ratioplot2.py

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## \file
## \ingroup tutorial_hist
## \notebook
## Example of a fit residual plot.
##
## Creates a histogram filled with random numbers from a gaussian distribution
## and fits it with a standard gaussian function. The result is passed to the `TRatioPlot`
## constructor. Additionally, after calling `TRatioPlot::Draw` the upper and lower y axis
## titles are modified.
## Confidence interval bands are automatically drawn on the bottom (but can be disabled by draw option `nobands`.
## nspired by the tutorial of Paul Gessinger.
## \macro_image
## \macro_code
##
## \author Alberto Ferro
 
import ROOT
 
ROOT.gStyle.SetOptStat(0)
 
c1 = ROOT.TCanvas("c1", "fit residual simple")
h1 = ROOT.TH1D("h1", "h1", 50, -5, 5)
 
h1.FillRandom("gaus", 2000)
h1.Fit("gaus")
h1.GetXaxis().SetTitle("x")
 
rp1 = ROOT.TRatioPlot(h1)
rp1.Draw()
rp1.GetLowerRefYaxis().SetTitle("ratio")
rp1.GetUpperRefYaxis().SetTitle("entries")
 
c1.Update()