Changes between Version 7 and Version 8 of WorkBook/Tutorials/Student

Timestamp:

Sep 8, 2019, 1:12:34 PM (5 years ago)

Author:

Michele Selvaggi

Comment:

--

WorkBook/Tutorials/Student

@@ -57 +57 @@
 TFile *f = TFile::Open("data.root");
 TBrowser browser;
-f->Get("Delphes")->Draw("Electron.PT");
+f->Get("Delphes")->Draw("Muon.PT");
 }}}
 
@@ -65 +65 @@
 
 {{{
-f->Get("Delphes")->Draw("Jet.P4().P()");
+f->Get("Delphes")->Draw("Electron.P4().P()");
 f->Get("Delphes")->Draw("Jet.P4().M()");
 }}}
 
+
+In order to perform an event-loop with a more sophisticated event selection you will have to write a small python macro. This macro takes as input the {{{data.root}}} and produce an output file that contains a couple of histograms. Copy paste inside a file called {{{macro.py}}}, and run it via the command {{{python example.py histograms.root}}}.
+The {{{histograms.root}}} file can then be browsed as done before with the data file. 
+
+{{{
+# example event loop macro
+#!/usr/bin/env python
+
+import sys
+import ROOT
+
+if len(sys.argv) < 2:
+  print " Usage: python macro.py data.root histograms.root"
+  sys.exit(1)
+
+ROOT.gSystem.Load("libDelphes")
+
+try:
+  ROOT.gInterpreter.Declare('#include "classes/SortableObject.h"')
+  ROOT.gInterpreter.Declare('#include "classes/DelphesClasses.h"')
+  ROOT.gInterpreter.Declare('#include "external/ExRootAnalysis/ExRootTreeReader.h"')
+except:
+  pass
+
+inputFile = sys.argv[1]
+outputFile = sys.argv[2]
+
+# Create chain of root trees
+chain = ROOT.TChain("Delphes")
+chain.Add(inputFile)
+
+# Create object of class ExRootTreeReader
+treeReader = ROOT.ExRootTreeReader(chain)
+numberOfEntries = treeReader.GetEntries()
+
+# Get pointers to branches used in this analysis
+branchMuon = treeReader.UseBranch("Muon")
+branchJet = treeReader.UseBranch("Jet")
+
+# Book histograms
+histMuonMultiplicity = ROOT.TH1F("histMuonMultiplicity", "M_{recoil} [GeV]", 60, 100.0, 160.0)
+
+ptot = ROOT.TLorentzVector(0.,0.,0.,240.)
+# Loop over all events
+for entry in range(0, numberOfEntries):
+  # Load selected branches with data from specified event
+  treeReader.ReadEntry(entry)
+
+  # If event contains at least 2 muons
+  if branchMuon.GetEntries() > 1:
+
+    mu1 = branchMuon.At(0)
+    mu2 = branchMuon.At(1)
+
+    pll = mu1.P4() + mu2.P4()
+    ph = ptot - pll
+
+    histMass.Fill(ph.M())
+
+out_root = ROOT.TFile(outputFile,"RECREATE")
+histMass.Write()
+}}}