hist031_TRatioPlot_residual_fit.py

## \ingroup tutorial_hist

## \notebook

## Example which shows how you can get the graph of the lower plot and set the y axis range for it.

##

## Since the lower plot is not created until `TRatioPlot::Draw` is called, you can only use the method

## afterwards.

## Inspired 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")

c1.SetLogy()

h1 = ROOT.TH1D("h1", "h1", 50, -5, 5)

h1.FillRandom("gaus", 2000)

h1.Fit("gaus")

h1.SetMinimum(0.001)

h1.GetXaxis().SetTitle("x")

h1.GetYaxis().SetTitle("y")

rp1 = ROOT.TRatioPlot(h1)

rp1.Draw()

rp1.GetLowerRefGraph().SetMinimum(-2)

rp1.GetLowerRefGraph().SetMaximum(2)

c1.Update()