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Reference Guide
rf309_ndimplot.py
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1 ## \file
2 ## \ingroup tutorial_roofit
3 ## \notebook
4 ## Multidimensional models: making 2/3 dimensional plots of pdfs and datasets
5 ##
6 ## \macro_code
7 ##
8 ## \date February 2018
9 ## \authors Clemens Lange, Wouter Verkerke (C++ version)
10 
11 import ROOT
12 
13 # Create 2D model and dataset
14 # -----------------------------------------------------
15 
16 # Create observables
17 x = ROOT.RooRealVar("x", "x", -5, 5)
18 y = ROOT.RooRealVar("y", "y", -5, 5)
19 
20 # Create parameters
21 a0 = ROOT.RooRealVar("a0", "a0", -3.5, -5, 5)
22 a1 = ROOT.RooRealVar("a1", "a1", -1.5, -1, 1)
23 sigma = ROOT.RooRealVar("sigma", "width of gaussian", 1.5)
24 
25 # Create interpreted function f(y) = a0 - a1*sqrt(10*abs(y))
26 fy = ROOT.RooFormulaVar("fy", "a0-a1*sqrt(10*abs(y))",
27  ROOT.RooArgList(y, a0, a1))
28 
29 # Create gauss(x,f(y),s)
30 model = ROOT.RooGaussian(
31  "model", "Gaussian with shifting mean", x, fy, sigma)
32 
33 # Sample dataset from gauss(x,y)
34 data = model.generate(ROOT.RooArgSet(x, y), 10000)
35 
36 # Make 2D plots of data and model
37 # -------------------------------------------------------------
38 
39 # Create and fill ROOT 2D histogram (20x20 bins) with contents of dataset
40 # hh_data = data.createHistogram("hh_data",x, ROOT.RooFit.Binning(20), ROOT.RooFit.YVar(y, ROOT.RooFit.Binning(20)))
41 # hh_data = data.createHistogram("x,y", 20, 20) # does not work, see
42 # https://root.cern.ch/phpBB3/viewtopic.php?t=16648
43 hh_data = ROOT.RooAbsData.createHistogram(data, "x,y", x, ROOT.RooFit.Binning(
44  20), ROOT.RooFit.YVar(y, ROOT.RooFit.Binning(20)))
45 
46 # Create and fill ROOT 2D histogram (50x50 bins) with sampling of pdf
47 # hh_pdf = model.createHistogram("hh_model",x, ROOT.RooFit.Binning(50), ROOT.RooFit.YVar(y, ROOT.RooFit.Binning(50)))
48 hh_pdf = model.createHistogram("x,y", 50, 50)
49 hh_pdf.SetLineColor(ROOT.kBlue)
50 
51 # Create 3D model and dataset
52 # -----------------------------------------------------
53 
54 # Create observables
55 z = ROOT.RooRealVar("z", "z", -5, 5)
56 
57 gz = ROOT.RooGaussian(
58  "gz", "gz", z, ROOT.RooFit.RooConst(0), ROOT.RooFit.RooConst(2))
59 model3 = ROOT.RooProdPdf("model3", "model3", ROOT.RooArgList(model, gz))
60 
61 data3 = model3.generate(ROOT.RooArgSet(x, y, z), 10000)
62 
63 # Make 3D plots of data and model
64 # -------------------------------------------------------------
65 
66 # Create and fill ROOT 2D histogram (8x8x8 bins) with contents of dataset
67 # hh_data3 = data3.createHistogram("hh_data3", x, ROOT.RooFit.Binning(8), ROOT.RooFit.YVar(y, ROOT.RooFit.Binning(8)), ROOT.RooFit.ZVar(z, ROOT.RooFit.Binning(8)))
68 hh_data3 = ROOT.RooAbsData.createHistogram(
69  data3, "hh_data3", x, ROOT.RooFit.Binning(8), ROOT.RooFit.YVar(
70  y, ROOT.RooFit.Binning(8)), ROOT.RooFit.ZVar(
71  z, ROOT.RooFit.Binning(8)))
72 
73 # Create and fill ROOT 2D histogram (20x20x20 bins) with sampling of pdf
74 hh_pdf3 = model3.createHistogram(
75  "hh_model3", x, ROOT.RooFit.Binning(20), ROOT.RooFit.YVar(
76  y, ROOT.RooFit.Binning(20)), ROOT.RooFit.ZVar(
77  z, ROOT.RooFit.Binning(20)))
78 hh_pdf3.SetFillColor(ROOT.kBlue)
79 
80 c1 = ROOT.TCanvas("rf309_2dimplot", "rf309_2dimplot", 800, 800)
81 c1.Divide(2, 2)
82 c1.cd(1)
83 ROOT.gPad.SetLeftMargin(0.15)
84 hh_data.GetZaxis().SetTitleOffset(1.4)
85 hh_data.Draw("lego")
86 c1.cd(2)
87 ROOT.gPad.SetLeftMargin(0.20)
88 hh_pdf.GetZaxis().SetTitleOffset(2.5)
89 hh_pdf.Draw("surf")
90 c1.cd(3)
91 ROOT.gPad.SetLeftMargin(0.15)
92 hh_data.GetZaxis().SetTitleOffset(1.4)
93 hh_data.Draw("box")
94 c1.cd(4)
95 ROOT.gPad.SetLeftMargin(0.15)
96 hh_pdf.GetZaxis().SetTitleOffset(2.5)
97 hh_pdf.Draw("cont3")
98 c1.SaveAs("rf309_2dimplot.png")
99 
100 c2 = ROOT.TCanvas("rf309_3dimplot", "rf309_3dimplot", 800, 400)
101 c2.Divide(2)
102 c2.cd(1)
103 ROOT.gPad.SetLeftMargin(0.15)
104 hh_data3.GetZaxis().SetTitleOffset(1.4)
105 hh_data3.Draw("lego")
106 c2.cd(2)
107 ROOT.gPad.SetLeftMargin(0.15)
108 hh_pdf3.GetZaxis().SetTitleOffset(1.4)
109 hh_pdf3.Draw("iso")
110 c2.SaveAs("rf309_3dimplot.png")