Getting Histogram from Tree and adding them after Cuts

Newbie
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1

ROOT Version: 6.18/00
Platform: Ubuntu 20.04
Compiler: Not Provided

Hello experts,

With reference to this Getting the same histograms after cuts I tried the same, but I’m getting a blank histogram plot in a Canvas. I think the solution would be to replace “GOFF” with a “hist” which will give me a plot. But as I wanted to use each histogram for adding in the later case.
Can you please help me sort out my problem?

Also, I would like to add this three histogram (what I want is to add three values e.g. Total_KE = A + B + C, where A,B and C are the kinetic energy of particles). Will I get a correct result if I just add them?

I attached the code and the root file here default_ccqe_Carbon.root (330.4 KB)
E_had.C (1.3 KB)

Thanks in advance.

#include<iostream>
#include<iomanip>
#include<TFile.h>
#include<TTree.h>
#include<TChain.h>
#include<TCanvas.h>
#include<TLegend.h>
#include "TString.h"
#include "TROOT.h"

using namespace std;

void E_had() 
{
   const int nbins = 40;
   const int min   = 0;
   const int max   = 3;
    
   TFile* file_C12 = new TFile("default_ccqe_Carbon.root","OPEN");
   if (!file_C12 || file_C12->IsZombie() ) { delete file_C12; return; }
   
   TTree* t_C12    = (TTree*) file_C12->Get("gst");
   if (! t_C12) { delete file_C12; return;}
   
  
   auto c = new TCanvas();
   c->cd();
   
   TH1D* h_C12_default_KE_nucleon = new TH1D("h_C12_default_KE_nucleon "," ", nbins, min,max);
   TH1D* h_C12_default_pion_plus = new TH1D ("h_C12_default_pion_plus "," ", nbins, min,max);
   TH1D* h_C12_default_pion_0 = new TH1D ("h_C12_default_pion_0 "," ", nbins, min,max);
    
   h_C12_default_KE_nucleon->Sumw2(kTRUE);
 //  t_C12->Draw("(Ef-0.938)>>h_C12_default_KE_nucleon","cc&&pdgf==2212"," goff");
   t_C12->Draw("(Ef-0.13957)>>h_C12_default_pion_plus","cc&&pdgf==211","goff");
   t_C12->Draw("(Ef-0.13498)>>h_C12_default_pion_0","cc&&pdgf==111","goff");

    TString cut_nucleon; 
    cut_nucleon = "cc&&pdgf==2212";
    
    t_C12->Project("h_C12_default_KE_nucleon", "(Ef-0.938)", cut_nucleon);  
    h_C12_default_KE_nucleon->Draw("hist"); 
   c->Update();  
}
2

You should do:

#include<iostream>
#include<iomanip>
#include<TFile.h>
#include<TTree.h>
#include<TChain.h>
#include<TCanvas.h>
#include<TLegend.h>
#include "TString.h"
#include "TROOT.h"

using namespace std;

void E_had()
{
   const int nbins = 40;
   const int min   = 0;
   const int max   = 3;

   TFile* file_C12 = new TFile("default_ccqe_Carbon.root","OPEN");
   if (!file_C12 || file_C12->IsZombie() ) { delete file_C12; return; }

   TTree* t_C12    = (TTree*) file_C12->Get("gst");
   if (! t_C12) { delete file_C12; return;}


   auto c = new TCanvas();
   c->cd();

   TH1D* h_C12_default_KE_nucleon = new TH1D("h_C12_default_KE_nucleon","h_C12_default_KE_nucleon", nbins, min,max);
   TH1D* h_C12_default_pion_plus = new TH1D ("h_C12_default_pion_plus ","h_C12_default_pion_plus", nbins, min,max);
   TH1D* h_C12_default_pion_0 = new TH1D ("h_C12_default_pion_0 ","h_C12_default_pion_0", nbins, min,max);

   h_C12_default_KE_nucleon->Sumw2(kTRUE);
   t_C12->Draw("(Ef-0.938)>>h_C12_default_KE_nucleon","cc&&pdgf==2212"," goff");
   t_C12->Draw("(Ef-0.13957)>>h_C12_default_pion_plus","cc&&pdgf==211","goff");
   t_C12->Draw("(Ef-0.13498)>>h_C12_default_pion_0","cc&&pdgf==111","goff");

    TString cut_nucleon;
    cut_nucleon = "cc&&pdgf==2212";

    t_C12->Project("h_C12_default_KE_nucleon", "(Ef-0.938)", cut_nucleon);

    h_C12_default_KE_nucleon->Draw("hist");

   c->Update();

}

Sorry for the delay.

3

Its okay.
Thanks alot. :slightly_smiling_face: