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Reference Guide
rf502_wspacewrite.py
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1 ## \file
2 ## \ingroup tutorial_roofit
3 ## \notebook -nodraw
4 ## Organization and simultaneous fits: creating and writing a workspace
5 ##
6 ## \macro_code
7 ##
8 ## \date February 2018
9 ## \authors Clemens Lange, Wouter Verkerke (C++ version)
10 
11 import ROOT
12 
13 
14 # Create model and dataset
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, 0, 10)
23 sigma1 = ROOT.RooRealVar("sigma1", "width of gaussians", 0.5)
24 sigma2 = ROOT.RooRealVar("sigma2", "width of gaussians", 1)
25 
26 sig1 = ROOT.RooGaussian("sig1", "Signal component 1", x, mean, sigma1)
27 sig2 = ROOT.RooGaussian("sig2", "Signal component 2", x, mean, sigma2)
28 
29 # Build Chebychev polynomial pdf
30 a0 = ROOT.RooRealVar("a0", "a0", 0.5, 0., 1.)
31 a1 = ROOT.RooRealVar("a1", "a1", -0.2, 0., 1.)
32 bkg = ROOT.RooChebychev("bkg", "Background", x, ROOT.RooArgList(a0, a1))
33 
34 # Sum the signal components into a composite signal pdf
35 sig1frac = ROOT.RooRealVar(
36  "sig1frac", "fraction of component 1 in signal", 0.8, 0., 1.)
37 sig = ROOT.RooAddPdf(
38  "sig", "Signal", ROOT.RooArgList(sig1, sig2), ROOT.RooArgList(sig1frac))
39 
40 # Sum the composite signal and background
41 bkgfrac = ROOT.RooRealVar("bkgfrac", "fraction of background", 0.5, 0., 1.)
42 model = ROOT.RooAddPdf(
43  "model", "g1+g2+a", ROOT.RooArgList(bkg, sig), ROOT.RooArgList(bkgfrac))
44 
45 # Generate a data sample of 1000 events in x from model
46 data = model.generate(ROOT.RooArgSet(x), 1000)
47 
48 # Create workspace, import data and model
49 # -----------------------------------------------------------------------------
50 
51 # Create a empty workspace
52 w = ROOT.RooWorkspace("w", "workspace")
53 
54 # Import model and all its components into the workspace
55 w.Import(model)
56 
57 # Import data into the workspace
58 w.Import(data)
59 
60 # Print workspace contents
61 w.Print()
62 
63 # Save workspace in file
64 # -------------------------------------------
65 
66 # Save the workspace into a ROOT file
67 w.writeToFile("rf502_workspace.root")
68