import ROOT import sys from DataFormats.FWLite import Events, Handle

# Make VarParsing object # https://twiki.cern.ch/twiki/bin/view/CMS/SWGuideAboutPythonConfigFile#VarParsing_Example from VarParsing import VarParsing options = VarParsing ('python') options.parseArguments()

# Events takes either # - single file name # - list of file names # - VarParsing options

# use Varparsing object events = Events (options)

# create handle outside of loop handle = Handle ("std::vector<pat::Muon>")

# for now, label is just a tuple of strings that is initialized just # like and edm::InputTag label = ("selectedLayer1Muons")

# Create histograms, etc. ROOT.gROOT.SetBatch() # don't pop up canvases ROOT.gROOT.SetStyle('Plain') # white background zmassHist = TH1F ("zmass", "Z Candidate Mass", 50, 20, 220)

# loop over events for event in events: # use getByLabel, just like in cmsRun event.getByLabel (label, handle) # get the product muons = handle.product() # use muons to make Z peak numMuons = len (muons) if muons < 2: continue for outer in xrange (numMuons - 1): outerMuon = muons[outer] for inner in xrange (outer + 1, numMuons): innerMuon = muons[inner] if outerMuon.charge() * innerMuon.charge() >= 0: continue inner4v = TLorentzVector (innerMuon.px(), innerMuon.py(), innerMuon.pz(), innerMuon.energy()) outer4v = TLorentzVector (outerMuon.px(), outerMuon.py(), outerMuon.pz(), outerMuon.energy()) zmassHist.Fill( (inner4v + outer4v).M() )

# make a canvas, draw, and save it c1 = ROOT.TCanvas() zmassHist.Draw() c1.Print ("zmass_py.png") -- AhmedHamedAliHammad - 2015-09-29