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rf206_treevistools.py
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1 ## \file
2 ## \ingroup tutorial_roofit
3 ## \notebook -nodraw
4 ##
5 ## Addition and convolution: tools for visualization of ROOT.RooAbsArg expression trees
6 ##
7 ## \macro_code
8 ##
9 ## \date February 2018
10 ## \authors Clemens Lange, Wouter Verkerke (C++ version)
11 
12 import ROOT
13 
14 # Set up composite pdf
15 # --------------------------------------
16 
17 # Declare observable x
18 x = 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
22 mean = ROOT.RooRealVar("mean", "mean of gaussians", 5)
23 sigma1 = ROOT.RooRealVar("sigma1", "width of gaussians", 0.5)
24 sigma2 = ROOT.RooRealVar("sigma2", "width of gaussians", 1)
25 sig1 = ROOT.RooGaussian("sig1", "Signal component 1", x, mean, sigma1)
26 sig2 = ROOT.RooGaussian("sig2", "Signal component 2", x, mean, sigma2)
27 
28 # Sum the signal components into a composite signal p.d.f.
29 sig1frac = ROOT.RooRealVar(
30  "sig1frac", "fraction of component 1 in signal", 0.8, 0., 1.)
31 sig = ROOT.RooAddPdf(
32  "sig", "Signal", ROOT.RooArgList(sig1, sig2), ROOT.RooArgList(sig1frac))
33 
34 # Build Chebychev polynomial p.d.f.
35 a0 = ROOT.RooRealVar("a0", "a0", 0.5, 0., 1.)
36 a1 = ROOT.RooRealVar("a1", "a1", -0.2, 0., 1.)
37 bkg1 = ROOT.RooChebychev("bkg1", "Background 1",
38  x, ROOT.RooArgList(a0, a1))
39 
40 # Build expontential pdf
41 alpha = ROOT.RooRealVar("alpha", "alpha", -1)
42 bkg2 = ROOT.RooExponential("bkg2", "Background 2", x, alpha)
43 
44 # Sum the background components into a composite background p.d.f.
45 bkg1frac = ROOT.RooRealVar(
46  "bkg1frac", "fraction of component 1 in background", 0.2, 0., 1.)
47 bkg = ROOT.RooAddPdf(
48  "bkg", "Signal", ROOT.RooArgList(bkg1, bkg2), ROOT.RooArgList(bkg1frac))
49 
50 # Sum the composite signal and background
51 bkgfrac = ROOT.RooRealVar("bkgfrac", "fraction of background", 0.5, 0., 1.)
52 model = ROOT.RooAddPdf(
53  "model", "g1+g2+a", ROOT.RooArgList(bkg, sig), ROOT.RooArgList(bkgfrac))
54 
55 # Print composite tree in ASCII
56 # -----------------------------------------------------------
57 
58 # Print tree to stdout
59 model.Print("t")
60 
61 # Print tree to file
62 model.printCompactTree("", "rf206_asciitree.txt")
63 
64 # Draw composite tree graphically
65 # -------------------------------------------------------------
66 
67 # Print GraphViz DOT file with representation of tree
68 model.graphVizTree("rf206_model.dot")
69 
70 # Make graphic output file with one of the GraphViz tools
71 # (freely available from www.graphviz.org)
72 #
73 # 'Top-to-bottom graph'
74 # unix> dot -Tgif -o rf207_model_dot.gif rf207_model.dot
75 #
76 # 'Spring-model graph'
77 # unix> fdp -Tgif -o rf207_model_fdp.gif rf207_model.dot