From 6cf29f873995a62f7784ba03825669d141076df1 Mon Sep 17 00:00:00 2001
From: Stefan Wunsch <stefan.wunsch@cern.ch>
Date: Thu, 30 Aug 2018 10:53:56 +0200
Subject: [PATCH] [RDF,Tutorial] Add tutorial processing NanoAOD-like file
producing dimuon spectrum from Run2011A CMS OpenData
---
.../dataframe/df102_NanoAODDimuonAnalysis.C | 122 ++++++++++++++++++
1 file changed, 122 insertions(+)
create mode 100644 tutorials/dataframe/df102_NanoAODDimuonAnalysis.C
diff --git a/tutorials/dataframe/df102_NanoAODDimuonAnalysis.C b/tutorials/dataframe/df102_NanoAODDimuonAnalysis.C
new file mode 100644
index 00000000000..14e7ee10b98
--- /dev/null
+++ b/tutorials/dataframe/df102_NanoAODDimuonAnalysis.C
@@ -0,0 +1,122 @@
+/// \file
+/// \ingroup tutorial_dataframe
+/// \notebook -nodraw
+/// This tutorial illustrates how NanoAOD files can be processed with ROOT
+/// dataframes. The NanoAOD-like input file is filled with events from
+/// CMS OpenData containing muon candidates from 2011 data
+/// (DOI: 10.7483/OPENDATA.CMS.RZ34.QR6N). The script matches muon pairs
+/// and produces an histogram of the dimuon mass spectrum showing resonances
+/// up to the Z mass.
+///
+/// \macro_code
+///
+/// \date August 2018
+/// \author Stefan Wunsch
+
+#include "ROOT/RDataFrame.hxx"
+#include "ROOT/RVec.hxx"
+#include "TCanvas.h"
+#include "TH1D.h"
+#include "TLatex.h"
+#include "TLorentzVector.h"
+#include "TStyle.h"
+
+using namespace ROOT::VecOps;
+
+void DrawSpectrum(TH1D& h);
+
+void df102_NanoAODDimuonAnalysis()
+{
+ // Enable implicit multi-threading
+ ROOT::EnableImplicitMT();
+
+ // Create dataframe from NanoAOD file
+ ROOT::RDataFrame df("Events", "NanoAOD_DoubleMuon_CMS2011OpenData.root");
+
+ // Select events with more than two muons
+ auto df_filtered = df.Filter("nMuon>=2", "More than two muons");
+
+ // Find muon pair with highest pt and opposite charge
+ auto find_pair = [](const RVec<float> &pt, const RVec<int> &charge) {
+ // Get indices that sort the muon pts in descending order
+ const auto idx = Reversed(Argsort(pt));
+
+ // Find muon with second-highest pt and opposite charge
+ const auto i1 = idx[0];
+ for (size_t i = 1; i < idx.size(); i++) {
+ const auto i2 = idx[i];
+ if (charge[i1] != charge[i2]) {
+ return RVec<size_t>({i1, i2});
+ }
+ }
+
+ // Return empty selection if no candidate matches
+ return RVec<size_t>({});
+ };
+ auto df_pair = df_filtered.Define("Muon_pair", find_pair, {"Muon_pt", "Muon_charge"})
+ .Filter("Muon_pair.size() == 2", "Found valid pair");
+
+ // Compute invariant mass of the di-muon system
+ auto compute_mass = [](RVec<float> &pt, RVec<float> &eta, RVec<float> &phi,
+ RVec<float> &mass, RVec<size_t> &idx) {
+ // Compose four-vectors of both muons
+ TLorentzVector p1;
+ const auto i1 = idx[0];
+ p1.SetPtEtaPhiM(pt[i1], eta[i1], phi[i1], mass[i1]);
+
+ TLorentzVector p2;
+ const auto i2 = idx[1];
+ p2.SetPtEtaPhiM(pt[i2], eta[i2], phi[i2], mass[i2]);
+
+ // Add four-vectors to build di-muon system and return the invariant mass
+ return (p1 + p2).M();
+ };
+ auto df_mass = df_pair.Define("Dimuon_mass", compute_mass,
+ {"Muon_pt", "Muon_eta", "Muon_phi", "Muon_mass", "Muon_pair"});
+
+ // Plot histogram of di-muon mass spectrum
+ auto h = df_mass.Histo1D({"Dimuon_mass", "Dimuon_mass", 20000, 0.25, 300}, "Dimuon_mass")
+ .GetValue();
+
+ // Draw histogram
+ DrawSpectrum(h);
+}
+
+int main()
+{
+ df102_NanoAODDimuonAnalysis();
+}
+
+void DrawSpectrum(TH1D& h)
+{
+ gStyle->SetOptStat(0);
+ gStyle->SetTextFont(42);
+ TCanvas c("c", "c", 800, 600);
+ c.SetLogx();
+ c.SetLogy();
+
+ h.SetTitle("");
+ h.GetXaxis()->SetTitle("Invariant di-muon mass (GeV)");
+ h.GetXaxis()->SetTitleSize(0.04);
+ h.GetYaxis()->SetTitle("N_{Events}");
+ h.GetYaxis()->SetTitleSize(0.04);
+ h.Draw();
+
+ TLatex label;
+ label.SetNDC(true);
+ label.DrawLatex(0.175, 0.740, "#eta");
+ label.DrawLatex(0.205, 0.785, "#rho,#omega");
+ label.DrawLatex(0.270, 0.750, "#phi");
+ label.DrawLatex(0.400, 0.800, "J/#psi");
+ label.DrawLatex(0.415, 0.680, "#psi'");
+ label.DrawLatex(0.485, 0.760, "Y(1,2,3S)");
+ label.DrawLatex(0.755, 0.620, "Z");
+
+ label.DrawLatex(0.170, 0.350, "#bf{CMS Open Data}");
+ label.DrawLatex(0.170, 0.275, "#bf{#sqrt{s} = 7 TeV}");
+ label.DrawLatex(0.170, 0.200, "#bf{L_{int} = 2.4 fb^{-1}}");
+ label.SetTextSize(0.032);
+ label.DrawLatex(0.10, 0.920, "Run2011A Double Muon Dataset (DOI: 10.7483/OPENDATA.CMS.RZ34.QR6N)");
+
+ c.SaveAs("nanoaod_dimuon_spectrum.pdf");
+}
--
GitLab