// @(#)root/hist:$Id: TGraphErrors.cxx 41332 2011-10-11 13:28:08Z couet $
// Author: Rene Brun   15/09/96

/*************************************************************************
 * Copyright (C) 1995-2000, Rene Brun and Fons Rademakers.               *
 * All rights reserved.                                                  *
 *                                                                       *
 * For the licensing terms see $ROOTSYS/LICENSE.                         *
 * For the list of contributors see $ROOTSYS/README/CREDITS.             *
 *************************************************************************/

#include <string.h>

#include "Riostream.h"
#include "TROOT.h"
#include "TGraphErrors.h"
#include "TStyle.h"
#include "TMath.h"
#include "TArrow.h"
#include "TBox.h"
#include "TVirtualPad.h"
#include "TH1.h"
#include "TF1.h"
#include "TVector.h"
#include "TVectorD.h"
#include "TStyle.h"
#include "TClass.h"
#include "TSystem.h"
#include <string>

ClassImp(TGraphErrors)


//______________________________________________________________________________
/* Begin_Html
<center><h2>TGraphErrors class</h2></center>
A TGraphErrors is a TGraph with error bars.
<p>
The TGraphErrors painting is permofed thanks to the
<a href="http://root.cern.ch/root/html/TGraphPainter.html">TGraphPainter</a>
class. All details about the various painting options are given in
<a href="http://root.cern.ch/root/html/TGraphPainter.html">this class</a>.
<p>
The picture below gives an example:
End_Html
Begin_Macro(source)
{
   c1 = new TCanvas("c1","A Simple Graph with error bars",200,10,700,500);
   c1->SetFillColor(42);
   c1->SetGrid();
   c1->GetFrame()->SetFillColor(21);
   c1->GetFrame()->SetBorderSize(12);
   Int_t n = 10;
   Double_t x[n]  = {-0.22, 0.05, 0.25, 0.35, 0.5, 0.61,0.7,0.85,0.89,0.95};
   Double_t y[n]  = {1,2.9,5.6,7.4,9,9.6,8.7,6.3,4.5,1};
   Double_t ex[n] = {.05,.1,.07,.07,.04,.05,.06,.07,.08,.05};
   Double_t ey[n] = {.8,.7,.6,.5,.4,.4,.5,.6,.7,.8};
   gr = new TGraphErrors(n,x,y,ex,ey);
   gr->SetTitle("TGraphErrors Example");
   gr->SetMarkerColor(4);
   gr->SetMarkerStyle(21);
   gr->Draw("ALP");
   return c1;
}
End_Macro */


//______________________________________________________________________________
TGraphErrors::TGraphErrors(): TGraph()
{
   // TGraphErrors default constructor.

   if (!CtorAllocate()) return;
}


//______________________________________________________________________________
TGraphErrors::TGraphErrors(Int_t n)
   : TGraph(n)
{
   // TGraphErrors normal constructor.
   //
   //  the arrays are preset to zero

   if (!CtorAllocate()) return;
   FillZero(0, fNpoints);
}


//______________________________________________________________________________
TGraphErrors::TGraphErrors(Int_t n, const Float_t *x, const Float_t *y, const Float_t *ex, const Float_t *ey)
   : TGraph(n, x, y)
{
   // TGraphErrors normal constructor.
   //
   //  if ex or ey are null, the corresponding arrays are preset to zero

   if (!CtorAllocate()) return;

   for (Int_t i = 0; i < n; i++) {
      if (ex) fEX[i] = ex[i];
      else    fEX[i] = 0;
      if (ey) fEY[i] = ey[i];
      else    fEY[i] = 0;
   }
}


//______________________________________________________________________________
TGraphErrors::TGraphErrors(Int_t n, const Double_t *x, const Double_t *y, const Double_t *ex, const Double_t *ey)
   : TGraph(n, x, y)
{
   // TGraphErrors normal constructor.
   //
   //  if ex or ey are null, the corresponding arrays are preset to zero

   if (!CtorAllocate()) return;

   n = sizeof(Double_t) * fNpoints;
   if (ex) memcpy(fEX, ex, n);
   else    memset(fEX, 0, n);
   if (ey) memcpy(fEY, ey, n);
   else    memset(fEY, 0, n);
}


//______________________________________________________________________________
TGraphErrors::TGraphErrors(const TVectorF &vx, const TVectorF &vy, const TVectorF &vex, const TVectorF &vey)
   : TGraph()
{
   // constructor with four vectors of floats in input
   // A grapherrors is built with the X coordinates taken from vx and Y coord from vy
   // and the errors from vectors vex and vey.
   // The number of points in the graph is the minimum of number of points
   // in vx and vy.

   fNpoints = TMath::Min(vx.GetNrows(), vy.GetNrows());
   if (!TGraph::CtorAllocate()) return;
   if (!CtorAllocate()) return;
   Int_t ivxlow  = vx.GetLwb();
   Int_t ivylow  = vy.GetLwb();
   Int_t ivexlow = vex.GetLwb();
   Int_t iveylow = vey.GetLwb();
   for (Int_t i = 0; i < fNpoints; i++) {
      fX[i]   = vx(i + ivxlow);
      fY[i]   = vy(i + ivylow);
      fEX[i]  = vex(i + ivexlow);
      fEY[i]  = vey(i + iveylow);
   }
}


//______________________________________________________________________________
TGraphErrors::TGraphErrors(const TVectorD  &vx, const TVectorD  &vy, const TVectorD  &vex, const TVectorD  &vey)
   : TGraph()
{
   // constructor with four vectors of doubles in input
   // A grapherrors is built with the X coordinates taken from vx and Y coord from vy
   // and the errors from vectors vex and vey.
   // The number of points in the graph is the minimum of number of points
   // in vx and vy.

   fNpoints = TMath::Min(vx.GetNrows(), vy.GetNrows());
   if (!TGraph::CtorAllocate()) return;
   if (!CtorAllocate()) return;
   Int_t ivxlow  = vx.GetLwb();
   Int_t ivylow  = vy.GetLwb();
   Int_t ivexlow = vex.GetLwb();
   Int_t iveylow = vey.GetLwb();
   for (Int_t i = 0; i < fNpoints; i++) {
      fX[i]   = vx(i + ivxlow);
      fY[i]   = vy(i + ivylow);
      fEX[i]  = vex(i + ivexlow);
      fEY[i]  = vey(i + iveylow);
   }
}


//______________________________________________________________________________
TGraphErrors::TGraphErrors(const TGraphErrors &gr)
   : TGraph(gr)
{
   // TGraphErrors copy constructor

   if (!CtorAllocate()) return;

   Int_t n = sizeof(Double_t) * fNpoints;
   memcpy(fEX, gr.fEX, n);
   memcpy(fEY, gr.fEY, n);
}


//______________________________________________________________________________
TGraphErrors& TGraphErrors::operator=(const TGraphErrors &gr)
{
   // TGraphErrors assignment operator

   if (this != &gr) {
      TGraph::operator=(gr);
      if (!CtorAllocate()) return *this;

      Int_t n = sizeof(Double_t) * fNpoints;
      memcpy(fEX, gr.fEX, n);
      memcpy(fEY, gr.fEY, n);
   }
   return *this;
}


//______________________________________________________________________________
TGraphErrors::TGraphErrors(const TH1 *h)
   : TGraph(h)
{
   // TGraphErrors constructor importing its parameters from the TH1 object passed as argument

   if (!CtorAllocate()) return;

   for (Int_t i = 0; i < fNpoints; i++) {
      fEX[i] = h->GetBinWidth(i + 1) * gStyle->GetErrorX();
      fEY[i] = h->GetBinError(i + 1);
   }
}


//______________________________________________________________________________
TGraphErrors::TGraphErrors(const char *filename, const char *format, Option_t *option)
   : TGraph(100)
{
   // GraphErrors constructor reading input from filename
   // filename is assumed to contain at least 3 columns of numbers
   // convention for format (default="%lg %lg %lg %lg)
   //  format = "%lg %lg"         read only 2 first columns into X,Y
   //  format = "%lg %lg %lg"     read only 3 first columns into X,Y and EY
   //  format = "%lg %lg %lg %lg" read only 4 first columns into X,Y,EX,EY.
   // For files separated by a specific delimiter different from ' ' and '\t' (e.g. ';' in csv files)
   // you can avoid using %*s to bypass this delimiter by explicitly specify the "option" argument,
   // e.g. option=" \t,;" for columns of figures separated by any of these characters (' ', '\t', ',', ';') 
   // used once (e.g. "1;1") or in a combined way (" 1;,;;  1"). 
   // Note in that case, the instanciation is about 2 times slower.

   if (!CtorAllocate()) return;
   Double_t x, y, ex, ey;
   TString fname = filename;
   gSystem->ExpandPathName(fname);
   ifstream infile(fname.Data());
   if (!infile.good()) {
      MakeZombie();
      Error("TGraphErrors", "Cannot open file: %s, TGraphErrors is Zombie", filename);
      fNpoints = 0;
      return;
   }
   std::string line;
   Int_t np = 0;

   if (strcmp(option, "") == 0) { // No delimiters specified (standard constructor).

      Int_t ncol = CalculateScanfFields(format);  //count number of columns in format
      Int_t res;
      while (std::getline(infile, line, '\n')) {
         ex = ey = 0;
         if (ncol < 3) {
            res = sscanf(line.c_str(), format, &x, &y);
         } else if (ncol < 4) {
            res = sscanf(line.c_str(), format, &x, &y, &ey);
         } else {
            res = sscanf(line.c_str(), format, &x, &y, &ex, &ey);
         }
         if (res < 2) {
            continue; //skip empty and ill-formed lines
         }
         SetPoint(np, x, y);
         SetPointError(np, ex, ey);
         np++;
      }
      Set(np);

   } else { // A delimiter has been specified in "option"

      // Checking format and creating its boolean equivalent
      TString format_ = TString(format) ;
      format_.ReplaceAll(" ", "") ;
      format_.ReplaceAll("\t", "") ;
      format_.ReplaceAll("lg", "") ;
      format_.ReplaceAll("s", "") ;
      format_.ReplaceAll("%*", "0") ;
      format_.ReplaceAll("%", "1") ;
      if (!format_.IsDigit()) {
         Error("TGraphErrors", "Incorrect input format! Allowed format tags are {\"%%lg\",\"%%*lg\" or \"%%*s\"}");
         return ;
      }
      Int_t ntokens = format_.Length() ;
      if (ntokens < 2) {
         Error("TGraphErrors", "Incorrect input format! Only %d tag(s) in format whereas at least 2 \"%%lg\" tags are expected!", ntokens);
         return ;
      }
      Int_t ntokensToBeSaved = 0 ;
      Bool_t * isTokenToBeSaved = new Bool_t [ntokens] ;
      for (Int_t idx = 0; idx < ntokens; idx++) {
         isTokenToBeSaved[idx] = TString::Format("%c", format_[idx]).Atoi() ; //atoi(&format_[idx]) does not work for some reason...
         if (isTokenToBeSaved[idx] == 1) {
            ntokensToBeSaved++ ;
         }
      }
      if (ntokens >= 2 && (ntokensToBeSaved < 2 || ntokensToBeSaved > 4)) { //first condition not to repeat the previous error message
         Error("TGraphErrors", "Incorrect input format! There are %d \"%%lg\" tag(s) in format whereas 2,3 or 4 are expected!", ntokensToBeSaved);
         return ;
      }

      // Initializing loop variables
      Bool_t isLineToBeSkipped = kFALSE ; //empty and ill-formed lines
      char * token = NULL ;
      TString token_str = "" ;
      Int_t token_idx = 0 ;
      Double_t * value = new Double_t [4] ; //x,y,ex,ey buffers
      for (Int_t k = 0; k < 4; k++) {
         value[k] = 0. ;
      }
      Int_t value_idx = 0 ;

      // Looping
      while (std::getline(infile, line, '\n')) {
         if (line != "") {
            token = strtok(const_cast<char*>(line.c_str()), option) ;
            while (token != NULL && value_idx < ntokensToBeSaved) {
               if (isTokenToBeSaved[token_idx]) {
                  token_str = TString(token) ;
                  token_str.ReplaceAll("\t", "") ;
                  if (!token_str.IsFloat()) {
                     isLineToBeSkipped = kTRUE ;
                     break ;
                  } else {
                     value[value_idx] = token_str.Atof() ;
                     value_idx++ ;
                  }
               }
               token = strtok(NULL, option) ; //next token
               token_idx++ ;
            }
            if (!isLineToBeSkipped && value_idx > 1) { //i.e. 2,3 or 4
               x = value[0] ;
               y = value[1] ;
               ex = value[2] ;
               ey = value[3] ;
               SetPoint(np, x, y) ;
               SetPointError(np, ex, ey);
               np++ ;
            }
         }
         isLineToBeSkipped = kFALSE ;
         token = NULL ;
         token_idx = 0 ;
         value_idx = 0 ;
      }
      Set(np) ;

      // Cleaning
      delete [] isTokenToBeSaved ;
      delete [] value ;
      delete token ;
   }
   infile.close();
}


//______________________________________________________________________________
TGraphErrors::~TGraphErrors()
{
   // TGraphErrors default destructor.

   delete [] fEX;
   delete [] fEY;
}


//______________________________________________________________________________
void TGraphErrors::Apply(TF1 *f)
{
   // apply function to all the data points
   // y = f(x,y)
   //
   // The error is calculated as ey=(f(x,y+ey)-f(x,y-ey))/2
   // This is the same as error(fy) = df/dy * ey for small errors
   //
   // For generic functions the symmetric errors might become non-symmetric
   // and are averaged here. Use TGraphAsymmErrors if desired.
   //
   // error on x doesn't change
   // function suggested/implemented by Miroslav Helbich <helbich@mail.desy.de>

   Double_t x, y, ex, ey;

   if (fHistogram) {
      delete fHistogram;
      fHistogram = 0;
   }
   for (Int_t i = 0; i < GetN(); i++) {
      GetPoint(i, x, y);
      ex = GetErrorX(i);
      ey = GetErrorY(i);

      SetPoint(i, x, f->Eval(x, y));
      SetPointError(i, ex, TMath::Abs(f->Eval(x, y + ey) - f->Eval(x, y - ey)) / 2.);
   }
   if (gPad) gPad->Modified();
}


//______________________________________________________________________________
Int_t TGraphErrors::CalculateScanfFields(const char *fmt)
{
   // Calculate scan fields.

   Int_t fields = 0;
   while ((fmt = strchr(fmt, '%'))) {
      Bool_t skip = kFALSE;
      while (*(++fmt)) {
         if ('[' == *fmt) {
            if (*++fmt && '^' == *fmt) ++fmt; // "%[^]a]"
            if (*++fmt && ']' == *fmt) ++fmt; // "%[]a]" or "%[^]a]"
            while (*fmt && *fmt != ']')
               ++fmt;
            if (!skip) ++fields;
            break;
         }
         if ('%' == *fmt) break; // %% literal %
         if ('*' == *fmt) {
            skip = kTRUE; // %*d -- skip a number
         } else if (strchr("dDiouxXxfegEscpn", *fmt)) {
            if (!skip) ++fields;
            break;
         }
         // skip modifiers & field width
      }
   }
   return fields;
}


//______________________________________________________________________________
void TGraphErrors::ComputeRange(Double_t &xmin, Double_t &ymin, Double_t &xmax, Double_t &ymax) const
{
   // Compute range.

   TGraph::ComputeRange(xmin, ymin, xmax, ymax);

   for (Int_t i = 0; i < fNpoints; i++) {
      if (fX[i] - fEX[i] < xmin) {
         if (gPad && gPad->GetLogx()) {
            if (fEX[i] < fX[i]) xmin = fX[i] - fEX[i];
            else                xmin = TMath::Min(xmin, fX[i] / 3);
         } else {
            xmin = fX[i] - fEX[i];
         }
      }
      if (fX[i] + fEX[i] > xmax) xmax = fX[i] + fEX[i];
      if (fY[i] - fEY[i] < ymin) {
         if (gPad && gPad->GetLogy()) {
            if (fEY[i] < fY[i]) ymin = fY[i] - fEY[i];
            else                ymin = TMath::Min(ymin, fY[i] / 3);
         } else {
            ymin = fY[i] - fEY[i];
         }
      }
      if (fY[i] + fEY[i] > ymax) ymax = fY[i] + fEY[i];
   }
}


//______________________________________________________________________________
void TGraphErrors::CopyAndRelease(Double_t **newarrays,
                                  Int_t ibegin, Int_t iend, Int_t obegin)
{
   // Copy and release.

   CopyPoints(newarrays, ibegin, iend, obegin);
   if (newarrays) {
      delete[] fX;
      fX = newarrays[2];
      delete[] fY;
      fY = newarrays[3];
      delete[] fEX;
      fEX = newarrays[0];
      delete[] fEY;
      fEY = newarrays[1];
      delete[] newarrays;
   }
}


//______________________________________________________________________________
Bool_t TGraphErrors::CopyPoints(Double_t **arrays, Int_t ibegin, Int_t iend,
                                Int_t obegin)
{
   // Copy errors from fEX and fEY to arrays[0] and arrays[1]
   // or to fX and fY. Copy points.

   if (TGraph::CopyPoints(arrays ? arrays + 2 : 0, ibegin, iend, obegin)) {
      Int_t n = (iend - ibegin) * sizeof(Double_t);
      if (arrays) {
         memmove(&arrays[0][obegin], &fEX[ibegin], n);
         memmove(&arrays[1][obegin], &fEY[ibegin], n);
      } else {
         memmove(&fEX[obegin], &fEX[ibegin], n);
         memmove(&fEY[obegin], &fEY[ibegin], n);
      }
      return kTRUE;
   } else {
      return kFALSE;
   }
}


//______________________________________________________________________________
Bool_t TGraphErrors::CtorAllocate()
{
   // Constructor allocate.

   if (!fNpoints) {
      fEX = fEY = 0;
      return kFALSE;
   } else {
      fEX = new Double_t[fMaxSize];
      fEY = new Double_t[fMaxSize];
   }
   return kTRUE;
}


//______________________________________________________________________________
void TGraphErrors::FillZero(Int_t begin, Int_t end, Bool_t from_ctor)
{
   // Set zero values for point arrays in the range [begin, end]

   if (!from_ctor) {
      TGraph::FillZero(begin, end, from_ctor);
   }
   Int_t n = (end - begin) * sizeof(Double_t);
   memset(fEX + begin, 0, n);
   memset(fEY + begin, 0, n);
}


//______________________________________________________________________________
Double_t TGraphErrors::GetErrorX(Int_t i) const
{
   // This function is called by GraphFitChisquare.
   // It returns the error along X at point i.

   if (i < 0 || i >= fNpoints) return -1;
   if (fEX) return fEX[i];
   return -1;
}


//______________________________________________________________________________
Double_t TGraphErrors::GetErrorY(Int_t i) const
{
   // This function is called by GraphFitChisquare.
   // It returns the error along Y at point i.

   if (i < 0 || i >= fNpoints) return -1;
   if (fEY) return fEY[i];
   return -1;
}


//______________________________________________________________________________
Double_t TGraphErrors::GetErrorXhigh(Int_t i) const
{
   // This function is called by GraphFitChisquare.
   // It returns the error along X at point i.

   if (i < 0 || i >= fNpoints) return -1;
   if (fEX) return fEX[i];
   return -1;
}


//______________________________________________________________________________
Double_t TGraphErrors::GetErrorXlow(Int_t i) const
{
   // This function is called by GraphFitChisquare.
   // It returns the error along X at point i.

   if (i < 0 || i >= fNpoints) return -1;
   if (fEX) return fEX[i];
   return -1;
}


//______________________________________________________________________________
Double_t TGraphErrors::GetErrorYhigh(Int_t i) const
{
   // This function is called by GraphFitChisquare.
   // It returns the error along X at point i.

   if (i < 0 || i >= fNpoints) return -1;
   if (fEY) return fEY[i];
   return -1;
}


//______________________________________________________________________________
Double_t TGraphErrors::GetErrorYlow(Int_t i) const
{
   // This function is called by GraphFitChisquare.
   // It returns the error along X at point i.

   if (i < 0 || i >= fNpoints) return -1;
   if (fEY) return fEY[i];
   return -1;
}


//______________________________________________________________________________
void TGraphErrors::Print(Option_t *) const
{
   // Print graph and errors values.

   for (Int_t i = 0; i < fNpoints; i++) {
      printf("x[%d]=%g, y[%d]=%g, ex[%d]=%g, ey[%d]=%g\n", i, fX[i], i, fY[i], i, fEX[i], i, fEY[i]);
   }
}


//______________________________________________________________________________
void TGraphErrors::SavePrimitive(ostream &out, Option_t *option /*= ""*/)
{
   // Save primitive as a C++ statement(s) on output stream out

   char quote = '"';
   out << "   " << endl;
   if (gROOT->ClassSaved(TGraphErrors::Class())) {
      out << "   ";
   } else {
      out << "   TGraphErrors *";
   }
   out << "gre = new TGraphErrors(" << fNpoints << ");" << endl;
   out << "   gre->SetName(" << quote << GetName() << quote << ");" << endl;
   out << "   gre->SetTitle(" << quote << GetTitle() << quote << ");" << endl;

   SaveFillAttributes(out, "gre", 0, 1001);
   SaveLineAttributes(out, "gre", 1, 1, 1);
   SaveMarkerAttributes(out, "gre", 1, 1, 1);

   for (Int_t i = 0; i < fNpoints; i++) {
      out << "   gre->SetPoint(" << i << "," << fX[i] << "," << fY[i] << ");" << endl;
      out << "   gre->SetPointError(" << i << "," << fEX[i] << "," << fEY[i] << ");" << endl;
   }

   static Int_t frameNumber = 0;
   if (fHistogram) {
      frameNumber++;
      TString hname = fHistogram->GetName();
      hname += frameNumber;
      fHistogram->SetName(Form("Graph_%s", hname.Data()));
      fHistogram->SavePrimitive(out, "nodraw");
      out << "   gre->SetHistogram(" << fHistogram->GetName() << ");" << endl;
      out << "   " << endl;
   }

   // save list of functions
   TIter next(fFunctions);
   TObject *obj;
   while ((obj = next())) {
      obj->SavePrimitive(out, "nodraw");
      if (obj->InheritsFrom("TPaveStats")) {
         out << "   gre->GetListOfFunctions()->Add(ptstats);" << endl;
         out << "   ptstats->SetParent(gre->GetListOfFunctions());" << endl;
      } else {
         out << "   gre->GetListOfFunctions()->Add(" << obj->GetName() << ");" << endl;
      }
   }

   const char *l = strstr(option, "multigraph");
   if (l) {
      out << "   multigraph->Add(gre," << quote << l + 10 << quote << ");" << endl;
   } else {
      out << "   gre->Draw(" << quote << option << quote << ");" << endl;
   }
}


//______________________________________________________________________________
void TGraphErrors::SetPointError(Double_t ex, Double_t ey)
{
   // Set ex and ey values for point pointed by the mouse.

   Int_t px = gPad->GetEventX();
   Int_t py = gPad->GetEventY();

   //localize point to be deleted
   Int_t ipoint = -2;
   Int_t i;
   // start with a small window (in case the mouse is very close to one point)
   for (i = 0; i < fNpoints; i++) {
      Int_t dpx = px - gPad->XtoAbsPixel(gPad->XtoPad(fX[i]));
      Int_t dpy = py - gPad->YtoAbsPixel(gPad->YtoPad(fY[i]));
      if (dpx * dpx + dpy * dpy < 25) {
         ipoint = i;
         break;
      }
   }
   if (ipoint == -2) return;

   fEX[ipoint] = ex;
   fEY[ipoint] = ey;
   gPad->Modified();
}


//______________________________________________________________________________
void TGraphErrors::SetPointError(Int_t i, Double_t ex, Double_t ey)
{
   // Set ex and ey values for point number i.

   if (i < 0) return;
   if (i >= fNpoints) {
      // re-allocate the object
      TGraphErrors::SetPoint(i, 0, 0);
   }
   fEX[i] = ex;
   fEY[i] = ey;
}


//______________________________________________________________________________
void TGraphErrors::Streamer(TBuffer &b)
{
   // Stream an object of class TGraphErrors.

   if (b.IsReading()) {
      UInt_t R__s, R__c;
      Version_t R__v = b.ReadVersion(&R__s, &R__c);
      if (R__v > 2) {
         b.ReadClassBuffer(TGraphErrors::Class(), this, R__v, R__s, R__c);
         return;
      }
      //====process old versions before automatic schema evolution
      TGraph::Streamer(b);
      fEX = new Double_t[fNpoints];
      fEY = new Double_t[fNpoints];
      if (R__v < 2) {
         Float_t *ex = new Float_t[fNpoints];
         Float_t *ey = new Float_t[fNpoints];
         b.ReadFastArray(ex, fNpoints);
         b.ReadFastArray(ey, fNpoints);
         for (Int_t i = 0; i < fNpoints; i++) {
            fEX[i] = ex[i];
            fEY[i] = ey[i];
         }
         delete [] ey;
         delete [] ex;
      } else {
         b.ReadFastArray(fEX, fNpoints);
         b.ReadFastArray(fEY, fNpoints);
      }
      b.CheckByteCount(R__s, R__c, TGraphErrors::IsA());
      //====end of old versions

   } else {
      b.WriteClassBuffer(TGraphErrors::Class(), this);
   }
}


//______________________________________________________________________________
void TGraphErrors::SwapPoints(Int_t pos1, Int_t pos2)
{
   // Swap points

   SwapValues(fEX, pos1, pos2);
   SwapValues(fEY, pos1, pos2);
   TGraph::SwapPoints(pos1, pos2);
}