rf503_wspaceread¶

'ORGANIZATION AND SIMULTANEOUS FITS' RooFit tutorial macro #503

Reading and using a workspace

The input file for self macro is generated by rf502_wspaceread.py

Author: Clemens Lange, Wouter Verkerke (C version)
This notebook tutorial was automatically generated with ROOTBOOK-izer from the macro found in the ROOT repository on Wednesday, July 16, 2025 at 03:56 PM.

In [1]:

import ROOT

Read workspace from file¶

Open input file with workspace (generated by rf503_wspacewrite)

In [2]:

f = ROOT.TFile("rf502_workspace_py.root")

Retrieve workspace from file

In [3]:

w = f.Get("w")

Retrieve pdf, data from workspace¶

Retrieve x, and data from workspace

In [4]:

x = w["x"]
model = w["model"]
data = w["modelData"]

Print structure of composite p.d.f.

In [5]:

model.Print("t")

0x56172f8d8860 RooAddPdf::model = 1/1 [Auto,Clean] 
  0x56172fa605f0/V- RooChebychev::bkg = 1 [Auto,Dirty] 
    0x56172a9e9fa0/V- RooRealVar::x = 5
    0x5617272320e0/V- RooRealVar::a0 = 0.5
    0x561727397900/V- RooRealVar::a1 = 0
  0x56172fafe0f0/V- RooRealVar::bkgfrac = 0.5
  0x56172faf0ed0/V- RooAddPdf::sig = 1/1 [Auto,Clean] 
    0x56172fa772e0/V- RooGaussian::sig1 = 1 [Auto,Dirty] 
      0x56172a9e9fa0/V- RooRealVar::x = 5
      0x56172a955300/V- RooRealVar::mean = 5
      0x561728659600/V- RooRealVar::sigma1 = 0.5
    0x561728f2f6d0/V- RooRealVar::sig1frac = 0.8
    0x56172fa84c90/V- RooGaussian::sig2 = 1 [Auto,Dirty] 
      0x56172a9e9fa0/V- RooRealVar::x = 5
      0x56172a955300/V- RooRealVar::mean = 5
      0x56172f08dcc0/V- RooRealVar::sigma2 = 1

Fit model to data, plot model¶

Fit model to data

In [6]:

model.fitTo(data, PrintLevel=-1)

Out[6]:

<cppyy.gbl.RooFitResult object at 0x(nil)>

[#1] INFO:Fitting -- RooAbsPdf::fitTo(model) fixing normalization set for coefficient determination to observables in data
[#1] INFO:Fitting -- using generic CPU library compiled with no vectorizations
[#1] INFO:Fitting -- Creation of NLL object took 10.7748 ms
[#1] INFO:Fitting -- RooAddition::defaultErrorLevel(nll_model_modelData) Summation contains a RooNLLVar, using its error level
[#1] INFO:Minimization -- RooAbsMinimizerFcn::setOptimizeConst: activating const optimization
[#1] INFO:Minimization -- RooAbsMinimizerFcn::setOptimizeConst: deactivating const optimization

Plot data and PDF overlaid

In [7]:

xframe = x.frame(Title="Model and data read from workspace")
data.plotOn(xframe)
model.plotOn(xframe)

Out[7]:

<cppyy.gbl.RooPlot object at 0x5617304f7140>

Overlay the background component of model with a dashed line

In [8]:

model.plotOn(xframe, Components="bkg", LineStyle="--")

Out[8]:

<cppyy.gbl.RooPlot object at 0x5617304f7140>

[#1] INFO:Plotting -- RooAbsPdf::plotOn(model) directly selected PDF components: (bkg)
[#1] INFO:Plotting -- RooAbsPdf::plotOn(model) indirectly selected PDF components: ()

Overlay the background+sig2 components of model with a dotted line

In [9]:

model.plotOn(xframe, Components="bkg,sig2", LineStyle=":")

Out[9]:

<cppyy.gbl.RooPlot object at 0x5617304f7140>

[#1] INFO:Plotting -- RooAbsPdf::plotOn(model) directly selected PDF components: (bkg,sig2)
[#1] INFO:Plotting -- RooAbsPdf::plotOn(model) indirectly selected PDF components: (sig)

Draw the frame on the canvas

In [10]:

c = ROOT.TCanvas("rf503_wspaceread", "rf503_wspaceread", 600, 600)
ROOT.gPad.SetLeftMargin(0.15)
xframe.GetYaxis().SetTitleOffset(1.4)
xframe.Draw()

c.SaveAs("rf503_wspaceread.png")

Info in <TCanvas::Print>: png file rf503_wspaceread.png has been created

Draw all canvases

In [11]:

from ROOT import gROOT 
gROOT.GetListOfCanvases().Draw()