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rf302_utilfuncs.py
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1## \file
2## \ingroup tutorial_roofit
3## \notebook
4## Multidimensional models: utility functions classes available for use in tailoring of
5## composite (multidimensional) pdfs
6##
7## \macro_code
8##
9## \date February 2018
10## \authors Clemens Lange, Wouter Verkerke (C++ version)
11
12import ROOT
13
14# Create observables, parameters
15# -----------------------------------------------------------
16
17# Create observables
18x = ROOT.RooRealVar("x", "x", -5, 5)
19y = ROOT.RooRealVar("y", "y", -5, 5)
20
21# Create parameters
22a0 = ROOT.RooRealVar("a0", "a0", -1.5, -5, 5)
23a1 = ROOT.RooRealVar("a1", "a1", -0.5, -1, 1)
24sigma = ROOT.RooRealVar("sigma", "width of gaussian", 0.5)
25
26# Using RooFormulaVar to tailor pdf
27# -----------------------------------------------------------------------
28
29# Create interpreted function f(y) = a0 - a1*sqrt(10*abs(y))
30fy_1 = ROOT.RooFormulaVar("fy_1", "a0-a1*sqrt(10*abs(y))", [y, a0, a1])
31
32# Create gauss(x,f(y),s)
33model_1 = ROOT.RooGaussian("model_1", "Gaussian with shifting mean", x, fy_1, sigma)
34
35# Using RooPolyVar to tailor pdf
36# -----------------------------------------------------------------------
37
38# Create polynomial function f(y) = a0 + a1*y
39fy_2 = ROOT.RooPolyVar("fy_2", "fy_2", y, [a0, a1])
40
41# Create gauss(x,f(y),s)
42model_2 = ROOT.RooGaussian("model_2", "Gaussian with shifting mean", x, fy_2, sigma)
43
44# Using RooAddition to tailor pdf
45# -----------------------------------------------------------------------
46
47# Create sum function f(y) = a0 + y
48fy_3 = ROOT.RooAddition("fy_3", "a0+y", [a0, y])
49
50# Create gauss(x,f(y),s)
51model_3 = ROOT.RooGaussian("model_3", "Gaussian with shifting mean", x, fy_3, sigma)
52
53# Using RooProduct to tailor pdf
54# -----------------------------------------------------------------------
55
56# Create product function f(y) = a1*y
57fy_4 = ROOT.RooProduct("fy_4", "a1*y", [a1, y])
58
59# Create gauss(x,f(y),s)
60model_4 = ROOT.RooGaussian("model_4", "Gaussian with shifting mean", x, fy_4, sigma)
61
62# Plot all pdfs
63# ----------------------------
64
65# Make two-dimensional plots in x vs y
66hh_model_1 = model_1.createHistogram("hh_model_1", x, Binning=50, YVar=dict(var=y, Binning=50))
67hh_model_2 = model_2.createHistogram("hh_model_2", x, Binning=50, YVar=dict(var=y, Binning=50))
68hh_model_3 = model_3.createHistogram("hh_model_3", x, Binning=50, YVar=dict(var=y, Binning=50))
69hh_model_4 = model_4.createHistogram("hh_model_4", x, Binning=50, YVar=dict(var=y, Binning=50))
70hh_model_1.SetLineColor(ROOT.kBlue)
71hh_model_2.SetLineColor(ROOT.kBlue)
72hh_model_3.SetLineColor(ROOT.kBlue)
73hh_model_4.SetLineColor(ROOT.kBlue)
74
75# Make canvas and draw ROOT.RooPlots
76c = ROOT.TCanvas("rf302_utilfuncs", "rf302_utilfuncs", 800, 800)
77c.Divide(2, 2)
78c.cd(1)
79ROOT.gPad.SetLeftMargin(0.20)
80hh_model_1.GetZaxis().SetTitleOffset(2.5)
81hh_model_1.Draw("surf")
82c.cd(2)
83ROOT.gPad.SetLeftMargin(0.20)
84hh_model_2.GetZaxis().SetTitleOffset(2.5)
85hh_model_2.Draw("surf")
86c.cd(3)
87ROOT.gPad.SetLeftMargin(0.20)
88hh_model_3.GetZaxis().SetTitleOffset(2.5)
89hh_model_3.Draw("surf")
90c.cd(4)
91ROOT.gPad.SetLeftMargin(0.20)
92hh_model_4.GetZaxis().SetTitleOffset(2.5)
93hh_model_4.Draw("surf")
94
95c.SaveAs("rf302_utilfuncs.png")