TreeTest.C

void TreeEnergyWrite(){


  int Ecol1;
  double Ecol2,Ecol3,Ecol4;
  string line_E;
   
  
  TFile* Efile = new TFile("Energy_table.root","recreate");
  TTree* ETree = new TTree("ETree","Energy tree");

  ETree->Branch("Ecol1",&Ecol1,"Ecol1/I"); // ECol1 = Energy values = {200,300.....14000}
  ETree->Branch("Ecol4",&Ecol4,"Ecol4/D"); // Voltage values 

  std::ifstream Energy_file("Energy_table.dat");
  if(Energy_file.is_open()){
    while(getline(Energy_file,line_E)){
      istringstream ssE(line_E);
      ssE >> Ecol1 >> Ecol2 >> Ecol3 >> Ecol4;
      ETree->Fill();
    }
  }

  ETree->Write();
  Efile->Close();
  
}

void TreeTPWrite(){
 
  int energy, col, row, pc;
  double voltage,tot, tot_var, toa, toa_var, time_ref,toa_cut,mean,RMS;
  string line_TP;

  TFile* Efile = new TFile("Energy_table.root");
  TTree* ETree = (TTree*)Efile->Get("ETree");
  ETree->SetBranchAddress("Ecol1",&energy);
  ETree->SetBranchAddress("Ecol4",&voltage);

  
  TFile* TPfile = new TFile("TP.root","update");  
  TTree* TPtree = new TTree("TPtree"," TP tree");
  TPtree->Branch("col",&col,"col/I");
  TPtree->Branch("row",&row,"row/I");
  TPtree->Branch("pc",&pc,"pc/I");
  TPtree->Branch("tot",&tot,"tot/D");
  TPtree->Branch("tot_var",&tot_var,"tot_var/D");
  TPtree->Branch("toa",&toa,"toa/D");
  TPtree->Branch("toa_var",&toa_var,"toa_var/D");
  TPtree->Branch("time_ref",&time_ref,"time_ref/D");
  auto voltageBranch = TPtree->Branch("voltage",&voltage,"voltage/D");// make a new branch and connect it to the same variable as the branch address of the energy tree
  auto Branch_toacut = TPtree->Branch("toa_cut",&toa_cut,"toa_cut/D");

  for(int i = 0; i < ETree->GetEntries(); i++){
    ETree->GetEntry(i);
    // std:: cout << energy << " " << voltage << std::endl;
    std::string TPfilename = "tp_dat_" + std::to_string(energy) + ".dat";
    //std:: cout << " The TPfilenames are : " <<  TPfilename.c_str() <<std::endl;
    std::ifstream TPdatafile(TPfilename.c_str());

    voltageBranch->Fill();
    
    if(TPdatafile.is_open()){

      std::cout << " The data file " << TPfilename.c_str() << " is opened ..." <<std::endl;

      
      // reading through individial tp_dat_ files

      while(getline(TPdatafile,line_TP)){
	  if(line_TP.rfind("#", 0) == 0) {
	    continue;
	  }

	  istringstream ssTP(line_TP);
	  ssTP >> col >> row >> pc >> tot >> tot_var >> toa >> toa_var >> time_ref;
	  TPtree->Fill();
      } //While loop getline
    }//if statement TPdatafile open

    TPtree->Draw("toa",Form("voltage==(%f)",voltage),"goff");
    mean = TMath::Mean(TPtree->GetSelectedRows(), TPtree->GetV1());
    RMS = TMath::RMS(TPtree->GetSelectedRows(), TPtree->GetV1());
    // std::cout <<" mean " << mean << " RMS " << RMS <<std::endl;

    /* for (int isigma=0; isigma < 15; isigma++){
      std::cout << " cut at " << isigma << " times the RMS leaves : " 
      << 100.0*TPtree->GetEntries(Form("toa<(%f) && voltage==(%f)",mean+isigma*RMS,voltage))/TPtree->GetEntries(Form("voltage==(%f)",voltage)) 
      << " percentage of entries " << std::endl;
      }*/

    toa_cut = mean + 6*RMS;
    Branch_toacut->Fill();
    
  }//For loop GetEntries

  //Save only the new version of the tree 

  TPtree->Write("",TObject::kOverwrite);
  
  TPfile->Close();
}


void timewalkfit(){


  // gROOT->Reset();
  
  int col, row, pc ;
  double tot, tot_var, toa, toa_var;

  TFile* TPfile = new TFile("TP.root");
  TTree* TPtree = (TTree*)TPfile->Get("TPtree");
  TPtree->SetBranchAddress("col",&col);
  TPtree->SetBranchAddress("row",&row);
  TPtree->SetBranchAddress("pc",&pc);
  TPtree->SetBranchAddress("tot",&tot);
  TPtree->SetBranchAddress("tot_var",&tot_var);
  TPtree->SetBranchAddress("toa",&toa);
  TPtree->SetBranchAddress("toa_var",&toa_var);


  for(int icol = 0; icol < 256; icol++){
    for (int irow = 0; irow <256; irow++){

      std::cout <<icol << " " << irow << std::endl;

      auto N = TPtree->Draw("voltage:toa:sqrt(toa_var)",Form("col==(%i) && row==(%i) && toa>0 && toa<toa_cut", icol, irow),"goff");
      // cout << N <<std::endl;
      TGraphErrors *graph = new TGraphErrors(N,TPtree->GetV1(),TPtree->GetV2(),0,TPtree->GetV3());

      // std::cout << icol << " " << irow << std::endl; //Correct values printed here..but text file still prints 255_255
    
      auto fitmin = TMath::MinElement(graph->GetN(),graph->GetX());
      // std::cout << "fitmin" << fitmin << std::endl;
    
      auto fitmax = TMath::MaxElement(graph->GetN(),graph->GetX());
      // std::cout << "fitmax " << fitmax << std::endl;
    
      TF1 *fitfuncTOA = new TF1("fitfuncTOA","(([2]/(x-[0]))+ [1])",fitmin,fitmax);
      fitfuncTOA->SetParNames("asymtote","offset","curvature");
    
      int iymax=TMath::LocMax(graph->GetN(),graph->GetY());
      // cout << "iymax " << iymax << std::endl;
      auto ttoa = graph->GetPointX(iymax);
      // cout << "ttoa" << " " << ttoa << std::endl;;
      fitfuncTOA->SetParameter(0,ttoa);
    
      auto xmax = TMath::MaxElement(graph->GetN(),graph->GetX());
      auto dtoa = graph->Eval(xmax);
      // cout << "dtoa" << " " << dtoa <<std::endl;
      fitfuncTOA->SetParameter(1,dtoa);
    
      auto testx = 0.5*fitmax;
      auto ctoa_y = graph->Eval(testx);
      auto ctoa = (ctoa_y - dtoa)*(testx - ttoa);
      // cout << "ctoa" << " " << ctoa <<std::endl;
      fitfuncTOA->SetParameter(2,ctoa);
      
      // gStyle->SetOptFit(1111);
      // fitfuncTOA->SetLineColor(kRed);
      graph->Fit(fitfuncTOA,"R");
      /* graph->GetXaxis()->SetTitle("Volatge[mV]");
	 graph->GetYaxis()->SetTitle ("time difference[ns]");
	 graph->SetTitle(" ");
	 graph->SetMarkerStyle(7);*/
      // graph->Draw("AP");
    
      std::ofstream fitpars;
      fitpars.open("fit_parameters.txt",std::ofstream::app);
      fitpars << icol << "\t" << irow << "\t"  << fitfuncTOA->GetParameter(2)
	      << setw(10) << fitfuncTOA->GetParameter(0) << setw(10) << fitfuncTOA->GetParameter(1) << std::endl; //NO chi2/ndf for the time-being!
      
    }
  }

  TPfile->Close();
}

void TreeTest(){ 

  TreeEnergyWrite();
  TreeTPWrite();
  timewalkfit();

}