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.ch/files/NanoAOD_DoubleMuon_CMS2011OpenData.root Based on RDataFrame's df102_NanoAODDimuonAnalysis.C

 
// NOTE: The RNTuple classes are experimental at this point.
// Functionality, interface, and data format is still subject to changes.
// Do not use for real data!
 
// Until C++ runtime modules are universally used, we explicitly load the ntuple library.  Otherwise
// triggering autoloading from the use of templated types would require an exhaustive enumeration
// of "all" template instances in the LinkDef file.
R__LOAD_LIBRARY(ROOTNTuple)
 
#include <ROOT/RDataFrame.hxx>
#include <ROOT/RNTuple.hxx>
#include <ROOT/RNTupleDS.hxx>
#include <ROOT/RVec.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>
 
// Import classes from experimental namespace for the time being
using RNTupleReader = ROOT::Experimental::RNTupleReader;
using RNTupleDS = ROOT::Experimental::RNTupleDS;
 
constexpr char const* kNTupleFileName = "http://root.cern.ch/files/tutorials/ntpl004_dimuon_v0.root";
 
 
/// A wrapper for ROOT's InvariantMass function that takes std::vector instead of RVecs
template <typename T>
T InvariantMassStdVector(std::vector<T>& pt, std::vector<T>& eta, std::vector<T>& phi, std::vector<T>& mass)
{
   assert(pt.size() == 2 && eta.size() == 2 && phi.size() == 2 && mass.size() == 2);
 
   // We adopt the memory here, no copy
   ROOT::RVec<float> rvPt(pt);
   ROOT::RVec<float> rvEta(eta);
   ROOT::RVec<float> rvPhi(phi);
   ROOT::RVec<float> rvMass(mass);
 
   return InvariantMass(rvPt, rvEta, rvPhi, rvMass);
}
 
 
void ntpl004_dimuon() {
   // Use all available CPU cores
   ROOT::EnableImplicitMT();
 
   auto df = ROOT::Experimental::MakeNTupleDataFrame("Events", kNTupleFileName);
 
   // The tutorial is identical to df102_NanoAODDimuonAnalysis except the use of
   // InvariantMassStdVector instead of InvariantMass (to be fixed in a later version 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", InvariantMassStdVector<float>, {"Muon_pt", "Muon_eta", "Muon_phi", "Muon_mass"});
   auto df_size = df_os.Define("eta_size", "Muon_mass.size()");
 
   // 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.