rf309_ndimplot.C

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/// \file
/// \ingroup tutorial_roofit
/// \notebook
/// Multidimensional models: making 2/3 dimensional plots of p.d.f.s and datasets
///
/// \macro_image
/// \macro_output
/// \macro_code
/// \author 07/2008 - Wouter Verkerke

#include "RooRealVar.h"
#include "RooDataSet.h"
#include "RooConstVar.h"
#include "RooGaussian.h"
#include "RooProdPdf.h"
#include "TCanvas.h"
#include "TAxis.h"
#include "TH1.h"
#include "RooPlot.h"
using namespace RooFit;

void rf309_ndimplot()
{

   // C r e a t e   2 D   m o d e l   a n d   d a t a s e t
   // -----------------------------------------------------

   // Create observables
   RooRealVar x("x", "x", -5, 5);
   RooRealVar y("y", "y", -5, 5);

   // Create parameters
   RooRealVar a0("a0", "a0", -3.5, -5, 5);
   RooRealVar a1("a1", "a1", -1.5, -1, 1);
   RooRealVar sigma("sigma", "width of gaussian", 1.5);

   // Create interpreted function f(y) = a0 - a1*sqrt(10*abs(y))
   RooFormulaVar fy("fy", "a0-a1*sqrt(10*abs(y))", RooArgSet(y, a0, a1));

   // Create gauss(x,f(y),s)
   RooGaussian model("model", "Gaussian with shifting mean", x, fy, sigma);

   // Sample dataset from gauss(x,y)
   RooDataSet *data = model.generate(RooArgSet(x, y), 10000);

   // M a k e   2 D   p l o t s   o f   d a t a   a n d   m o d e l
   // -------------------------------------------------------------

   // Create and fill ROOT 2D histogram (20x20 bins) with contents of dataset
   // TH2D* hh_data = data->createHistogram("hh_data",x,Binning(20),YVar(y,Binning(20))) ;
   TH1 *hh_data = data->createHistogram("x,y", 20, 20);

   // Create and fill ROOT 2D histogram (50x50 bins) with sampling of pdf
   // TH2D* hh_pdf = model.createHistogram("hh_model",x,Binning(50),YVar(y,Binning(50))) ;
   TH1 *hh_pdf = model.createHistogram("x,y", 50, 50);
   hh_pdf->SetLineColor(kBlue);

   // C r e a t e   3 D   m o d e l   a n d   d a t a s e t
   // -----------------------------------------------------

   // Create observables
   RooRealVar z("z", "z", -5, 5);

   RooGaussian gz("gz", "gz", z, RooConst(0), RooConst(2));
   RooProdPdf model3("model3", "model3", RooArgSet(model, gz));

   RooDataSet *data3 = model3.generate(RooArgSet(x, y, z), 10000);

   // M a k e   3 D   p l o t s   o f   d a t a   a n d   m o d e l
   // -------------------------------------------------------------

   // Create and fill ROOT 2D histogram (8x8x8 bins) with contents of dataset
   TH1 *hh_data3 = data3->createHistogram("hh_data3", x, Binning(8), YVar(y, Binning(8)), ZVar(z, Binning(8)));

   // Create and fill ROOT 2D histogram (20x20x20 bins) with sampling of pdf
   TH1 *hh_pdf3 = model3.createHistogram("hh_model3", x, Binning(20), YVar(y, Binning(20)), ZVar(z, Binning(20)));
   hh_pdf3->SetFillColor(kBlue);

   TCanvas *c1 = new TCanvas("rf309_2dimplot", "rf309_2dimplot", 800, 800);
   c1->Divide(2, 2);
   c1->cd(1);
   gPad->SetLeftMargin(0.15);
   hh_data->GetZaxis()->SetTitleOffset(1.4);
   hh_data->Draw("lego");
   c1->cd(2);
   gPad->SetLeftMargin(0.20);
   hh_pdf->GetZaxis()->SetTitleOffset(2.5);
   hh_pdf->Draw("surf");
   c1->cd(3);
   gPad->SetLeftMargin(0.15);
   hh_data->GetZaxis()->SetTitleOffset(1.4);
   hh_data->Draw("box");
   c1->cd(4);
   gPad->SetLeftMargin(0.15);
   hh_pdf->GetZaxis()->SetTitleOffset(2.5);
   hh_pdf->Draw("cont3");

   TCanvas *c2 = new TCanvas("rf309_3dimplot", "rf309_3dimplot", 800, 400);
   c2->Divide(2);
   c2->cd(1);
   gPad->SetLeftMargin(0.15);
   hh_data3->GetZaxis()->SetTitleOffset(1.4);
   hh_data3->Draw("lego");
   c2->cd(2);
   gPad->SetLeftMargin(0.15);
   hh_pdf3->GetZaxis()->SetTitleOffset(1.4);
   hh_pdf3->Draw("iso");
}