Logo ROOT  
Reference Guide
rf405_realtocatfuncs.py
Go to the documentation of this file.
1 ## \file
2 ## \ingroup tutorial_roofit
3 ## \notebook
4 ##
5 ## Data and categories: demonstration of real-discrete mapping functions
6 ##
7 ## \macro_code
8 ##
9 ## \date February 2018
10 ## \authors Clemens Lange, Wouter Verkerke (C++ version)
11 
12 import ROOT
13 
14 
15 # Define pdf in x, sample dataset in x
16 # ------------------------------------------------------------------------
17 
18 # Define a dummy PDF in x
19 x = ROOT.RooRealVar("x", "x", 0, 10)
20 a = ROOT.RooArgusBG("a", "argus(x)", x, ROOT.RooFit.RooConst(
21  10), ROOT.RooFit.RooConst(-1))
22 
23 # Generate a dummy dataset
24 data = a.generate(ROOT.RooArgSet(x), 10000)
25 
26 # Create a threshold real -> cat function
27 # --------------------------------------------------------------------------
28 
29 # A RooThresholdCategory is a category function that maps regions in a real-valued
30 # input observable observables to state names. At construction time a 'default'
31 # state name must be specified to which all values of x are mapped that are not
32 # otherwise assigned
33 xRegion = ROOT.RooThresholdCategory(
34  "xRegion", "region of x", x, "Background")
35 
36 # Specify thresholds and state assignments one-by-one.
37 # Each statement specifies that all values _below_ the given value
38 # (and above any lower specified threshold) are mapped to the
39 # category state with the given name
40 #
41 # Background | SideBand | Signal | SideBand | Background
42 # 4.23 5.23 8.23 9.23
43 xRegion.addThreshold(4.23, "Background")
44 xRegion.addThreshold(5.23, "SideBand")
45 xRegion.addThreshold(8.23, "Signal")
46 xRegion.addThreshold(9.23, "SideBand")
47 
48 # Use threshold function to plot data regions
49 # ----------------------------------------------
50 
51 # Add values of threshold function to dataset so that it can be used as
52 # observable
53 data.addColumn(xRegion)
54 
55 # Make plot of data in x
56 xframe = x.frame(ROOT.RooFit.Title(
57  "Demo of threshold and binning mapping functions"))
58 data.plotOn(xframe)
59 
60 # Use calculated category to select sideband data
61 data.plotOn(
62  xframe,
63  ROOT.RooFit.Cut("xRegion==xRegion::SideBand"),
64  ROOT.RooFit.MarkerColor(
65  ROOT.kRed),
66  ROOT.RooFit.LineColor(
67  ROOT.kRed))
68 
69 # Create a binning real -> cat function
70 # ----------------------------------------------------------------------
71 
72 # A RooBinningCategory is a category function that maps bins of a (named) binning definition
73 # in a real-valued input observable observables to state names. The state names are automatically
74 # constructed from the variable name, binning name and the bin number. If no binning name
75 # is specified the default binning is mapped
76 
77 x.setBins(10, "coarse")
78 xBins = ROOT.RooBinningCategory("xBins", "coarse bins in x", x, "coarse")
79 
80 # Use binning function for tabulation and plotting
81 # -----------------------------------------------------------------------------------------------
82 
83 # Print table of xBins state multiplicity. Note that xBins does not need to be an observable in data
84 # it can be a function of observables in data as well
85 xbtable = data.table(xBins)
86 xbtable.Print("v")
87 
88 # Add values of xBins function to dataset so that it can be used as
89 # observable
90 xb = data.addColumn(xBins)
91 
92 # Define range "alt" as including bins 1,3,5,7,9
93 xb.setRange(
94  "alt",
95  "x_coarse_bin1,x_coarse_bin3,x_coarse_bin5,x_coarse_bin7,x_coarse_bin9")
96 
97 # Construct subset of data matching range "alt" but only for the first
98 # 5000 events and plot it on the frame
99 dataSel = data.reduce(ROOT.RooFit.CutRange(
100  "alt"), ROOT.RooFit.EventRange(0, 5000))
101 dataSel.plotOn(xframe, ROOT.RooFit.MarkerColor(ROOT.kGreen),
102  ROOT.RooFit.LineColor(ROOT.kGreen))
103 
104 c = ROOT.TCanvas("rf405_realtocatfuncs", "rf405_realtocatfuncs", 600, 600)
105 xframe.SetMinimum(0.01)
106 ROOT.gPad.SetLeftMargin(0.15)
107 xframe.GetYaxis().SetTitleOffset(1.4)
108 xframe.Draw()
109 
110 c.SaveAs("rf405_realtocatfuncs.png")