Standard demo of the Profile Likelihood calculator StandardProfileLikelihoodDemo
This is a standard demo that can be used with any ROOT file prepared in the standard way. You specify:
With default parameters the macro will attempt to run the standard hist2workspace example and read the ROOT file that it produces.
The actual heart of the demo is only about 10 lines long.
The ProfileLikelihoodCalculator is based on Wilks's theorem and the asymptotic properties of the profile likelihood ratio (eg. that it is chi-square distributed for the true value).
Author: Kyle Cranmer
This notebook tutorial was automatically generated with ROOTBOOK-izer from the macro found in the ROOT repository on Wednesday, April 17, 2024 at 11:21 AM.
%%cpp -d
#include "TFile.h"
#include "TROOT.h"
#include "TSystem.h"
#include "RooWorkspace.h"
#include "RooAbsData.h"
#include "RooRealVar.h"
#include "RooStats/ModelConfig.h"
#include "RooStats/ProfileLikelihoodCalculator.h"
#include "RooStats/LikelihoodInterval.h"
#include "RooStats/LikelihoodIntervalPlot.h"
using namespace RooFit;
using namespace RooStats;
struct ProfileLikelihoodOptions {
double confLevel = 0.95;
int nScanPoints = 50;
bool plotAsTF1 = false;
double poiMinPlot = 1;
double poiMaxPlot = 0;
bool doHypoTest = false;
double nullValue = 0;
};
ProfileLikelihoodOptions optPL;
Arguments are defined.
const char *infile = "";
const char *workspaceName = "combined";
const char *modelConfigName = "ModelConfig";
const char *dataName = "obsData";
double confLevel = optPL.confLevel;
double nScanPoints = optPL.nScanPoints;
bool plotAsTF1 = optPL.plotAsTF1;
double poiXMin = optPL.poiMinPlot;
double poiXMax = optPL.poiMaxPlot;
bool doHypoTest = optPL.doHypoTest;
double nullParamValue = optPL.nullValue;
First part is just to access a user-defined file or create the standard example file if it doesn't exist
const char *filename = "";
if (!strcmp(infile, "")) {
filename = "results/example_combined_GaussExample_model.root";
bool fileExist = !gSystem->AccessPathName(filename); // note opposite return code
// if file does not exists generate with histfactory
if (!fileExist) {
// Normally this would be run on the command line
cout << "will run standard hist2workspace example" << endl;
gROOT->ProcessLine(".! prepareHistFactory .");
gROOT->ProcessLine(".! hist2workspace config/example.xml");
cout << "\n\n---------------------" << endl;
cout << "Done creating example input" << endl;
cout << "---------------------\n\n" << endl;
}
} else
filename = infile;
Try to open the file
TFile *file = TFile::Open(filename);
get the workspace out of the file
RooWorkspace *w = (RooWorkspace *)file->Get(workspaceName);
get the modelConfig out of the file
ModelConfig *mc = (ModelConfig *)w->obj(modelConfigName);
get the modelConfig out of the file
RooAbsData *data = w->data(dataName);
create and use the ProfileLikelihoodCalculator to find and plot the 95% confidence interval on the parameter of interest as specified in the model config
ProfileLikelihoodCalculator pl(*data, *mc);
pl.SetConfidenceLevel(confLevel); // 95% interval
LikelihoodInterval *interval = pl.GetInterval();
print out the interval on the first Parameter of Interest
RooRealVar *firstPOI = (RooRealVar *)mc->GetParametersOfInterest()->first();
cout << "\n>>>> RESULT : " << confLevel * 100 << "% interval on " << firstPOI->GetName() << " is : ["
<< interval->LowerLimit(*firstPOI) << ", " << interval->UpperLimit(*firstPOI) << "]\n " << endl;
make a plot
cout << "making a plot of the profile likelihood function ....(if it is taking a lot of time use less points or the "
"TF1 drawing option)\n";
LikelihoodIntervalPlot plot(interval);
plot.SetNPoints(nScanPoints); // do not use too many points, it could become very slow for some models
if (poiXMin < poiXMax)
plot.SetRange(poiXMin, poiXMax);
TString opt;
if (plotAsTF1)
opt += TString("tf1");
plot.Draw(opt); // use option TF1 if too slow (plot.Draw("tf1")
// if requested perform also an hypothesis test for the significance
if (doHypoTest) {
RooArgSet nullparams("nullparams");
nullparams.addClone(*firstPOI);
nullparams.setRealValue(firstPOI->GetName(), nullParamValue);
pl.SetNullParameters(nullparams);
std::cout << "Perform Test of Hypothesis : null Hypothesis is " << firstPOI->GetName() << nullParamValue
<< std::endl;
auto result = pl.GetHypoTest();
std::cout << "\n>>>> Hypotheis Test Result \n";
result->Print();
}
Draw all canvases
gROOT->GetListOfCanvases()->Draw()