Hi
I have a simple pyRoot code that read a json and fills two THStack histos. However, the canvas is still empty . Any ideas?
import ROOT
import json
from ROOT import gROOT, TCanvas, TFile, TGraphErrors, TMath, SetOwnership, TColor, kYellow, kGreen, kWhite, kMagenta, kCyan, kBlue, kOrange, kTeal
import math, sys, optparse, array, time, copy
ROOT.gROOT.SetBatch(ROOT.kTRUE)
# Load the JSON data from file
with open('my_file.json', 'r') as f:
data = json.load(f)
canvas = ROOT.TCanvas('canvas', 'canvas', 200, 100)
# Create a legend
legend = ROOT.TLegend(0.7, 0.7, 0.9, 0.9)
# Create a list of colors
#colors = {'qcd': ROOT.kRed, 'top': ROOT.kGreen, 'ew': ROOT.kBlue, 'ewk': ROOT.kOrange}
colors = {'dy':kYellow, 'qcd':kMagenta, 'qcdpt':kMagenta, 'top':kBlue, 'ew':kGreen+2, 'ewk':kCyan, 'ewknlo':kCyan+1, 'ewknlo61':kCyan+1, 'ewkincl':kTeal, 'ewkincl61':kTeal-4}
canvas = ROOT.TCanvas('canvas', 'canvas')
stacks=[]
for i, entry in enumerate(data):
# Create THStack
label = entry['selection']
stack = ROOT.THStack('stack_{0:s}'.format(label), '')
# Set x-axis label
#stack.GetXaxis().SetTitle(label)
# Loop over each key in the entry
for key, value in entry.items():
if key == 'selection':
continue
# Create histogram and fill with color based on key
hist = ROOT.TH1F(key, '', 100, 0, 1)
hist.SetFillColor(colors[key])
hist.Fill(value)
if i==0 :
legend.AddEntry(hist, key, 'l')
# Add histogram to THStack
stack.Add(hist)
# Add THStack to list of stacks
stacks.append(stack)
# Draw first THStack and set y-axis range
canvas.cd()
legend.Draw()
stacks[0].Draw('hist')
stacks[0].SetMaximum(10**8)
# Loop over remaining THStacks and draw them on top of each other
for stack in stacks[1:]:
stack.Draw('hist same')
canvas.Update()
# Save canvas as PDF
canvas.SaveAs('output.pdf')
