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Reference Guide
df102_NanoAODDimuonAnalysis.py File Reference



Detailed Description

View in nbviewer Open in SWAN Show how NanoAOD files can be processed with RDataFrame.

This tutorial illustrates how NanoAOD files can be processed with ROOT dataframes. The NanoAOD-like input files are filled with 66 mio. events from CMS OpenData containing muon candidates part of 2012 dataset (DOI: 10.7483/OPENDATA.CMS.YLIC.86ZZ and DOI: 10.7483/OPENDATA.CMS.M5AD.Y3V3). The macro matches muon pairs and produces an histogram of the dimuon mass spectrum showing resonances up to the Z mass. Note that the bump at 30 GeV is not a resonance but a trigger effect.

More details about the dataset can be found on the CERN Open Data portal.

import ROOT
# Enable multi-threading
# Create dataframe from NanoAOD files
df = ROOT.RDataFrame("Events", "root://eospublic.cern.ch//eos/opendata/cms/derived-data/AOD2NanoAODOutreachTool/Run2012BC_DoubleMuParked_Muons.root")
# For simplicity, select only events with exactly two muons and require opposite charge
df_2mu = df.Filter("nMuon == 2", "Events with exactly two muons")
df_os = df_2mu.Filter("Muon_charge[0] != Muon_charge[1]", "Muons with opposite charge")
# Compute invariant mass of the dimuon system
df_mass = df_os.Define("Dimuon_mass", "InvariantMass(Muon_pt, Muon_eta, Muon_phi, Muon_mass)")
# Make histogram of dimuon mass spectrum. Note how we can set titles and axis labels in one go.
h = df_mass.Histo1D(("Dimuon_mass", "Dimuon mass;m_{#mu#mu} (GeV);N_{Events}", 30000, 0.25, 300), "Dimuon_mass")
# Request cut-flow report
report = df_mass.Report()
# Produce plot
ROOT.gStyle.SetOptStat(0); ROOT.gStyle.SetTextFont(42)
c = ROOT.TCanvas("c", "", 800, 700)
c.SetLogx(); c.SetLogy()
label = ROOT.TLatex(); label.SetNDC(True)
label.DrawLatex(0.175, 0.740, "#eta")
label.DrawLatex(0.205, 0.775, "#rho,#omega")
label.DrawLatex(0.270, 0.740, "#phi")
label.DrawLatex(0.400, 0.800, "J/#psi")
label.DrawLatex(0.415, 0.670, "#psi'")
label.DrawLatex(0.485, 0.700, "Y(1,2,3S)")
label.DrawLatex(0.755, 0.680, "Z")
label.SetTextSize(0.040); label.DrawLatex(0.100, 0.920, "#bf{CMS Open Data}")
label.SetTextSize(0.030); label.DrawLatex(0.630, 0.920, "#sqrt{s} = 8 TeV, L_{int} = 11.6 fb^{-1}")
# Print cut-flow report
Events with exactly two muons: pass=31104343 all=61540413 -- eff=50.54 % cumulative eff=50.54 %
Muons with opposite charge: pass=24067843 all=31104343 -- eff=77.38 % cumulative eff=39.11 %
April 2019
Stefan Wunsch (KIT, CERN)

Definition in file df102_NanoAODDimuonAnalysis.py.

ROOT's RDataFrame offers a high level interface for analyses of data stored in TTree,...
Definition: RDataFrame.hxx:42