TH1K.cxx

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// @(#)root/hist:$Id: TH1K.cxx 35245 2010-09-13 14:03:43Z brun $
// Author: Victor Perevoztchikov <perev@bnl.gov>  21/02/2001

/*************************************************************************
 * 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 <stdlib.h>

#include "Riostream.h"
#include "TH1K.h"
#include "TMath.h"

//______________________________________________________________________________
// The TH1K Class
//
//  TH1K class supports the nearest K Neighbours method,
//       widely used in cluster analysis.
//       This method is especially useful for small statistics.
//
//       In this method :
//         DensityOfProbability ~ 1/DistanceToNearestKthNeighbour
//
//      Ctr TH1K::TH1K(name,title,nbins,xlow,xup,K=0)
//      differs from TH1F only by "K"
//      K - is the order of K Neighbours method, usually >=3
//      K = 0, means default, where K is selected by TH1K in such a way
//             that DistanceToNearestKthNeighbour > BinWidth and K >=3
//
//  This class has been implemented by Victor Perevoztchikov <perev@bnl.gov>

ClassImp(TH1K)


//______________________________________________________________________________
TH1K::TH1K(): TH1(), TArrayF()
{
   // Constructor.

   fDimension = 1;
   fNIn   = 0;
   fReady = 0;
   fKOrd  = 3;
   fKCur  = 0;
}


//______________________________________________________________________________
TH1K::TH1K(const char *name,const char *title,Int_t nbins,Double_t xlow,Double_t xup,Int_t k)
     : TH1(name,title,nbins,xlow,xup), TArrayF(100)
{
   // Create a 1-Dim histogram with fix bins of type float
   // (see TH1K::TH1 for explanation of parameters)

   fDimension = 1;
   fNIn   = 0;
   fReady = 0;
   fKOrd  = k;
   fKCur  = 0;
}


//______________________________________________________________________________
TH1K::~TH1K()
{
   // Destructor.
}


//______________________________________________________________________________
Int_t TH1K::Fill(Double_t x)
{
   // Increment bin with abscissa X by 1.
   //
   // if x is less than the low-edge of the first bin, the Underflow bin is incremented
   // if x is greater than the upper edge of last bin, the Overflow bin is incremented
   //
   // If the storage of the sum of squares of weights has been triggered,
   // via the function Sumw2, then the sum of the squares of weights is incremented
   // by 1 in the bin corresponding to x.

   fReady = 0;
   Int_t bin;
   fEntries++;
   bin =fXaxis.FindBin(x);
   if (bin == 0 || bin > fXaxis.GetNbins()) {
      if (!fgStatOverflows) return -1;
   }
   ++fTsumw;
   ++fTsumw2;
   fTsumwx  += x;
   fTsumwx2 += x*x;
   fReady = 0;
   if (fNIn == fN) Set(fN*2);
   AddAt(x,fNIn++);
   return bin;
}


//______________________________________________________________________________
Double_t TH1K::GetBinContent(Int_t bin) const
{
   // Return content of global bin number bin.

   if (!fReady) {
      ((TH1K*)this)->Sort();
      ((TH1K*)this)->fReady=1;
   }
   if (!fNIn)   return 0.;
   float x = GetBinCenter(bin);
   int left = TMath::BinarySearch(fNIn,fArray,x);
   int jl=left,jr=left+1,nk,nkmax =fKOrd;
   float fl,fr,ff=0.,ffmin=1.e-6;
   if (!nkmax) {nkmax = 3; ffmin = GetBinWidth(bin);}
   if (nkmax >= fNIn) nkmax = fNIn-1;
   for (nk = 1; nk <= nkmax || ff <= ffmin; nk++) {
      fl = (jl>=0  ) ? TMath::Abs(fArray[jl]-x) : 1.e+20;
      fr = (jr<fNIn) ? TMath::Abs(fArray[jr]-x) : 1.e+20;
      if (jl<0 && jr>=fNIn) break;
      if (fl < fr) { ff = fl; jl--;}
      else         { ff = fr; jr++;}
   }
   ((TH1K*)this)->fKCur = nk - 1;
   return fNIn * 0.5*fKCur/((float)(fNIn+1))*GetBinWidth(bin)/ff;
}


//______________________________________________________________________________
Double_t TH1K::GetBinError(Int_t bin) const
{
   // Return content of global bin error.

   return TMath::Sqrt(((double)(fNIn-fKCur+1))/((fNIn+1)*(fKCur-1)))*GetBinContent(bin);
}


//______________________________________________________________________________
void   TH1K::Reset(Option_t *option)
{
   // Reset.

   fNIn   =0;
   fReady = 0;
   TH1::Reset(option);
}


//______________________________________________________________________________
void TH1K::SavePrimitive(ostream &out, Option_t *option /*= ""*/)
{
   // Save primitive as a C++ statement(s) on output stream out
   // Note the following restrictions in the code generated:
   //  - variable bin size not implemented
   //  - Objects in list of functions not saved (fits)
   //  - Contours not saved

   char quote = '"';
   out<<"   "<<endl;
   out<<"   "<<"TH1 *";

   out<<GetName()<<" = new "<<ClassName()<<"("<<quote<<GetName()<<quote<<","<<quote<<GetTitle()<<quote
                 <<","<<GetXaxis()->GetNbins()
                 <<","<<GetXaxis()->GetXmin()
                 <<","<<GetXaxis()->GetXmax()
                 <<","<<fKOrd;
   out <<");"<<endl;

   if (fDirectory == 0) {
      out<<"   "<<GetName()<<"->SetDirectory(0);"<<endl;
   }
   if (TestBit(kNoStats)) {
      out<<"   "<<GetName()<<"->SetStats(0);"<<endl;
   }
   if (fOption.Length() != 0) {
      out<<"   "<<GetName()<<"->SetOption("<<quote<<fOption.Data()<<quote<<");"<<endl;
   }

   if (fNIn) {
      out<<"   Float_t Arr[]={"<<endl;
      for (int i=0; i<fNIn; i++) {
         out<< fArray[i];
         if (i != fNIn-1) {out<< ",";} else { out<< "};";}
         if (i%10 == 9)   {out<< endl;}
      }
      out<< endl;
      out<<"   for(int i=0;i<" << fNIn << ";i++)"<<GetName()<<"->Fill(Arr[i]);";
      out<< endl;
   }
   SaveFillAttributes(out,GetName(),0,1001);
   SaveLineAttributes(out,GetName(),1,1,1);
   SaveMarkerAttributes(out,GetName(),1,1,1);
   fXaxis.SaveAttributes(out,GetName(),"->GetXaxis()");
   fYaxis.SaveAttributes(out,GetName(),"->GetYaxis()");
   fZaxis.SaveAttributes(out,GetName(),"->GetZaxis()");
   TString opt = option;
   opt.ToLower();
   if (!opt.Contains("nodraw")) {
      out<<"   "<<GetName()<<"->Draw("
      <<quote<<option<<quote<<");"<<endl;
   }
}


//______________________________________________________________________________
static int TH1K_fcompare(const void *f1,const void *f2)
{
   // Compare.

   if (*((float*)f1) < *((float*)f2)) return -1;
   if (*((float*)f1) > *((float*)f2)) return  1;
   return 0;
}


//______________________________________________________________________________
void TH1K::Sort()
{
   // Sort.

   if (fNIn<2) return;
   qsort(GetArray(),fNIn,sizeof(Float_t),&TH1K_fcompare);
}

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