rf206_treevistools.C

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/// \file
/// \ingroup tutorial_roofit
/// \notebook -nodraw
/// Addition and convolution: tools for visualization of RooAbsArg expression trees
///
/// \macro_output
/// \macro_code
/// \author 07/2008 - Wouter Verkerke

#include "RooRealVar.h"
#include "RooDataSet.h"
#include "RooGaussian.h"
#include "RooChebychev.h"
#include "RooAddPdf.h"
#include "RooExponential.h"
#include "TCanvas.h"
#include "TAxis.h"
#include "RooPlot.h"
using namespace RooFit;

void rf206_treevistools()
{
   // S e t u p   c o m p o s i t e    p d f
   // --------------------------------------

   // 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);

   // 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);

   // Build Chebychev polynomial p.d.f.
   RooRealVar a0("a0", "a0", 0.5, 0., 1.);
   RooRealVar a1("a1", "a1", 0.2, 0., 1.);
   RooChebychev bkg1("bkg1", "Background 1", x, RooArgSet(a0, a1));

   // Build expontential pdf
   RooRealVar alpha("alpha", "alpha", -1);
   RooExponential bkg2("bkg2", "Background 2", x, alpha);

   // Sum the background components into a composite background p.d.f.
   RooRealVar bkg1frac("bkg1frac", "fraction of component 1 in background", 0.2, 0., 1.);
   RooAddPdf bkg("bkg", "Signal", RooArgList(bkg1, bkg2), bkg1frac);

   // 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);

   // P r i n t   c o m p o s i t e   t r e e   i n   A S C I I
   // -----------------------------------------------------------

   // Print tree to stdout
   model.Print("t");

   // Print tree to file
   model.printCompactTree("", "rf206_asciitree.txt");

   // D r a w   c o m p o s i t e   t r e e   g r a p h i c a l l y
   // -------------------------------------------------------------

   // Print GraphViz DOT file with representation of tree
   model.graphVizTree("rf206_model.dot");

   // Make graphic output file with one of the GraphViz tools
   // (freely available from www.graphviz.org)
   //
   // 'Top-to-bottom graph'
   // unix> dot -Tgif -o rf207_model_dot.gif rf207_model.dot
   //
   // 'Spring-model graph'
   // unix> fdp -Tgif -o rf207_model_fdp.gif rf207_model.dot
}