ROOT   Reference Guide
Searching...
No Matches
rf206_treevistools.py
Go to the documentation of this file.
1## \file
2## \ingroup tutorial_roofit
3## \notebook -nodraw
4## Addition and convolution: tools for visualization of ROOT.RooAbsArg expression trees
5##
6## \macro_code
7## \macro_output
8##
9## \date February 2018
10## \authors Clemens Lange, Wouter Verkerke (C++ version)
11
12import ROOT
13
14# Set up composite pdf
15# --------------------------------------
16
17# Declare observable x
18x = ROOT.RooRealVar("x", "x", 0, 10)
19
20# Create two Gaussian PDFs g1(x,mean1,sigma) anf g2(x,mean2,sigma) and
21# their parameters
22mean = ROOT.RooRealVar("mean", "mean of gaussians", 5)
23sigma1 = ROOT.RooRealVar("sigma1", "width of gaussians", 0.5)
24sigma2 = ROOT.RooRealVar("sigma2", "width of gaussians", 1)
25sig1 = ROOT.RooGaussian("sig1", "Signal component 1", x, mean, sigma1)
26sig2 = ROOT.RooGaussian("sig2", "Signal component 2", x, mean, sigma2)
27
28# Sum the signal components into a composite signal pdf
29sig1frac = ROOT.RooRealVar("sig1frac", "fraction of component 1 in signal", 0.8, 0.0, 1.0)
30sig = ROOT.RooAddPdf("sig", "Signal", [sig1, sig2], [sig1frac])
31
32# Build Chebychev polynomial pdf
33a0 = ROOT.RooRealVar("a0", "a0", 0.5, 0.0, 1.0)
34a1 = ROOT.RooRealVar("a1", "a1", -0.2, 0.0, 1.0)
35bkg1 = ROOT.RooChebychev("bkg1", "Background 1", x, [a0, a1])
36
37# Build expontential pdf
38alpha = ROOT.RooRealVar("alpha", "alpha", -1)
39bkg2 = ROOT.RooExponential("bkg2", "Background 2", x, alpha)
40
41# Sum the background components into a composite background pdf
42bkg1frac = ROOT.RooRealVar("bkg1frac", "fraction of component 1 in background", 0.2, 0.0, 1.0)
43bkg = ROOT.RooAddPdf("bkg", "Signal", [bkg1, bkg2], [bkg1frac])
44
45# Sum the composite signal and background
46bkgfrac = ROOT.RooRealVar("bkgfrac", "fraction of background", 0.5, 0.0, 1.0)
47model = ROOT.RooAddPdf("model", "g1+g2+a", [bkg, sig], [bkgfrac])
48
49# Print composite tree in ASCII
50# -----------------------------------------------------------
51
52# Print tree to stdout
53model.Print("t")
54
55# Print tree to file
56model.printCompactTree("", "rf206_asciitree.txt")
57
58# Draw composite tree graphically
59# -------------------------------------------------------------
60
61# Print GraphViz DOT file with representation of tree
62model.graphVizTree("rf206_model.dot")
63
64# Make graphic output file with one of the GraphViz tools
65# (freely available from www.graphviz.org)
66#
67# 'Top-to-bottom graph'
68# unix> dot -Tgif -o rf207_model_dot.gif rf207_model.dot
69#
70# 'Spring-model graph'
71# unix> fdp -Tgif -o rf207_model_fdp.gif rf207_model.dot