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source: git/README@ c5696dd

Last change on this file since c5696dd was 4c9835d, checked in by Pavel Demin <pavel.demin@…>, 4 years ago

update command configuring ROOT and GCC on LXPLUS

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[c2f56f7]1Quick start with Delphes
2========================
3
4Commands to get the code:
5
[69da136]6 wget http://cp3.irmp.ucl.ac.be/downloads/Delphes-3.4.2.tar.gz
[c2f56f7]7
[69da136]8 tar -zxf Delphes-3.4.2.tar.gz
[c2f56f7]9
10Commands to compile the code:
11
[69da136]12 cd Delphes-3.4.2
[c2f56f7]13
14 make
15
16Finally, we can run Delphes:
17
18 ./DelphesHepMC
19
20Command line parameters:
21
22 ./DelphesHepMC config_file output_file [input_file(s)]
23 config_file - configuration file in Tcl format
24 output_file - output file in ROOT format,
25 input_file(s) - input file(s) in HepMC format,
26 with no input_file, or when input_file is -, read standard input.
27
28Let's simulate some Z->ee events:
29
30 wget http://cp3.irmp.ucl.ac.be/downloads/z_ee.hep.gz
31 gunzip z_ee.hep.gz
32 ./DelphesSTDHEP cards/delphes_card_CMS.tcl delphes_output.root z_ee.hep
33
34or
35
36 curl -s http://cp3.irmp.ucl.ac.be/downloads/z_ee.hep.gz | gunzip | ./DelphesSTDHEP cards/delphes_card_CMS.tcl delphes_output.root
37
38For more detailed documentation, please visit
39
40https://cp3.irmp.ucl.ac.be/projects/delphes/wiki/WorkBook
41
42Configure Delphes on lxplus.cern.ch
43====================================
44
45git clone git://github.com/delphes/delphes.git Delphes
46
47cd Delphes
48
[4c9835d]49source /cvmfs/sft.cern.ch/lcg/views/LCG_99/x86_64-centos7-gcc10-opt/setup.sh
[c2f56f7]50
51make
52
53
54Simple analysis using TTree::Draw
55=================================
56
57Now we can start ROOT and look at the data stored in the output ROOT file.
58
59Start ROOT and load Delphes shared library:
60
61 root -l
62 gSystem->Load("libDelphes");
63
64Open ROOT file and do some basic analysis using Draw or TBrowser:
65
[7ce5d1c]66 TFile *f = TFile::Open("delphes_output.root");
67 f->Get("Delphes")->Draw("Electron.PT");
[c2f56f7]68 TBrowser browser;
69
70Note 1: Delphes - tree name, it can be learned e.g. from TBrowser
71
72Note 2: Electron - branch name; PT - variable (leaf) of this branch
73
74Complete description of all branches can be found in
75
76 doc/RootTreeDescription.html
77
78This information is also available at
79
80 https://cp3.irmp.ucl.ac.be/projects/delphes/wiki/WorkBook/RootTreeDescription
81
82Macro-based analysis
83====================
84
85Analysis macro consists of histogram booking, event loop (histogram filling),
86histogram display.
87
88Start ROOT and load Delphes shared library:
89
90 root -l
91 gSystem->Load("libDelphes");
92
93Basic analysis macro:
94
95{
96 // Create chain of root trees
97 TChain chain("Delphes");
98 chain.Add("delphes_output.root");
99
100 // Create object of class ExRootTreeReader
101 ExRootTreeReader *treeReader = new ExRootTreeReader(&chain);
102 Long64_t numberOfEntries = treeReader->GetEntries();
103
104 // Get pointers to branches used in this analysis
105 TClonesArray *branchElectron = treeReader->UseBranch("Electron");
106
107 // Book histograms
108 TH1 *histElectronPT = new TH1F("electron pt", "electron P_{T}", 50, 0.0, 100.0);
109
110 // Loop over all events
111 for(Int_t entry = 0; entry < numberOfEntries; ++entry)
112 {
113
114 // Load selected branches with data from specified event
115 treeReader->ReadEntry(entry);
116
117 // If event contains at least 1 electron
118 if(branchElectron->GetEntries() > 0)
119 {
120 // Take first electron
121 Electron *electron = (Electron*) branchElectron->At(0);
122
123 // Plot electron transverse momentum
124 histElectronPT->Fill(electron->PT);
125
126 // Print electron transverse momentum
127 cout << electron->PT << endl;
128 }
129
130 }
131
132 // Show resulting histograms
133 histElectronPT->Draw();
134}
135
136
137More advanced macro-based analysis
138==================================
139
140The 'examples' directory contains ROOT macros Example1.C, Example2.C and Example3.C.
141
142Here are the commands to run these ROOT macros:
143
144 root -l
145 .X examples/Example1.C("delphes_output.root");
146
147or
148
149 root -l examples/Example1.C'("delphes_output.root")'
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