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Reference Guide
ratioplot2.py
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1 ## \file
2 ## \ingroup tutorial_hist
3 ## \notebook
4 ## Example of a fit residual plot.
5 ##
6 ## Creates a histogram filled with random numbers from a gaussian distribution
7 ## and fits it with a standard gaussian function. The result is passed to the `TRatioPlot`
8 ## constructor. Additionally, after calling `TRatioPlot::Draw` the upper and lower y axis
9 ## titles are modified.
10 ## Confidence interval bands are automatically drawn on the bottom (but can be disabled by draw option `nobands`.
11 ## nspired by the tutorial of Paul Gessinger.
12 ## \macro_image
13 ## \macro_code
14 ##
15 ## \author Alberto Ferro
16 
17 import ROOT
18 
19 ROOT.gStyle.SetOptStat(0)
20 
21 c1 = ROOT.TCanvas("c1", "fit residual simple")
22 h1 = ROOT.TH1D("h1", "h1", 50, -5, 5)
23 
24 h1.FillRandom("gaus", 2000)
25 h1.Fit("gaus")
26 h1.GetXaxis().SetTitle("x")
27 
28 rp1 = ROOT.TRatioPlot(h1)
29 rp1.Draw()
30 rp1.GetLowerRefYaxis().SetTitle("ratio")
31 rp1.GetUpperRefYaxis().SetTitle("entries")
32 
33 c1.Update()
34