ntpl004_dimuon.C File Reference

Detailed Description

Mini-Analysis on CMS OpenData with RDataFrame.

This tutorial illustrates that analyzing data with RDataFrame works the same for both TTree data and RNTuple data. The RNTuple data are converted from the Events tree in http://root.cern/files/NanoAOD_DoubleMuon_CMS2011OpenData.root Based on RDataFrame's df102_NanoAODDimuonAnalysis.C

 
#include <ROOT/RDataFrame.hxx>
 
#include <TCanvas.h>
#include <TH1D.h>
#include <TLatex.h>
#include <TStyle.h>
 
#include <cassert>
#include <cmath>
#include <iostream>
#include <memory>
#include <string>
#include <vector>
#include <utility>
 
constexpr char const *kNTupleFileName = "http://root.cern/files/tutorials/ntpl004_dimuon_v1.root";
 
using namespace ROOT::VecOps;
 
void ntpl004_dimuon() {
   // Use all available CPU cores
   ROOT::EnableImplicitMT();
 
   ROOT::RDataFrame df("Events", kNTupleFileName);
 
   // The tutorial is identical to df102_NanoAODDimuonAnalysis except the use of RNTuple.
 
   // For simplicity, select only events with exactly two muons and require opposite charge
   auto df_2mu = df.Filter("nMuon == 2", "Events with exactly two muons");
   auto df_os = df_2mu.Filter("Muon_charge[0] != Muon_charge[1]", "Muons with opposite charge");
 
   // Compute invariant mass of the dimuon system
   auto df_mass = df_os.Define("Dimuon_mass", InvariantMass<float>, {"Muon_pt", "Muon_eta", "Muon_phi", "Muon_mass"});
 
   // Make histogram of dimuon mass spectrum
   auto h = df_mass.Histo1D({"Dimuon_mass", "Dimuon_mass", 30000, 0.25, 300}, "Dimuon_mass");
 
   // Request cut-flow report
   auto report = df_mass.Report();
 
   // Produce plot
   gStyle->SetOptStat(0); gStyle->SetTextFont(42);
   auto c = new TCanvas("c", "", 800, 700);
   c->SetLogx(); c->SetLogy();
 
   h->SetTitle("");
   h->GetXaxis()->SetTitle("m_{#mu#mu} (GeV)"); h->GetXaxis()->SetTitleSize(0.04);
   h->GetYaxis()->SetTitle("N_{Events}"); h->GetYaxis()->SetTitleSize(0.04);
   h->DrawCopy();
 
   TLatex label; 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
   report->Print();
}

Date

April 2019

Author

The ROOT Team

Definition in file ntpl004_dimuon.C.