Transvers distribution fpdg=21

[lm17n000032]

Hello ROOTers;

I tried to build a program that make a chain from this two root files tree.root (11.3 KB) tree2.root (20.1 KB)
and then build a histogram entries vs pt for a specific particle pdg=21. I made this:

{

		TFile hfile("hfile.root","recreate"); //create a root file

		TChain ch("tree");	//create a chain of tree

		TCanvas c1("c1","pt distribution pdg 21",700,500);	//create a canvas 700x500 

		ch.Add("tree.root");	//add tree to chain
		ch.Add("tree2.root");


		// devo creare un istogramma e riempirlo con quelle variabili
		TH1F h("h","pt distribution pdg 21",100,0,8);

		//now i need to creare a for in order to fill h 
		//and choose right particle fpdg="21"

		h.GetXaxis().SetTitle("P_t [MeV]");	//set axis names
		h.GetYaxis().SetTitle("Entries");
		h.SetTitle("pt distribution pdg 21");
		h.Draw("((fPx*fPx)+(fPy*fPy))^0.5");	//draw pt
		hfile.Write();	//write on root file
		hfile.Close();	//close root file
}

How can I make a for cycle and fill my h with the variable ((fPxfPx)+(fPyfPy))^0.5 ? And how can i choose the particle?

Thanks for all!

_ROOT Version: 6.18
_Platform: Xubuntu 19.04
_Compiler: gcc version 7.3.0

[Wile_E_Coyote]

{
  TChain ch("tree");
  ch.Add("tree.root");
  ch.Add("tree2.root");
  
  TH1F h("h", "pt distribution pdg 21;P_{t} [MeV];Entries", 100, 0., 8.);
  h.SetDirectory(gROOT); // just a precaution
  
  ch.Project("h", "pow((fPx*fPx)+(fPy*fPy), 0.5)", "fPdgCode == 21");
  
  h.DrawCopy();
  
  TFile hfile("hfile.root", "recreate");
  // hfile.cd(); // just a precaution
  h.Write();
  hfile.Close();
}

[lm17n000032]

@Wile_E_Coyote

ch.Project(“h”, “pow((fPxfPx)+(fPyfPy), 0.5)”, “fPdgCode == 21”);

Can you explain this?

Can i do in a similar way with for? I tried this:

Float_t fPx,fPy;
  		ch.SetBranchAddress("fPx",&fPx);	//set branch address
  		ch.SetBranchAddress("fPy",&fPy);
  		
  		for(Int_t i=0; i<=ch.GetEntries(); i++){
    	
    	//h.Fill(); ???
  											   

If it is possible, how can i fill h and how can i put the condition for fpdg code? I ask only for improve my skills. Thanks for the fast reply.

[Wile_E_Coyote]

TTree::Project

TTree::Draw

Header files for Trees

“Most recent” documentation about how to generate and use an “analysis skeleton”: TTree::MakeClass (see also “ROOT User’s Guide” → “Trees” → “Using TTree::MakeClass”) TTree::MakeSelector (see also “ROOT Primer” → “File I/O and Parallel Analysis” → “N-tuples in ROOT” → “For the advanced user: Processing trees with a selector script” and “ROOT User’s Guide” → “Trees” → “Using TTree::MakeSelector” and “ROOT User’s Guide” → “Example Analysis”) TTree::MakeProxy ROOT::RDataFrame (uses the T…

[lm17n000032]

@lm17n000032

Can i do in a similar way with for? I tried this:

Float_t fPx,fPy;
  		ch.SetBranchAddress("fPx",&fPx);	//set branch address
  		ch.SetBranchAddress("fPy",&fPy);
  		
  		for(Int_t i=0; i<=ch.GetEntries(); i++){
    	
    	//h.Fill(); ???
  						

And what about this? Is it possible to fill ? How can I insert the option for pdg code into for cycle?