# Rf 2 0 6_Treevistools¶

Addition and convolution: tools for visualization of RooAbsArg expression trees

Author: Wouter Verkerke
This notebook tutorial was automatically generated with ROOTBOOK-izer from the macro found in the ROOT repository on Monday, January 17, 2022 at 09:54 AM.

In [1]:
%%cpp -d
#include "RooRealVar.h"
#include "RooDataSet.h"
#include "RooGaussian.h"
#include "RooChebychev.h"
#include "RooExponential.h"
#include "TCanvas.h"
#include "TAxis.h"
#include "RooPlot.h"

In [2]:
%%cpp -d
// This is a workaround to make sure the namespace is used inside functions
using namespace RooFit;


## Setup composite pdf¶

Declare observable x

In [3]:
RooRealVar x("x", "x", 0, 10);

RooFit v3.60 -- Developed by Wouter Verkerke and David Kirkby
Copyright (C) 2000-2013 NIKHEF, University of California & Stanford University



Create two gaussian pdfs g1(x,mean1,sigma) anf g2(x,mean2,sigma) and their parameters

In [4]:
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);

[#0] WARNING:InputArguments -- The parameter 'sigma1' with range [-1e+30, 1e+30] of the RooGaussian 'sig1' exceeds the safe range of (0, inf). Advise to limit its range.
[#0] WARNING:InputArguments -- The parameter 'sigma2' with range [-1e+30, 1e+30] of the RooGaussian 'sig2' exceeds the safe range of (0, inf). Advise to limit its range.


Sum the signal components into a composite signal pdf

In [5]:
RooRealVar sig1frac("sig1frac", "fraction of component 1 in signal", 0.8, 0., 1.);
RooAddPdf sig("sig", "Signal", RooArgList(sig1, sig2), sig1frac);


Build chebychev polynomial pdf

In [6]:
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

In [7]:
RooRealVar alpha("alpha", "alpha", -1);
RooExponential bkg2("bkg2", "Background 2", x, alpha);


Sum the background components into a composite background pdf

In [8]:
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

In [9]:
RooRealVar bkgfrac("bkgfrac", "fraction of background", 0.5, 0., 1.);
RooAddPdf model("model", "g1+g2+a", RooArgList(bkg, sig), bkgfrac);


Print tree to stdout

In [10]:
model.Print("t");

0x7fe07aa953d8 RooAddPdf::model = 0.582695 [Auto,Dirty]
0x7fe0900007b0/V- RooChebychev::bkg1 = 0.8 [Auto,Dirty]
0x7fe090000000/V- RooRealVar::a0 = 0.5
0x7fe0900003d8/V- RooRealVar::a1 = 0.2
0x7fe07aa98000/V- RooRealVar::bkg1frac = 0.2
0x7fe0900e89f0/V- RooExponential::bkg2 = 0.00673795 [Auto,Dirty]
0x7fe0900e8618/V- RooRealVar::alpha = -1
0x7fe07aa95000/V- RooRealVar::bkgfrac = 0.5
0x7fe0900e7b88/V- RooGaussian::sig1 = 1 [Auto,Dirty]
0x7fe0900e7000/V- RooRealVar::mean = 5
0x7fe0900e73d8/V- RooRealVar::sigma1 = 0.5
0x7fe0900e80d0/V- RooGaussian::sig2 = 1 [Auto,Dirty]
0x7fe0900e7000/V- RooRealVar::mean = 5
0x7fe0900e77b0/V- RooRealVar::sigma2 = 1


Print tree to file

In [11]:
model.printCompactTree("", "rf206_asciitree.txt");


## Draw composite tree graphically¶

Print graphviz dot file with representation of tree

In [12]:
model.graphVizTree("rf206_model.dot");