twoscales.py

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## \file
## \ingroup tutorial_hist
## \notebook
## Example of macro illustrating how to superimpose two histograms
## with different scales in the "same" pad.
## Inspired by work of Rene Brun.
##
## \macro_image
## \macro_code
##
## \author Alberto Ferro
 
#include "TCanvas.h"
#include "TStyle.h"
#include "TH1.h"
#include "TGaxis.h"
#include "TRandom.h"
 
import ROOT
import numpy as np
 
c1 = ROOT.TCanvas("c1","hists with different scales",600,400)
 
ROOT.gStyle.SetOptStat(False)
 
h1 = ROOT.TH1F("h1","my histogram",100,-3,3)
 
h1.Fill(np.array([ROOT.gRandom.Gaus(0, 1) for _ in range(10000)]))
 
h1.Draw()
c1.Update()
 
hint1 = ROOT.TH1F("hint1","h1 bins integral",100,-3,3)
 
sum = 0
for i in range(1,101) :
   sum += h1.GetBinContent(i)
   hint1.SetBinContent(i,sum)
 
rightmax = 1.1*hint1.GetMaximum()
scale = ROOT.gPad.GetUymax()/rightmax
hint1.SetLineColor(ROOT.kRed)
hint1.Scale(scale)
hint1.Draw("same")
 
axis = ROOT.TGaxis(ROOT.gPad.GetUxmax(),ROOT.gPad.GetUymin(),
      ROOT.gPad.GetUxmax(), ROOT.gPad.GetUymax(),0,rightmax,510,"+L")
axis.SetLineColor(ROOT.kRed)
axis.SetLabelColor(ROOT.kRed)
axis.Draw()