//////////////////////////////////////////////////////////
//   This file has been automatically generated 
//     (Mon Mar 19 22:01:33 2018 by ROOT version5.34/10)
//   from TTree save/save
//   found on file: dpalign.root
//
//   For Dark Photon alignment study   03/20/2018  MXL
//
//////////////////////////////////////////////////////////
int ana_align(){
  
//Reset ROOT and connect tree file
   gROOT->Reset();
   TFile *f = (TFile*)gROOT->GetListOfFiles()->FindObject("dpalign.root");
   if (!f) {
      f = new TFile("dpalign.root");
   }
   //   f->GetObject("save",tree);
   TTree * save = (TTree *) gDirectory->Get("save");


   
//Declaration of leaves types
   Int_t           quad;
   Int_t           fElementID;
   Int_t           bElementID;
   Int_t           fElementID_exp;
   Int_t           bElementID_exp;
   Double_t        fPos;
   Double_t        fPos_exp;
   Double_t        bPos;
   Double_t        bPos_exp;
   Double_t        tx;
   Double_t        ty;
   Double_t        x0;
   Double_t        y0;

   // Set branch addresses.
   save->SetBranchAddress("quad",&quad);
   save->SetBranchAddress("fElementID",&fElementID);
   save->SetBranchAddress("bElementID",&bElementID);
   save->SetBranchAddress("fElementID_exp",&fElementID_exp);
   save->SetBranchAddress("bElementID_exp",&bElementID_exp);
   save->SetBranchAddress("fPos",&fPos);
   save->SetBranchAddress("fPos_exp",&fPos_exp);
   save->SetBranchAddress("bPos",&bPos);
   save->SetBranchAddress("bPos_exp",&bPos_exp);
   save->SetBranchAddress("tx",&tx);
   save->SetBranchAddress("ty",&ty);
   save->SetBranchAddress("x0",&x0);
   save->SetBranchAddress("y0",&y0);

   /*
   root [1] save->Show(0)
   ======> EVENT:0
   quad            = 0                   //0, 1, 2, 3 stands for top-left, top-right, bottom-left, bottom-right 
   fElementID      = 9                   //nearest station-1 hit elementID
   bElementID      = 9                   //nearest station-2 hit elementID
   fElementID_exp  = 10                  //expected station-1 hit elementID
   bElementID_exp  = 10                  //expected station-2 hit elementID
   fPos            = -31.3569            // nearest station-1 hit position
   fPos_exp        = -31.6229            // expected station-1 hit position
   bPos            = -29.654              // nearest station-2 hit position
   bPos_exp        = -30.25               // expected station-2 hit position
   tx              = 0.0419373            //track slope in X-Z
   ty              = 0.00957994            //track slope in Y-Z
   x0              = -20.3776              //track intersection in X-Z
   y0              = 9.55376               //track intersection in Y-Z
   */
   
//     This is the loop skeleton
//       To read only selected branches, Insert statements like:
// save->SetBranchStatus("*",0);  // disable all branches
// TTreePlayer->SetBranchStatus("branchname",1);  // activate branchname

//
//--define canvas & histograms 
   // 

   TCanvas * c1 = new TCanvas("c1", "DP Alignment Data", 10, 20, 800, 800);
   TCanvas * c2 = new TCanvas("c2", "DP Alignment Data", 100, 200, 800, 800);
   

   TH1F * qID = new TH1F("qID", "QuadrantID", 10, 0, 5);

   
   Long64_t nentries = save->GetEntries();

   cout << "nentries =" << nentries << endl;
   
   Long64_t nbytes = 0;
   for (Long64_t i=0; i<nentries;i++) {
      nbytes += save->GetEntry(i);

      //      cout << "quad =" << quad << endl;
      qID->Fill(quad);

   } // end of loop


   //-- make plots
   c1->cd();
   c1->Divide(2,2);

   c1->cd(1);
   qID->Draw();

   return nentries;

}