//____________________________________________________________________
//
// $Id: makeVarBinSpectra.C,v 1.2 2003/09/23 10:27:21 zbyin Exp $
// $Author: zbyin $
// $Date: 2003/09/23 10:27:21 $
// $Copyright: (C) 2003 BRAHMS Collaboration <brahmlib@rhic.bnl.gov>
//

void makeVarBinSpectra(TString fileName, 
		       TString histoName = "spectraSum1D")
{
  //Build for MRS at the moment. But should work for FS as well.
  //Convert a fixed bin size histogram to a variable bin size histogram
  //Remove the first non-zero bin and last non-zero bin
  
  TDirectory* saveDir = gDirectory;

  TFile *inFile = TFile::Open(fileName.Data());
  TH1F* hOld = 0;
  if (inFile || inFile->IsOpen()) {
    TH1F * hTemp = (TH1F*) inFile->Get(histoName.Data());
    if(!hTemp){
      cout<<"No histogram " << histoName.Data() << " in file " 
	  <<fileName.Data()<<endl;
      return;
    }
    hOld = (TH1F*) hTemp->Clone();
    hOld->SetDirectory(0);
    inFile->Close();
    delete inFile;
  }

  if (!hOld) { 
    Error("makeVarBinSpectra", "Could not access input histogram hOld");
    return;
  }
 
  saveDir->cd();
 
  //Define an output file
  TString dir = GetDir(fileName);
  TString inFileName = GetFileName(fileName);
 
  Char_t outFileName[256];
  sprintf(outFileName, "%s/Niced_%s", dir.Data(), inFileName.Data() );
 
  TFile *outFile = new  TFile(outFileName, "RECREATE");

  Int_t i, j;

  //Define a new variable histogram
  Float_t binEdge[] = {0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9,
		       1.0, 1.2, 1.4, 1.6, 1.9, 2.2, 2.5, 3.0, 3.5, 4.,
		       5., 6.};
  Int_t nBinsNew = sizeof(binEdge)/sizeof(Float_t) - 1;  // NB nbins-1
  Int_t nBinsOld = hOld->GetXaxis()->GetNbins();
  
  TH1F * hNew = new TH1F("VarBinSpectra", 
			 "", nBinsNew, binEdge);
  hNew->SetTitle(hOld->GetTitle());
  hNew->SetStats(kFALSE);
  hNew->GetXaxis()->SetTitle(hOld->GetXaxis()->GetTitle());
  hNew->GetYaxis()->SetTitle(hOld->GetYaxis()->GetTitle());
  hNew->GetXaxis()->SetRangeUser(0.0, 6.0);
  hNew->SetMinimum(1.e-7);
  hNew->SetMaximum(1000);
  hNew->SetTitleOffset(1.3, "Y");
  hNew->SetTitleSize(0.03, "Y");
  hNew->SetLabelSize(0.03, "Y");
  hNew->SetLabelOffset(0.002, "Y");


  Double_t * err = new Double_t[nBinsNew];
  Int_t * binScale = new Int_t[nBinsNew];

  for(i = 0; i <= nBinsNew; i++) {
    err[i] = 0;
    binScale[i] = 0;
  }  

  for(i = 0; i <= nBinsOld; i++){
    Double_t binCenter = hOld->GetXaxis()->GetBinCenter(i);
    Double_t errOld = hOld->GetBinError(i)*binCenter;
    j = hNew->Fill(binCenter, 
		   hOld->GetBinContent(i)*binCenter);
    err[j] += errOld * errOld * binCenter * binCenter;
    binScale[j] ++;
  } //loop over the old histogram 

  for(i = 0; i <= nBinsNew; i++) {
    Double_t newBinCenter = hNew->GetXaxis()->GetBinCenter(i);
    if(binScale[i] != 0) {
      hNew->SetBinContent(i, hNew->GetBinContent(i)/binScale[i]/newBinCenter);
      hNew->SetBinError(i, TMath::Sqrt(err[i])/binScale[i]/newBinCenter);
    }
  }

  //Remove the first non-zero bin
  for(i = 0; i <= nBinsNew; i++){
    if(hNew->GetBinContent(i) != 0.) {
      hNew->SetBinContent(i, 0.);
      hNew->SetBinError(i, 0.);
      break;
    }
  }

  //Remove the last non-zero bin
  for(i = nBinsNew; i >0 ; i--){
    if(hNew->GetBinContent(i) != 0.){
      hNew->SetBinContent(i, 0.);
      hNew->SetBinError(i, 0.);
      break;
    }
  }

  outFile->cd();
  hNew->Write();
  delete [] err;
  delete [] binScale;
  outFile->Close(); 
  delete outFile;
//   delete hOld;

}

TString GetDir(TString base)
{
 
  Int_t size = base.Sizeof()-2;
  Int_t slash = 0;
  for (Int_t idx = size; idx >= 0; idx--)
    if (base.Data()[idx] == '/') {
      slash = idx;
      break;
    }
 
  if (slash) {
    base.Remove(slash);
    return base;
  }
 
  return TString(".");
}

TString GetFileName(TString base){

  Int_t size = base.Sizeof()-2;
  Int_t slash = 0;
  for (Int_t idx = size; idx >= 0; idx--)
    if (base.Data()[idx] == '/') {
      slash = idx;
      break;
    }
 
  if (slash)
    base.Remove(0, slash + 1);
  
  return base;

}

//_________________________________________________
//
// $Log: makeVarBinSpectra.C,v $
// Revision 1.2  2003/09/23 10:27:21  zbyin
// Add logs
//