using namespace RooFit ;

void ex8()
{
  // A likelihood fit for efficiency    

  RooWorkspace w("w",kTRUE) ;

  // Given an efficiency function
  w.factory("expr::effFunc('offset+0.5*emax*(1+TMath::Erf((x-mean)/sigma))',x[0,100],offset[0.02,0,1],emax[0.78,0,1],mean[60,0,100],sigma[20,1,100])") ;
  w.var("x")->setBins(20) ;

  // Generate a mock data set (also needs a choice of distribution in x
  Int_t N(1000) ;
  w.factory("cut[reject,accept]") ;
  w.factory("Exponential::shape(x,-0.01)") ;
  w.factory("EffProd::genacc(shape,effFunc)") ;
  w.factory("EffProd::genrej(shape,expr('1-@0',effFunc))") ;  
  RooDataSet* data_acc = w.pdf("genacc")->generate(*w.var("x"), N*0.256) ;
  RooDataSet* data_rej = w.pdf("genrej")->generate(*w.var("x"), N*0.744) ;

  // Make a 1D histogram of efficiency
  TH1* hacc = data_acc->createHistogram("x",20) ;
  TH1* htot = data_rej->createHistogram("x",20) ;
  htot->Add(hacc) ;
  hacc->Divide(hacc,htot,1,1,"B") ;

  // Draw efficiency histogram
  TCanvas* c = new TCanvas("c","c",900,300) ;
  c->Divide(3) ;
  c->cd(1) ; 



  // Chi^2 fit of efficiency function to histogram with symmetric Binomial errors
  TF1* fitfunc = new TF1("fitfunc","[0]+[1]*0.5*(1+TMath::Erf((x-[2])/[3]))",0,100) ;
  fitfunc->SetParameters(0.05,0.78,60,20) ;
  hacc->Fit(fitfunc) ;
  

  // BLOCK 1
  //
  // Likelihood fit for efficiency
      
//   // Make a 2D unbinned dataset (x,cut) ;
//   RooDataSet data("data","data",*w.var("x"),Index(*w.cat("cut")),Import("accept",*data_acc),Import("reject",*data_rej)) ;
//   RooPlot* frame2 = w.var("x")->frame() ;
//   data->plotOn(frame2) ;
//   data->plotOn(frame2,Cut("cut==cut::accept"),MarkerColor(kRed),LineColor(kRed)) ;
//
//   // Make unbinned ML fit of efficiency to 2D dataset
//   w.factory("Efficiency::fitmodel(effFunc,cut,'accept')") ;
//   RooFitResult* r = w.pdf("fitmodel")->fitTo(data,ConditionalObservables(*w.var("x")),Save()) ;
//
//   // Make corresponding plot
//   RooPlot* frame3 = w.var("x")->frame() ;
//   data->plotOn(frame3,Efficiency(*w.cat("cut"))) ;
//   w.function("effFunc")->plotOn(frame3,LineColor(kRed)) ;
//   w.function("effFunc")->plotOn(frame3,LineColor(kRed),VisualizeError(*r),FillColor(kOrange),MoveToBack()) ;
//
//   c->cd(2) ; frame2->Draw() ;
//   c->cd(3) ; frame3->Draw() ;


}