#include <stdio.h>
#include <iostream>
#include <fstream>
#include <vector>
#include <iomanip>

#include "TNtuple.h"
#include "TFile.h"
#include "TH1F.h"
#include "TH2F.h"
#include "TH3F.h"
#include "TTree.h"
#include "TChain.h"
#include "TCanvas.h"
#include "TGraph.h"
#include "TGraphErrors.h"
#include "TF1.h"
#include "TStyle.h"
#include "TCut.h"
#include "TGaxis.h"
#include "TVector.h"
#include "TPaveText.h"
#include "TEllipse.h"
#include "TROOT.h"
#include "TObjArray.h"
#include "TObject.h"
#include "TRandom.h"
#include "TMath.h"

void Study(bool write=false){


  // Global Variables
  float  cut1=2.5;

  // File output
  TFile *f2 = new TFile("plots.root","RECREATE");
  f2->cd();
  
  gRandom->Gaus(2.,4.5);
  
  // histograms and other variables
  TObjArray *array_z_x2y2 = new TObjArray() ;
  TH2D *h_z_x2y2 = new TH2D("h_z_x2y2","h_z_x2y2",500,0,4.0,500,0,4.0);
  
  //Loop on etries and fill week by week
   for(int i=0;i<3e5;i++){

     if( (gRandom->Gaus(0,4.5) ) < cut1 ) {
      h_z_x2y2->Fill(gRandom->Gaus(0,4.5),gRandom->Gaus(0,4.5));  
    }
    
     if(  (h_z_x2y2->GetEntries()>25000)  ){
      array_z_x2y2->AddLast( h_z_x2y2 );
      cout << "before:" << h_z_x2y2->GetEntries() << endl;
      h_z_x2y2->Reset();
      cout << "after:" << h_z_x2y2->GetEntries() << endl;
      cout << "size array_z_x2y2:" << array_z_x2y2->GetEntriesFast() << endl;
    }

   }

   array_z_x2y2->AddLast( h_z_x2y2 );

   f2->cd();
   
   if(write)array_z_x2y2->Write("array_z_x2y2",TObject::kSingleKey);

   TCanvas *c_array_z_x2y2 = new TCanvas("array_z_x2y2","array_z_x2y2",800,800);
   c_array_z_x2y2->SetFillColor(10);
   c_array_z_x2y2->Divide(3,3);
   for(int j=1;j<10;j++){
     if(j>array_z_x2y2->GetEntriesFast()) break;
     c_array_z_x2y2->cd(j);
     array_z_x2y2->At(j-1)->Draw("COLZ");
     TH2D *loc_histo = (TH2D *)array_z_x2y2->At(j-1);
     cout << j << " size:" << loc_histo->GetEntries() << endl;
     c_array_z_x2y2->Update();
   }
   c_array_z_x2y2->Update();
   
}