TCutG.cxx

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// @(#)root/graf:$Id: TCutG.cxx 37309 2010-12-06 00:10:29Z pcanal $
// Author: Rene Brun   16/05/97

/*************************************************************************
 * 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.             *
 *************************************************************************/


//______________________________________________________________________________
/* Begin_Html
<center><h2>Graphical cut class</h2></center>
A Graphical cut.
<p>
A TCutG object is a closed polygon defining a closed region in a x,y plot.
It can be created via the graphics editor option "CutG" or directly by
invoking its constructor. The first and last points should be the same.
<p>
To create a TCutG via the graphics editor, use the left button to select the
points building the contour of the cut. Click on the right button to close the
TCutG. When it is created via the graphics editor, the TCutG object is named
"CUTG". It is recommended to immediatly change the name by using the context
menu item "SetName". When the graphics editor is used, the names of the
variables X,Y are automatically taken from the current pad title.
<p>
Example:
<p>
Assume a TTree object T and:
<pre>
     Root > T.Draw("abs(fMomemtum)%fEtot")
</pre>
the TCutG members fVarX, fVary will be set to:
<pre>
     fVarx = fEtot
     fVary = abs(fMomemtum)
</pre>

A graphical cut can be used in a TTree selection expression:
<pre>
    Root > T.Draw("fEtot","cutg1")
</pre>
where "cutg1" is the name of an existing graphical cut.
<p>
Note that, as shown in the example above, a graphical cut may be used in a
selection expression when drawing TTrees expressions of 1-d, 2-d or
3-dimensions. The expressions used in TTree::Draw can reference the variables in
the fVarX, fVarY of the graphical cut plus other variables.
<p>
When the TCutG object is created by TTree::Draw, it is added to the list of special objects in
the main TROOT object pointed by gROOT. To retrieve a pointer to this object
from the code or command line, do:
<pre>
    TCutG *mycutg;
    mycutg = (TCutG*)gROOT->GetListOfSpecials()->FindObject("CUTG")
    mycutg->SetName("mycutg");
</pre>
<p>
When the TCutG is not created via TTree::Draw, one must set the variable names
corresponding to x,y if one wants to use the cut as input to TTree::Draw,eg
<pre>
   TCutG *cutg = new TCutG("mycut",5);
   cutg->SetVarX("y");
   cutg->SetVarY("x");
   cutg->SetPoint(0,-0.3586207,1.509534);
   cutg->SetPoint(1,-1.894181,-0.529661);
   cutg->SetPoint(2,0.07780173,-1.21822);
   cutg->SetPoint(3,-1.0375,-0.07944915);
   cutg->SetPoint(4,0.756681,0.1853814);
   cutg->SetPoint(5,-0.3586207,1.509534);
</pre>
   
Example of use of a TCutG in TTree::Draw:
<pre>
       tree.Draw("x:y","mycutg && z>0 %% sqrt(x)>1")
</pre>
<p>
A Graphical cut may be drawn via TGraph::Draw. It can be edited like a normal
TGraph.
<p>
A Graphical cut may be saved to a file via TCutG::Write.
End_Html */

#include <string.h>

#include "Riostream.h"
#include "TROOT.h"
#include "TCutG.h"
#include "TVirtualPad.h"
#include "TPaveText.h"
#include "TH2.h"
#include "TClass.h"
#include "TMath.h"

ClassImp(TCutG)


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

   fObjectX  = 0;
   fObjectY  = 0;
}


//______________________________________________________________________________
TCutG::TCutG(const TCutG &cutg)
      :TGraph(cutg)
{
   // TCutG copy constructor

   fVarX    = cutg.fVarX;
   fVarY    = cutg.fVarY;
   fObjectX = cutg.fObjectX;
   fObjectY = cutg.fObjectY;
}


//______________________________________________________________________________
TCutG::TCutG(const char *name, Int_t n)
      :TGraph(n)
{
   // TCutG normal constructor.

   fObjectX  = 0;
   fObjectY  = 0;
   SetName(name);
   delete gROOT->GetListOfSpecials()->FindObject(name);
   gROOT->GetListOfSpecials()->Add(this);

   // Take name of cut variables from pad title if title contains ":"
   if (gPad) {
      TPaveText *ptitle = (TPaveText*)gPad->FindObject("title");
      if (!ptitle) return;
      TText *ttitle = ptitle->GetLineWith(":");
      if (!ttitle) ttitle = ptitle->GetLineWith("{");
      if (!ttitle) ttitle = ptitle->GetLine(0);
      if (!ttitle) return;
      const char *title = ttitle->GetTitle();
      Int_t nch = strlen(title);
      char *vars = new char[nch+1];
      strlcpy(vars,title,nch+1);
      char *col = strstr(vars,":");
      if (col) {
         *col = 0;
         col++;
         char *brak = strstr(col," {");
         if (brak) *brak = 0;
         fVarY = vars;
         fVarX = col;
      } else {
         char *brak = strstr(vars," {");
         if (brak) *brak = 0;
         fVarX = vars;
      }
      delete [] vars;
   }
}


//______________________________________________________________________________
TCutG::TCutG(const char *name, Int_t n, const Float_t *x, const Float_t *y)
      :TGraph(n,x,y)
{
   // TCutG normal constructor.

   fObjectX  = 0;
   fObjectY  = 0;
   SetName(name);
   delete gROOT->GetListOfSpecials()->FindObject(name);
   gROOT->GetListOfSpecials()->Add(this);

   // Take name of cut variables from pad title if title contains ":"
   if (gPad) {
      TPaveText *ptitle = (TPaveText*)gPad->FindObject("title");
      if (!ptitle) return;
      TText *ttitle = ptitle->GetLineWith(":");
      if (!ttitle) ttitle = ptitle->GetLineWith("{");
      if (!ttitle) ttitle = ptitle->GetLine(0);
      if (!ttitle) return;
      const char *title = ttitle->GetTitle();
      Int_t nch = strlen(title);
      char *vars = new char[nch+1];
      strlcpy(vars,title,nch+1);
      char *col = strstr(vars,":");
      if (col) {
         *col = 0;
         col++;
         char *brak = strstr(col," {");
         if (brak) *brak = 0;
         fVarY = vars;
         fVarX = col;
      } else {
         char *brak = strstr(vars," {");
         if (brak) *brak = 0;
         fVarX = vars;
      }
      delete [] vars;
   }
}


//______________________________________________________________________________
TCutG::TCutG(const char *name, Int_t n, const Double_t *x, const Double_t *y)
      :TGraph(n,x,y)
{
   // TCutG normal constructor.

   fObjectX  = 0;
   fObjectY  = 0;
   SetName(name);
   delete gROOT->GetListOfSpecials()->FindObject(name);
   gROOT->GetListOfSpecials()->Add(this);

   // Take name of cut variables from pad title if title contains ":"
   if (gPad) {
      TPaveText *ptitle = (TPaveText*)gPad->FindObject("title");
      if (!ptitle) return;
      TText *ttitle = ptitle->GetLineWith(":");
      if (!ttitle) ttitle = ptitle->GetLineWith("{");
      if (!ttitle) ttitle = ptitle->GetLine(0);
      if (!ttitle) return;
      const char *title = ttitle->GetTitle();
      Int_t nch = strlen(title);
      char *vars = new char[nch+1];
      strlcpy(vars,title,nch+1);
      char *col = strstr(vars,":");
      if (col) {
         *col = 0;
         col++;
         char *brak = strstr(col," {");
         if (brak) *brak = 0;
         fVarY = vars;
         fVarX = col;
      } else {
         char *brak = strstr(vars," {");
         if (brak) *brak = 0;
         fVarX = vars;
      }
      delete [] vars;
   }
}


//______________________________________________________________________________
TCutG::~TCutG()
{
   // TCutG destructor.

   delete fObjectX;
   delete fObjectY;
   gROOT->GetListOfSpecials()->Remove(this);
}

//______________________________________________________________________________
Double_t TCutG::Area() const
{
   // Compute the area inside this TCutG
   // The algorithm uses Stoke's theorem over the border of the closed polygon.
   // Just as a reminder: Stoke's theorem reduces a surface integral
   // to a line integral over the border of the surface integral.
   Double_t a = 0;
   Int_t n = GetN();
   for (Int_t i=0;i<n-1;i++) {
      a += (fX[i]-fX[i+1])*(fY[i]+fY[i+1]);
   }
   a *= 0.5;
   return a;   
}

//______________________________________________________________________________
void TCutG::Center(Double_t &cx, Double_t &cy) const
{
   // Compute the center x,y of this TCutG
   // The algorithm uses Stoke's theorem over the border of the closed polygon.
   // Just as a reminder: Stoke's theorem reduces a surface integral
   // to a line integral over the border of the surface integral.
   Int_t n = GetN();
   Double_t a  = 0;
   cx = cy = 0;
   Double_t t;
   for (Int_t i=0;i<n-1;i++) {
      t   = 2*fX[i]*fY[i] + fY[i]*fX[i+1] + fX[i]*fY[i+1] + 2*fX[i+1]*fY[i+1];
      cx += (fX[i]-fX[i+1])*t;
      cy += (-fY[i]+fY[i+1])*t;
      a  += (fX[i]-fX[i+1])*(fY[i]+fY[i+1]);
   }
   a  *= 0.5;
   cx *= 1./(6*a);
   cy *= 1./(6*a);
}

//______________________________________________________________________________
Double_t TCutG::IntegralHist(TH2 *h, Option_t *option) const
{
   // Compute the integral of 2-d histogram h for all bins inside the cut
   // if option "width" is specified, the integral is the sum of
   // the bin contents multiplied by the bin width in x and in y.

   if (!h) return 0;
   Int_t n = GetN();
   Double_t xmin= 1e200;
   Double_t xmax = -xmin;
   Double_t ymin = xmin;
   Double_t ymax = xmax;
   for (Int_t i=0;i<n;i++) {
      if (fX[i] < xmin) xmin = fX[i];
      if (fX[i] > xmax) xmax = fX[i];
      if (fY[i] < ymin) ymin = fY[i];
      if (fY[i] > ymax) ymax = fY[i];
   }
   TAxis *xaxis = h->GetXaxis();
   TAxis *yaxis = h->GetYaxis();
   Int_t binx1 = xaxis->FindBin(xmin);
   Int_t binx2 = xaxis->FindBin(xmax);
   Int_t biny1 = yaxis->FindBin(ymin);
   Int_t biny2 = yaxis->FindBin(ymax);
   Int_t nbinsx = h->GetNbinsX();
   Stat_t integral = 0;

   // Loop on bins for which the bin center is in the cut
   TString opt = option;
   opt.ToLower();
   Bool_t width = kFALSE;
   if (opt.Contains("width")) width = kTRUE;
   Int_t bin, binx, biny;
   for (biny=biny1;biny<=biny2;biny++) {
      Double_t y = yaxis->GetBinCenter(biny);
      for (binx=binx1;binx<=binx2;binx++) {
         Double_t x = xaxis->GetBinCenter(binx);
         if (!IsInside(x,y)) continue;
         bin = binx +(nbinsx+2)*biny;
         if (width) integral += h->GetBinContent(bin)*xaxis->GetBinWidth(binx)*yaxis->GetBinWidth(biny);
         else       integral += h->GetBinContent(bin);
      }
   }
   return integral;
}


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

   char quote = '"';
   out<<"   "<<endl;
   if (gROOT->ClassSaved(TCutG::Class())) {
      out<<"   ";
   } else {
      out<<"   TCutG *";
   }
   out<<"cutg = new TCutG("<<quote<<GetName()<<quote<<","<<fNpoints<<");"<<endl;
   out<<"   cutg->SetVarX("<<quote<<GetVarX()<<quote<<");"<<endl;
   out<<"   cutg->SetVarY("<<quote<<GetVarY()<<quote<<");"<<endl;
   out<<"   cutg->SetTitle("<<quote<<GetTitle()<<quote<<");"<<endl;

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

   for (Int_t i=0;i<fNpoints;i++) {
      out<<"   cutg->SetPoint("<<i<<","<<fX[i]<<","<<fY[i]<<");"<<endl;
   }
   out<<"   cutg->Draw("
      <<quote<<option<<quote<<");"<<endl;
}

//______________________________________________________________________________
void TCutG::SetObjectX(TObject *obj) 
{
   // Set the X object (and delete the previous one if any).

   delete fObjectX;
   fObjectX = obj;
}

//______________________________________________________________________________
void TCutG::SetObjectY(TObject *obj)
{
   // Set the Y object (and delete the previous one if any).
   
   delete fObjectY;
   fObjectY = obj;
}

//______________________________________________________________________________
void TCutG::SetVarX(const char *varx)
{
   // Set X variable.

   fVarX = varx;
   delete fObjectX;
   fObjectX = 0;
}


//______________________________________________________________________________
void TCutG::SetVarY(const char *vary)
{
   // Set Y variable.

   fVarY = vary;
   delete fObjectY;
   fObjectY = 0;
}


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

   if (R__b.IsReading()) {
      R__b.ReadClassBuffer(TCutG::Class(), this);
      gROOT->GetListOfSpecials()->Add(this);
   } else {
      R__b.WriteClassBuffer(TCutG::Class(), this);
   }
}

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