Example pyROOT script.

example_slac.py

import ROOT
import sys

# Following necessary for loading dictionaries of classes stored in tree could
# also go in .rootlogon.C file
ROOT.gSystem.Load("libEXOUtilities")
def do_analysis(atree):


    c1 = ROOT.TCanvas()
    atree.Draw("fUWires.fChiSquare:fUWires.fRawEnergy") 
    c1.Update()
    raw_input("E")

    # Or get things directly

    for i in range(atree.GetEntries()):
        atree.GetEntry(i)
        ed = atree.EventBranch
        print ed.GetNumChargeClusters()
        break

if __name__ == '__main__':
  
    afile = "/nfs/slac/g/exo_data3/exo_data/data/WIPP/processed/ateam/3560/recon00003560-000.root"
    root_file = ROOT.TFile.Open(afile)
    tree = root_file.Get("tree")
    do_analysis(tree)