->GetNbinsX()));
 
      RooDataHist dh1("dh1", h1->GetTitle(), x, h1);
      RooDataHist dh2("dh2", h2->GetTitle(), x, h2);
 
#if ROOT_VERSION_CODE < ROOT_VERSION(6,32,0)
      RooParamHistFunc  ph1("ph1", "ph1", dh1);
#else
      RooParamHistFunc  ph1("ph1", "ph1", dh1,x);
#endif
      RooHistConstraint hc1("hc1", "hc1", ph1);
 
      RooRealSumPdf model_tmp1("model_tmp1", "model_tmp1", ph1, RooRealConstant::value(1.0));
      RooProdPdf    model1    ("model1", "model1", hc1, RooFit::Conditional(model_tmp1,x));
      
      RooFitResult* result1 = (RooFitResult*) model1.fitTo(dh2,
                                                           RooFit::SumW2Error(false),
                                                           RooFit::PrintLevel(-1),
                                                           RooFit::Verbose(false),
                                                           RooFit::Save());
      
      if (result1 == NULL) {
        THROW(JValueOutOfRange, "JTestPoissonLogLikelihoodRatioBeestonBarlow::test(): Unable to retrieve fit results");
      }
 
      double nll2 = 0.0; // Poissonian negative log-likelihood of Asimov data-set onto itself
 
      for (int i=1 ; i <= h1->GetNbinsX() ; ++i) {
        for (int j=1 ; j <= h1->GetNbinsY() ; ++j) {
          for (int k=1 ; k <= h1->GetNbinsZ() ; ++k) {
 
            const double n = h2->GetBinContent(i,j,k);
            
            if (n > 0.0) {
              nll2 += -n*log(n) + log(tgamma(n+1)) + n;
            } else {
              nll2 -= penalty;
            }
          }
        }
      }
      
      const double nllratio = 2 * (result1->minNll() - nll2);
      const bool   passed   = (nllratio < threshold);
 
      const JResultTitle title(testName, resultType, passed, nllratio);
 
      TH2* h3 = result1->correlationHist();
      h3->SetTitle(title.getTitle().c_str());
 
      const JTestResult r (testName,
                           JRootObjectID(MAKE_STRING(h1->GetDirectory()->GetPath() << h1->GetName())),
                           JRootObjectID(MAKE_STRING(h2->GetDirectory()->GetPath() << h1->GetName())),
                           resultType, nllratio, threshold, h3, passed);
      
      this->push_back(r);
    }

read()

std::istream & JCOMPAREHISTOGRAMS::JTestPoissonLogLikelihoodRatioBeestonBarlow::read ( std::istream & in )

inlineoverridevirtual

Read test parameters from input.

Parameters

in	input stream

Returns

input stream

Implements JCOMPAREHISTOGRAMS::JTest_t.

Definition at line 147 of file JTestPoissonLogLikelihoodRatioBeestonBarlow.hh.

    {
      using namespace JPP;
      
      in >> threshold;
 
      if (!(threshold > 0.0)) {
        THROW(JValueOutOfRange, "JTestPoissonLogLikelihoodRatioBeestonBarlow::read(): Given chi-square threshold " << threshold << " is invalid");
      }
      
      return in;
    }

write()

virtual std::ostream & JCOMPAREHISTOGRAMS::JTest_t::write ( std::ostream & out, const char delimiter = ' ', const bool onlyFailures = false ) const

inlinevirtualinherited

Write test result to output.

Parameters

out	output stream
delimiter	field delimiter
onlyFailures	if true, write only failures.

Returns

output stream

Definition at line 84 of file JTest_t.hh.

    {
      using namespace std;
      using namespace JPP;
 
      for (vector<JTestResult>::const_iterator r = this->begin() ; r != this->end() ; ++r) {
 
        if (onlyFailures && r->passed) { continue; }
        
        print(out, *r, delimiter, true);
      }
      
      return out;
    }

save()

virtual void JCOMPAREHISTOGRAMS::JTest_t::save ( TFile * f, const std::string & path, const bool onlyFailures = false ) const

inlinevirtualinherited

Writes the test result to root file.

Parameters

f	A ROOT file
path	Path in root file.
onlyFailures	If true, write only failures.

Definition at line 108 of file JTest_t.hh.

    {
      using namespace std;
      using namespace JPP;
 
      if (f->GetDirectory(path.c_str())==0) {
        f->mkdir(path.c_str());
      }
      
      f->cd(path.c_str());
 
      for (vector<JTestResult>::const_iterator r = this->begin() ; r != this->end() ; ++r) {
 
        if (onlyFailures && r->passed) { continue; }
        
        r->obj->Write();
      }
    }

getTestName()

const std::string & JCOMPAREHISTOGRAMS::JTest_t::getTestName ( ) const

inlineinherited

Get test name.

Returns

test name

Definition at line 135 of file JTest_t.hh.

    {
      return testName;
    }

getResultType()

const std::string & JCOMPAREHISTOGRAMS::JTest_t::getResultType ( ) const

inlineinherited

Get result type.

Returns

result type

Definition at line 146 of file JTest_t.hh.

    {
      return resultType;
    }

Member Data Documentation

threshold

double JCOMPAREHISTOGRAMS::JTestPoissonLogLikelihoodRatioBeestonBarlow::threshold

private

threshold chi-square to decide if test is passed.

Definition at line 162 of file JTestPoissonLogLikelihoodRatioBeestonBarlow.hh.

testName

const std::string JCOMPAREHISTOGRAMS::JTest_t::testName

protectedinherited

test name

Definition at line 180 of file JTest_t.hh.

resultType

const std::string JCOMPAREHISTOGRAMS::JTest_t::resultType

protectedinherited

test result type

Definition at line 181 of file JTest_t.hh.

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The documentation for this class was generated from the following file:

• JTestPoissonLogLikelihoodRatioBeestonBarlow.hh