// \file
/// \ingroup tutorial_roofit
/// \notebook -nodraw
/// Likelihood and minimization: setting up a chi^2 fit to a binned dataset
///
/// \macro_output
/// \macro_code
// \author 07/2008 - Wouter Verkerke
//  Modified by M. Shapiro to show problem with Chisq fit with limited range

#include "RooRealVar.h"
#include "RooDataSet.h"
#include "RooGaussian.h"
#include "RooConstVar.h"
#include "RooChebychev.h"
#include "RooAddPdf.h"
#include "RooChi2Var.h"
#include "TCanvas.h"
#include "TAxis.h"
#include "RooPlot.h"
#include "RooFitResult.h"
#include "TText.h"
#include <iostream>

using namespace RooFit;

void rf602_chi2fit_modified()
{

  // S e t u p   m o d e l
   // ---------------------

   // Declare observable x
   RooRealVar x("x", "x", 0, 10);

   // Create two Gaussian PDFs g1(x,mean1,sigma) anf g2(x,mean2,sigma) and their parameters
   RooRealVar mean("mean", "mean of gaussians", 5);
   RooRealVar sigma1("sigma1", "width of gaussians", 0.5);
   RooRealVar sigma2("sigma2", "width of gaussians", 1);

   RooGaussian sig1("sig1", "Signal component 1", x, mean, sigma1);
   RooGaussian sig2("sig2", "Signal component 2", x, mean, sigma2);

   // Build Chebychev polynomial p.d.f.
   RooRealVar a0("a0", "a0", 0.5, 0., 1.);
   RooRealVar a1("a1", "a1", 0.2, 0., 1.);
   RooChebychev bkg("bkg", "Background", x, RooArgSet(a0, a1));

   // Sum the signal components into a composite signal p.d.f.
   RooRealVar sig1frac("sig1frac", "fraction of component 1 in signal", 0.8, 0., 1.);
   RooAddPdf sig("sig", "Signal", RooArgList(sig1, sig2), sig1frac);

   // Sum the composite signal and background
   RooRealVar bkgfrac("bkgfrac", "fraction of background", 0.5, 0., 1.);
   RooAddPdf model("model", "g1+g2+a", RooArgList(bkg, sig), bkgfrac);

   // C r e a t e   b i n n e d   d a t a s e t
   // -----------------------------------------

   RooDataSet *d = model.generate(x, 10000);
   RooDataHist *dh = d->binnedClone();


   x.setRange("R1",2,9);
   
   // Construct a chi^2 of the data and the model.
   // When a p.d.f. is used in a chi^2 fit, the probability density scaled
   // by the number of events in the dataset to obtain the fit function
   // If model is an extended p.d.f, the expected number events is used
   // instead of the observed number of events.
   
   RooFitResult *fitres  = model.chi2FitTo(*dh,DataError(RooAbsData::SumW2),Save());

   //   model.chi2FitTo(*dh);
   TCanvas *c = new TCanvas("test", "test", 800, 400);
   c->Divide(2,2);
   
   c->cd(1);
   RooPlot *xframe = x.frame(Title("Test Chi2FitTo"));
   model.paramOn(xframe, Layout(0.55));
   dh->plotOn(xframe);
   model.plotOn(xframe, LineWidth(3));

   ostringstream myInfo;
   myInfo << "chisq/dof = " << xframe->chiSquare(fitres->floatParsFinal().size());
   string info = myInfo.str();
   TText *txt = new TText(0.8, 400, info.c_str());
   txt->SetTextSize(0.05);
   txt->SetTextColor(kBlue);
   xframe->addObject(txt);
   xframe->Draw();

   c->cd(3);
   fitres = model.fitTo(*dh, Save());
   RooPlot *xframe3 = x.frame(Title("Test. Likelikhood"));
   model.paramOn(xframe3, Layout(0.55));
   dh->plotOn(xframe3);
   model.plotOn(xframe3, LineWidth(3));
   ostringstream myInfo3;
   myInfo3 << "chisq/dof = " << xframe3->chiSquare(fitres->floatParsFinal().size());
   string info3 = myInfo3.str();
   TText *txt3 = new TText(0.8, 400, info3.c_str());
   txt3->SetTextSize(0.05);
   txt3->SetTextColor(kBlue);
   xframe3->addObject(txt3);
   xframe3->Draw();


   c->cd(2);
   fitres = model.chi2FitTo(*dh,Range("R1"),DataError(RooAbsData::SumW2), Save());

   RooPlot *xframe1 = x.frame(Title("Test.Chi2FitTo Limited range"));
   model.paramOn(xframe1, Layout(0.55));
   dh->plotOn(xframe1);
   model.plotOn(xframe1, LineWidth(3));
   ostringstream myInfo1;
   myInfo1 << "chisq/dof = " << xframe1->chiSquare(fitres->floatParsFinal().size());
   string info1 = myInfo1.str();
   TText *txt1 = new TText(0.8, 400, info1.c_str());
   txt1->SetTextSize(0.05);
   txt1->SetTextColor(kBlue);
   xframe1->addObject(txt1);
   xframe1->Draw();
   
   c->cd(4);
   fitres = model.fitTo(*dh,Range("R1"), Save());
   RooPlot *xframe4 = x.frame(Title("Test. Likelikhood Limited Range"));
   model.paramOn(xframe4, Layout(0.55));
   dh->plotOn(xframe4);
   model.plotOn(xframe4, Range("R1"), NormRange("R1"), LineWidth(3));
   ostringstream myInfo4;
   myInfo4 << "chisq/dof = " << xframe4->chiSquare(fitres->floatParsFinal().size());
   string info4 = myInfo4.str();
   TText *txt4 = new TText(0.8, 400, info.c_str());
   txt4->SetTextSize(0.05);
   txt4->SetTextColor(kBlue);
   xframe4->addObject(txt4);
   xframe4->Draw();
}