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rf509_wsinteractive.py
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1 ## \file
2 ## \ingroup tutorial_roofit
3 ## \notebook
4 ##
5 ## Organization and simultaneous fits: easy interactive access to workspace contents - CINT
6 ## to CLING code migration
7 ##
8 ## \macro_code
9 ##
10 ## \date February 2018
11 ## \authors Clemens Lange, Wouter Verkerke (C++ version)
12 
13 import ROOT
14 
15 
16 def fillWorkspace(w):
17  # Create pdf and fill workspace
18  # --------------------------------------------------------
19 
20  # Declare observable x
21  x = ROOT.RooRealVar("x", "x", 0, 10)
22 
23  # Create two Gaussian PDFs g1(x,mean1,sigma) anf g2(x,mean2,sigma) and
24  # their parameters
25  mean = ROOT.RooRealVar("mean", "mean of gaussians", 5, 0, 10)
26  sigma1 = ROOT.RooRealVar("sigma1", "width of gaussians", 0.5)
27  sigma2 = ROOT.RooRealVar("sigma2", "width of gaussians", 1)
28 
29  sig1 = ROOT.RooGaussian("sig1", "Signal component 1", x, mean, sigma1)
30  sig2 = ROOT.RooGaussian("sig2", "Signal component 2", x, mean, sigma2)
31 
32  # Build Chebychev polynomial p.d.f.
33  a0 = ROOT.RooRealVar("a0", "a0", 0.5, 0., 1.)
34  a1 = ROOT.RooRealVar("a1", "a1", -0.2, 0., 1.)
35  bkg = ROOT.RooChebychev("bkg", "Background", x, ROOT.RooArgList(a0, a1))
36 
37  # Sum the signal components into a composite signal p.d.f.
38  sig1frac = ROOT.RooRealVar(
39  "sig1frac", "fraction of component 1 in signal", 0.8, 0., 1.)
40  sig = ROOT.RooAddPdf(
41  "sig", "Signal", ROOT.RooArgList(
42  sig1, sig2), ROOT.RooArgList(sig1frac))
43 
44  # Sum the composite signal and background
45  bkgfrac = ROOT.RooRealVar("bkgfrac", "fraction of background", 0.5, 0., 1.)
46  model = ROOT.RooAddPdf(
47  "model",
48  "g1+g2+a",
49  ROOT.RooArgList(
50  bkg,
51  sig),
52  ROOT.RooArgList(bkgfrac))
53 
54  w.Import(model)
55 
56 
57 # Create and fill workspace
58 # ------------------------------------------------
59 
60 
61 # Create a workspace named 'w'
62 # With CINT w could exports its contents to
63 # a same-name C++ namespace in CINT 'namespace w'.
64 # but self does not work anymore in CLING.
65 # so self tutorial is an example on how to
66 # change the code
67 w = ROOT.RooWorkspace("w", ROOT.kTRUE)
68 
69 # Fill workspace with p.d.f. and data in a separate function
70 fillWorkspace(w)
71 
72 # Print workspace contents
73 w.Print()
74 
75 # self does not work anymore with CLING
76 # use normal workspace functionality
77 
78 # Use workspace contents
79 # ----------------------------------------------
80 
81 # Old syntax to use the name space prefix operator to access the workspace contents
82 #
83 #d = w.model.generate(w.x,1000)
84 #r = w.model.fitTo(*d)
85 
86 # use normal workspace methods
87 model = w.pdf("model")
88 x = w.var("x")
89 
90 d = model.generate(ROOT.RooArgSet(x), 1000)
91 r = model.fitTo(d)
92 
93 # old syntax to access the variable x
94 # frame = w.x.frame()
95 
96 frame = x.frame()
97 d.plotOn(frame)
98 
99 # OLD syntax to ommit x.
100 # NB: The 'w.' prefix can be omitted if namespace w is imported in local namespace
101 # in the usual C++ way
102 #
103 # using namespace w
104 # model.plotOn(frame)
105 # model.plotOn(frame, ROOT.RooFit.Components(bkg), ROOT.RooFit.LineStyle(ROOT.kDashed))
106 
107 # correct syntax
108 bkg = w.pdf("bkg")
109 model.plotOn(frame)
110 ras_bkg = ROOT.RooArgSet(bkg)
111 model.plotOn(frame, ROOT.RooFit.Components(ras_bkg),
112  ROOT.RooFit.LineStyle(ROOT.kDashed))
113 
114 # Draw the frame on the canvas
115 c = ROOT.TCanvas("rf509_wsinteractive", "rf509_wsinteractive", 600, 600)
116 ROOT.gPad.SetLeftMargin(0.15)
117 frame.GetYaxis().SetTitleOffset(1.4)
118 frame.Draw()
119 
120 c.SaveAs("rf509_wsinteractive.png")