#!/usr/bin/env python
# Based on P.Onyisi example
import sys,os,string
if len(sys.argv)<2:
    print "Usage: python test.py file.root"
    print "Exit.."
    sys.exit()
from ROOT import *
TH1D.SetDefaultSumw2()
gSystem.Load('libDelphes.so')

f=TFile(sys.argv[1])
t=f.Delphes # extract the tree
h=TH1D('ele','Electron #eta',8,-4,4) # initialize a histogram
c1=TCanvas() # build a canvas

n=0
for e in t:   # loop over all events
  if n%100==0: print "Event=",n
  n=n+1
  for electron in e.Electron: # loop over all electrons
     h.Fill(electron.Eta)
h.Draw()
c1.Print('electron.pdf')
if (raw_input("Press any key to exit") != "-9999"):
    c1.Close(); sys.exit(1);