Logo ROOT  
Reference Guide
rf502_wspacewrite.py
Go to the documentation of this file.
1 ## \file
2 ## \ingroup tutorial_roofit
3 ## \notebook -nodraw
4 ##
5 ## Organization and simultaneous fits: creating and writing a workspace
6 ##
7 ## \macro_code
8 ##
9 ## \date February 2018
10 ## \authors Clemens Lange, Wouter Verkerke (C++ version)
11 
12 import ROOT
13 
14 
15 # Create model and dataset
16 # -----------------------------------------------
17 
18 # Declare observable x
19 x = ROOT.RooRealVar("x", "x", 0, 10)
20 
21 # Create two Gaussian PDFs g1(x,mean1,sigma) anf g2(x,mean2,sigma) and
22 # their parameters
23 mean = ROOT.RooRealVar("mean", "mean of gaussians", 5, 0, 10)
24 sigma1 = ROOT.RooRealVar("sigma1", "width of gaussians", 0.5)
25 sigma2 = ROOT.RooRealVar("sigma2", "width of gaussians", 1)
26 
27 sig1 = ROOT.RooGaussian("sig1", "Signal component 1", x, mean, sigma1)
28 sig2 = ROOT.RooGaussian("sig2", "Signal component 2", x, mean, sigma2)
29 
30 # Build Chebychev polynomial p.d.f.
31 a0 = ROOT.RooRealVar("a0", "a0", 0.5, 0., 1.)
32 a1 = ROOT.RooRealVar("a1", "a1", -0.2, 0., 1.)
33 bkg = ROOT.RooChebychev("bkg", "Background", x, ROOT.RooArgList(a0, a1))
34 
35 # Sum the signal components into a composite signal p.d.f.
36 sig1frac = ROOT.RooRealVar(
37  "sig1frac", "fraction of component 1 in signal", 0.8, 0., 1.)
38 sig = ROOT.RooAddPdf(
39  "sig", "Signal", ROOT.RooArgList(sig1, sig2), ROOT.RooArgList(sig1frac))
40 
41 # Sum the composite signal and background
42 bkgfrac = ROOT.RooRealVar("bkgfrac", "fraction of background", 0.5, 0., 1.)
43 model = ROOT.RooAddPdf(
44  "model", "g1+g2+a", ROOT.RooArgList(bkg, sig), ROOT.RooArgList(bkgfrac))
45 
46 # Generate a data sample of 1000 events in x from model
47 data = model.generate(ROOT.RooArgSet(x), 1000)
48 
49 # Create workspace, import data and model
50 # -----------------------------------------------------------------------------
51 
52 # Create a empty workspace
53 w = ROOT.RooWorkspace("w", "workspace")
54 
55 # Import model and all its components into the workspace
56 w.Import(model)
57 
58 # Import data into the workspace
59 w.Import(data)
60 
61 # Print workspace contents
62 w.Print()
63 
64 # Save workspace in file
65 # -------------------------------------------
66 
67 # Save the workspace into a ROOT file
68 w.writeToFile("rf502_workspace.root")
69