How to use Root:

http://root.cern.ch/

"How to" page:
http://root.cern.ch/drupal/content/howtos
User's guide:
http://root.cern.ch/drupal/content/users-guide
Reference guide:
http://root.cern.ch/drupal/content/reference-guide

Run it:
root -l

Open a file:
TFile *_file0 = TFile::Open("..... .root")

File browser:
TBrowser <name>

List the directories:
.ls
<directory name>.cd()

Print the tree:
ntuple.Print()

Scan the tree:
ntuple.Scan("<name of a Branch>.<name of a leaf>")

Make a new histogram:
TH1F *name_of_the_histogram = new TH1F("name","title",<#ofXaxis>,<#ofYaxis>,<#ofBins>);

Make a new canvas:
TCanvas *c1=new TCanvas ("name","title",1);

Draw a histogram:
<name of the tree in the file>.Draw("<name of a Branch>.<name of a leaf>")
2D histogram:
<name of the tree in the file>.Draw("<name of a Branch1>.<name of a leaf1>:<name of a Branch2>.<name of a leaf2>")
histogram with cut criteria:
<name of the tree in the file>.Draw("<name of a Branch1>.<name of a leaf1>,<name of a Branch2>.<name of a leaf2><cut criteria>
draw two histogram in one canvas:
<name of the tree in the file>.Draw("<name of a Branch1>.<name of a leaf1>")
<name of the tree in the file>.Draw("<name of a Branch2>.<name of a leaf2>","","SAME")
e.g.:
tree.Draw("pelectron_1.tight:pelectron_1.loose","pelectron_1.tight>-1")

Open an AOD file in root:
gSystem->Load("libFWCoreFWLite");
AutoLibraryLoader::enable();
TFile *_file0 = TFile::Open("rfio:/castor/cern.ch/user/........ .root")
TBrowser b

TChain:
Chain.C:
#include <TChain.h>
void Chain(){
TChain tree("stopAnaMod/tree");
tree.AddFile("stopAnaNtuple_noselection_Chowder_00.root");
tree.Draw("event");
}

Save a histogram to .eps:
TCanvas *c1=new TCanvas ("name","title",1);
<name of the tree in the file>.Draw("<name of a Branch>.<name of a leaf>");
c1->SaveAs("name.eps");

Usage of MakeClass:


This topic: Main > TWikiUsers > AnitaKapusi > HUSUSYRoot
Topic revision: r1 - 2009-06-23 - AnitaKapusi
 
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