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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## Inspired by the tutorial of Paul Gessinger.
12## \macro_image
13## \macro_code
14##
15## \author Alberto Ferro
16
17import ROOT
18
19ROOT.gStyle.SetOptStat(0)
20
21c1 = ROOT.TCanvas("c1", "fit residual simple")
22h1 = ROOT.TH1D("h1", "h1", 50, -5, 5)
23
24h1.FillRandom("gaus", 2000)
25h1.Fit("gaus")
26h1.GetXaxis().SetTitle("x")
27
28rp1 = ROOT.TRatioPlot(h1)
29rp1.Draw()
30rp1.GetLowerRefYaxis().SetTitle("ratio")
31rp1.GetUpperRefYaxis().SetTitle("entries")
32
33c1.Update()
34