TGraph2D Class Reference

Graphics object made of three arrays X, Y and Z with the same number of points each.

• Creating a TGraph2D
• Drawing options
• Examples
  • SURF1 Example
  • Fitting Example
  • PCOL Example
• Definition of the Delaunay triangulation (After B. Delaunay)

Creating a TGraph2D

This class has different constructors:

• With an array's dimension and three arrays x, y, and z:

  TGraph2D *g = new TGraph2D(n, x, y, z);

  x, y, z arrays can be doubles, floats, or ints.
• With an array's dimension only:

  TGraph2D *g = new TGraph2D(n);

  The internal arrays are then filled with SetPoint(). The following line fills the internal arrays at the position i with the values x, y, z.

  g->SetPoint(i, x, y, z);

• Without parameters:

  TGraph2D *g = new TGraph2D();

  again SetPoint() must be used to fill the internal arrays.
• From a file:

  TGraph2D *g = new TGraph2D("graph.dat");

  Arrays are read from the ASCII file "graph.dat" according to a specifies format. The default format is %lg %lg %lg

Note that in any of these three cases, SetPoint() can be used to change a data point or add a new one. If the data point index (i) is greater than the current size of the internal arrays, they are automatically extended.

Like TGraph some TGraph2D constructors do not have the TGraph2D title and name as parameters. For these constructors TGraph2D has the default title and name "Graph2D". To change the default title and name SetTitle and SetName should be called on the TGraph2D after its creation.

Drawing options

Specific drawing options can be used to paint a TGraph2D:

Option	Description
"TRI"	The Delaunay triangles are drawn using filled area. An hidden surface drawing technique is used. The surface is painted with the current fill area color. The edges of each triangles are painted with the current line color.
"TRIW"	The Delaunay triangles are drawn as wire frame.
"TRI1"	The Delaunay triangles are painted with color levels. The edges of each triangles are painted with the current line color.
"TRI2"	The Delaunay triangles are painted with color levels.
"P"	Draw a marker at each vertex.
"P0"	Draw a circle at each vertex. Each circle background is white.
"PCOL"	Draw a marker at each vertex. The color of each marker is defined according to its Z position.
"LINE"	Draw a 3D polyline.

A TGraph2D can be also drawn with any options valid to draw a 2D histogram (like COL, SURF, LEGO, CONT etc..).

When a TGraph2D is drawn with one of the 2D histogram drawing option, an intermediate 2D histogram is filled using the Delaunay triangles to interpolate the data set. The 2D histogram has equidistant bins along the X and Y directions. The number of bins along each direction can be change using SetNpx() and SetNpy(). Each bin is filled with the Z value found via a linear interpolation on the plane defined by the triangle above the (X,Y) coordinates of the bin center.

The existing (X,Y,Z) points can be randomly scattered. The Delaunay triangles are build in the (X,Y) plane. These 2D triangles are then used to define flat planes in (X,Y,Z) over which the interpolation is done to fill the 2D histogram. The 3D triangles int takes build a 3D surface in the form of tessellating triangles at various angles. The triangles found can be drawn in 3D with one of the TGraph2D specific drawing options.

The histogram generated by the Delaunay interpolation can be accessed using the GetHistogram() method.

The axis settings (title, ranges etc ...) can be changed accessing the axis via the GetXaxis GetYaxis and GetZaxis methods. They access the histogram axis created at drawing time only. Therefore they should called after the TGraph2D is drawn:

TGraph2D *g = new TGraph2D();
 
[...]
 
g->Draw("tri1");
gPad->Update();
g->GetXaxis()->SetTitle("X axis title");

Examples

SURF1 Example

{
   TCanvas *c = new TCanvas("c","Graph2D example",0,0,600,400);
   Double_t x, y, z, P = 6.;
   Int_t np = 200;
   TGraph2D *dt = new TGraph2D();
   dt->SetTitle("Graph title; X axis title; Y axis title; Z axis title");
   TRandom *r = new TRandom();
   for (Int_t N=0; N<np; N++) {
      x = 2*P*(r->Rndm(N))-P;
      y = 2*P*(r->Rndm(N))-P;
      z = (sin(x)/x)*(sin(y)/y)+0.2;
      dt->SetPoint(N,x,y,z);
   }
   gStyle->SetPalette(1);
   dt->Draw("surf1");
   return c;
}

Fitting Example

2D graphs can be fitted as shown by the following example:

 
#include <TMath.h>
#include <TGraph2D.h>
#include <TRandom.h>
#include <TStyle.h>
#include <TCanvas.h>
#include <TF2.h>
#include <TH1.h>
 
TCanvas* graph2dfit()
{
   gStyle->SetOptStat(0);
   gStyle->SetOptFit();
 
   TCanvas *c = new TCanvas("c","Graph2D example",0,0,600,800);
   c->Divide(2,3);
 
   Double_t rnd, x, y, z;
   Double_t e = 0.3;
   Int_t nd = 400;
   Int_t np = 10000;
 
   TRandom r;
   Double_t fl = 6;
   TF2  *f2 = new TF2("f2","1000*(([0]*sin(x)/x)*([1]*sin(y)/y))+200",
      -fl,fl,-fl,fl);
   f2->SetParameters(1,1);
   TGraph2D *dt = new TGraph2D();
 
   // Fill the 2D graph
   Double_t zmax = 0;
   for (Int_t N=0; N<nd; N++) {
      f2->GetRandom2(x,y);
      // Generate a random number in [-e,e]
      rnd = 2*r.Rndm()*e-e;
      z = f2->Eval(x,y)*(1+rnd);
      if (z>zmax) zmax = z;
      dt->SetPoint(N,x,y,z);
   }
 
   Double_t hr = 350;
   TH1D *h1 = new TH1D("h1",
   "#splitline{Difference between Original}{#splitline{function and Function}{with noise}}",
   100, -hr, hr);
   TH1D *h2 = new TH1D("h2",
   "#splitline{Difference between Original}{#splitline{function and Delaunay triangles}{interpolation}}",
   100, -hr, hr);
   TH1D *h3 = new TH1D("h3",
   "#splitline{Difference between Original}{function and Minuit fit}",
   500, -hr, hr);
 
   f2->SetParameters(0.5,1.5);
   dt->Fit(f2);
   TF2 *fit2 = (TF2*)dt->FindObject("f2");
 
   f2->SetParameters(1,1);
 
   for (Int_t N=0; N<np; N++) {
      f2->GetRandom2(x,y);
      // Generate a random number in [-e,e]
      rnd = 2*r.Rndm()*e-e;
      z = f2->Eval(x,y)*(1+rnd);
      h1->Fill(f2->Eval(x,y)-z);
      z = dt->Interpolate(x,y);
      h2->Fill(f2->Eval(x,y)-z);
      z = fit2->Eval(x,y);
      h3->Fill(f2->Eval(x,y)-z);
   }
 
   c->cd(1);
   f2->SetTitle("Original function with Graph2D points on top");
   f2->SetMaximum(zmax);
   gStyle->SetHistTopMargin(0);
   f2->Draw("surf1");
   dt->Draw("same p0");
 
   c->cd(3);
   dt->SetMargin(0.1);
   dt->SetFillColor(36);
   dt->SetTitle("Histogram produced with Delaunay interpolation");
   dt->Draw("surf4");
 
   c->cd(5);
   fit2->SetTitle("Minuit fit result on the Graph2D points");
   fit2->Draw("surf1");
 
   h1->SetFillColor(47);
   h2->SetFillColor(38);
   h3->SetFillColor(29);
 
   c->cd(2); h1->Fit("gaus","Q") ; h1->Draw();
   c->cd(4); h2->Fit("gaus","Q") ; h2->Draw();
   c->cd(6); h3->Fit("gaus","Q") ; h3->Draw();
   c->cd();
   return c;
}

PCOL Example

Example showing the PCOL option.

{
   TCanvas *c1 = new TCanvas("c1","Graph2D example",0,0,600,400);
   Double_t P = 5.;
   Int_t npx  = 20 ;
   Int_t npy  = 20 ;
   Double_t x = -P;
   Double_t y = -P;
   Double_t z;
   Int_t k = 0;
   Double_t dx = (2*P)/npx;
   Double_t dy = (2*P)/npy;
   TGraph2D *dt = new TGraph2D(npx*npy);
   dt->SetNpy(41);
   dt->SetNpx(40);
   for (Int_t i=0; i<npx; i++) {
      for (Int_t j=0; j<npy; j++) {
         z = sin(sqrt(x*x+y*y))+1;
         dt->SetPoint(k,x,y,z);
         k++;
         y = y+dy;
      }
      x = x+dx;
      y = -P;
   }
   gStyle->SetPalette(1);
   dt->SetMarkerStyle(20);
   dt->Draw("pcol");
   return c1;
}

Definition of the Delaunay triangulation (After B. Delaunay)

For a set S of points in the Euclidean plane, the unique triangulation DT(S) of S such that no point in S is inside the circumcircle of any triangle in DT(S). DT(S) is the dual of the Voronoi diagram of S. If n is the number of points in S, the Voronoi diagram of S is the partitioning of the plane containing S points into n convex polygons such that each polygon contains exactly one point and every point in a given polygon is closer to its central point than to any other. A Voronoi diagram is sometimes also known as a Dirichlet tessellation.

This applet gives a nice practical view of Delaunay triangulation and Voronoi diagram.

Definition at line 41 of file TGraph2D.h.

Public Member Functions
	TGraph2D ()
	Graph2D default constructor.
	TGraph2D (const char *filename, const char *format="%lg %lg %lg", Option_t *option="")
	Graph2D constructor reading input from filename filename is assumed to contain at least three columns of numbers.
	TGraph2D (const char *name, const char *title, Int_t n, Double_t *x, Double_t *y, Double_t *z)
	Graph2D constructor with name, title and three vectors of doubles as input.
	TGraph2D (const TGraph2D &)
	Graph2D copy constructor.
	TGraph2D (Int_t n)
	Graph2D constructor.
	TGraph2D (Int_t n, Double_t *x, Double_t *y, Double_t *z)
	Graph2D constructor with three vectors of doubles as input.
	TGraph2D (Int_t n, Float_t *x, Float_t *y, Float_t *z)
	Graph2D constructor with three vectors of floats as input.
	TGraph2D (Int_t n, Int_t *x, Int_t *y, Int_t *z)
	Graph2D constructor with three vectors of ints as input.
	TGraph2D (TH2 *h2)
	Graph2D constructor with a TH2 (h2) as input.
virtual	~TGraph2D ()
	TGraph2D destructor.
virtual void	AddPoint (Double_t x, Double_t y, Double_t z)
	Append a new point to the graph.
virtual void	Browse (TBrowser *)
	Browse.
virtual void	Clear (Option_t *option="")
	Free all memory allocated by this object.
virtual void	DirectoryAutoAdd (TDirectory *)
	Perform the automatic addition of the graph to the given directory.
Int_t	DistancetoPrimitive (Int_t px, Int_t py)
	Computes distance from point px,py to a graph.
virtual void	Draw (Option_t *option="P0")
	Specific drawing options can be used to paint a TGraph2D:
void	ExecuteEvent (Int_t event, Int_t px, Int_t py)
	Executes action corresponding to one event.
virtual TObject *	FindObject (const char *name) const
	search object named name in the list of functions
virtual TObject *	FindObject (const TObject *obj) const
	search object obj in the list of functions
virtual TFitResultPtr	Fit (const char *formula, Option_t *option="", Option_t *goption="")
	Fits this graph with function with name fname Predefined functions such as gaus, expo and poln are automatically created by ROOT.
virtual TFitResultPtr	Fit (TF2 *f2, Option_t *option="", Option_t *goption="")
	Fits this 2D graph with function f2.
virtual void	FitPanel ()
	Display a GUI panel with all graph fit options.
TList *	GetContourList (Double_t contour)
	Returns the X and Y graphs building a contour.
TDirectory *	GetDirectory () const
virtual Double_t	GetErrorX (Int_t bin) const
	This function is called by Graph2DFitChisquare.
virtual Double_t	GetErrorY (Int_t bin) const
	This function is called by Graph2DFitChisquare.
virtual Double_t	GetErrorZ (Int_t bin) const
	This function is called by Graph2DFitChisquare.
virtual Double_t *	GetEX () const
virtual Double_t *	GetEY () const
virtual Double_t *	GetEZ () const
TH2D *	GetHistogram (Option_t *option="")
	By default returns a pointer to the Delaunay histogram.
TList *	GetListOfFunctions () const
Double_t	GetMargin () const
Double_t	GetMaximum () const
Double_t	GetMinimum () const
Int_t	GetN () const
Int_t	GetNpx () const
Int_t	GetNpy () const
virtual Int_t	GetPoint (Int_t i, Double_t &x, Double_t &y, Double_t &z) const
	Get x, y and z values for point number i.
Double_t *	GetX () const
TAxis *	GetXaxis () const
	Get x axis of the graph.
Double_t	GetXmax () const
	Returns the X maximum.
virtual Double_t	GetXmaxE () const
Double_t	GetXmin () const
	Returns the X minimum.
virtual Double_t	GetXminE () const
Double_t *	GetY () const
TAxis *	GetYaxis () const
	Get y axis of the graph.
Double_t	GetYmax () const
	Returns the Y maximum.
virtual Double_t	GetYmaxE () const
Double_t	GetYmin () const
	Returns the Y minimum.
virtual Double_t	GetYminE () const
Double_t *	GetZ () const
TAxis *	GetZaxis () const
	Get z axis of the graph.
Double_t	GetZmax () const
	Returns the Z maximum.
virtual Double_t	GetZmaxE () const
Double_t	GetZmin () const
	Returns the Z minimum.
virtual Double_t	GetZminE () const
Double_t	Interpolate (Double_t x, Double_t y)
	Finds the z value at the position (x,y) thanks to the Delaunay interpolation.
TGraph2D &	operator= (const TGraph2D &)
	Graph2D operator "=".
void	Paint (Option_t *option="")
	Paints this 2D graph with its current attributes.
virtual void	Print (Option_t *chopt="") const
	Print 2D graph values.
TH1 *	Project (Option_t *option="x") const
	Projects a 2-d graph into 1 or 2-d histograms depending on the option parameter.
Int_t	RemovePoint (Int_t ipoint)
	Deletes point number ipoint.
virtual void	SavePrimitive (std::ostream &out, Option_t *option="")
	Saves primitive as a C++ statement(s) on output stream out.
virtual void	Scale (Double_t c1=1., Option_t *option="z")
	Multiply the values of a TGraph2D by a constant c1.
virtual void	Set (Int_t n)
	Set number of points in the 2D graph.
virtual void	SetDirectory (TDirectory *dir)
	By default when an 2D graph is created, it is added to the list of 2D graph objects in the current directory in memory.
virtual void	SetHistogram (TH2 *h)
	Sets the histogram to be filled.
void	SetMargin (Double_t m=0.1)
	Sets the extra space (in %) around interpolated area for the 2D histogram.
void	SetMarginBinsContent (Double_t z=0.)
	Sets the histogram bin height for points lying outside the TGraphDelaunay convex hull ie: the bins in the margin.
void	SetMaximum (Double_t maximum=-1111)
	Set maximum.
void	SetMaxIter (Int_t n=100000)
void	SetMinimum (Double_t minimum=-1111)
	Set minimum.
virtual void	SetName (const char *name)
	Changes the name of this 2D graph.
virtual void	SetNameTitle (const char *name, const char *title)
	Change the name and title of this 2D graph.
void	SetNpx (Int_t npx=40)
	Sets the number of bins along X used to draw the function.
void	SetNpy (Int_t npx=40)
	Sets the number of bins along Y used to draw the function.
virtual void	SetPoint (Int_t point, Double_t x, Double_t y, Double_t z)
	Sets point number n.
virtual void	SetTitle (const char *title="")
	Sets the 2D graph title.
Public Member Functions inherited from TNamed
	TNamed ()
	TNamed (const char *name, const char *title)
	TNamed (const TNamed &named)
	TNamed copy ctor.
	TNamed (const TString &name, const TString &title)
virtual	~TNamed ()
	TNamed destructor.
virtual TObject *	Clone (const char *newname="") const
	Make a clone of an object using the Streamer facility.
virtual Int_t	Compare (const TObject *obj) const
	Compare two TNamed objects.
virtual void	Copy (TObject &named) const
	Copy this to obj.
virtual void	FillBuffer (char *&buffer)
	Encode TNamed into output buffer.
virtual const char *	GetName () const
	Returns name of object.
virtual const char *	GetTitle () const
	Returns title of object.
virtual ULong_t	Hash () const
	Return hash value for this object.
virtual Bool_t	IsSortable () const
virtual void	ls (Option_t *option="") const
	List TNamed name and title.
TNamed &	operator= (const TNamed &rhs)
	TNamed assignment operator.
virtual Int_t	Sizeof () const
	Return size of the TNamed part of the TObject.
Public Member Functions inherited from TObject
	TObject ()
	TObject constructor.
	TObject (const TObject &object)
	TObject copy ctor.
virtual	~TObject ()
	TObject destructor.
void	AbstractMethod (const char *method) const
	Use this method to implement an "abstract" method that you don't want to leave purely abstract.
virtual void	AppendPad (Option_t *option="")
	Append graphics object to current pad.
ULong_t	CheckedHash ()
	Check and record whether this class has a consistent Hash/RecursiveRemove setup (*) and then return the regular Hash value for this object.
virtual const char *	ClassName () const
	Returns name of class to which the object belongs.
virtual void	Delete (Option_t *option="")
	Delete this object.
virtual void	DrawClass () const
	Draw class inheritance tree of the class to which this object belongs.
virtual TObject *	DrawClone (Option_t *option="") const
	Draw a clone of this object in the current selected pad for instance with: gROOT->SetSelectedPad(gPad).
virtual void	Dump () const
	Dump contents of object on stdout.
virtual void	Error (const char *method, const char *msgfmt,...) const
	Issue error message.
virtual void	Execute (const char *method, const char *params, Int_t *error=0)
	Execute method on this object with the given parameter string, e.g.
virtual void	Execute (TMethod *method, TObjArray *params, Int_t *error=0)
	Execute method on this object with parameters stored in the TObjArray.
virtual void	Fatal (const char *method, const char *msgfmt,...) const
	Issue fatal error message.
virtual Option_t *	GetDrawOption () const
	Get option used by the graphics system to draw this object.
virtual const char *	GetIconName () const
	Returns mime type name of object.
virtual char *	GetObjectInfo (Int_t px, Int_t py) const
	Returns string containing info about the object at position (px,py).
virtual Option_t *	GetOption () const
virtual UInt_t	GetUniqueID () const
	Return the unique object id.
virtual Bool_t	HandleTimer (TTimer *timer)
	Execute action in response of a timer timing out.
Bool_t	HasInconsistentHash () const
	Return true is the type of this object is known to have an inconsistent setup for Hash and RecursiveRemove (i.e.
virtual void	Info (const char *method, const char *msgfmt,...) const
	Issue info message.
virtual Bool_t	InheritsFrom (const char *classname) const
	Returns kTRUE if object inherits from class "classname".
virtual Bool_t	InheritsFrom (const TClass *cl) const
	Returns kTRUE if object inherits from TClass cl.
virtual void	Inspect () const
	Dump contents of this object in a graphics canvas.
void	InvertBit (UInt_t f)
Bool_t	IsDestructed () const
	IsDestructed.
virtual Bool_t	IsEqual (const TObject *obj) const
	Default equal comparison (objects are equal if they have the same address in memory).
virtual Bool_t	IsFolder () const
	Returns kTRUE in case object contains browsable objects (like containers or lists of other objects).
R__ALWAYS_INLINE Bool_t	IsOnHeap () const
R__ALWAYS_INLINE Bool_t	IsZombie () const
void	MayNotUse (const char *method) const
	Use this method to signal that a method (defined in a base class) may not be called in a derived class (in principle against good design since a child class should not provide less functionality than its parent, however, sometimes it is necessary).
virtual Bool_t	Notify ()
	This method must be overridden to handle object notification.
void	Obsolete (const char *method, const char *asOfVers, const char *removedFromVers) const
	Use this method to declare a method obsolete.
void	operator delete (void *ptr)
	Operator delete.
void	operator delete[] (void *ptr)
	Operator delete [].
void *	operator new (size_t sz)
void *	operator new (size_t sz, void *vp)
void *	operator new[] (size_t sz)
void *	operator new[] (size_t sz, void *vp)
TObject &	operator= (const TObject &rhs)
	TObject assignment operator.
virtual void	Pop ()
	Pop on object drawn in a pad to the top of the display list.
virtual Int_t	Read (const char *name)
	Read contents of object with specified name from the current directory.
virtual void	RecursiveRemove (TObject *obj)
	Recursively remove this object from a list.
void	ResetBit (UInt_t f)
virtual void	SaveAs (const char *filename="", Option_t *option="") const
	Save this object in the file specified by filename.
void	SetBit (UInt_t f)
void	SetBit (UInt_t f, Bool_t set)
	Set or unset the user status bits as specified in f.
virtual void	SetDrawOption (Option_t *option="")
	Set drawing option for object.
virtual void	SetUniqueID (UInt_t uid)
	Set the unique object id.
virtual void	SysError (const char *method, const char *msgfmt,...) const
	Issue system error message.
R__ALWAYS_INLINE Bool_t	TestBit (UInt_t f) const
Int_t	TestBits (UInt_t f) const
virtual void	UseCurrentStyle ()
	Set current style settings in this object This function is called when either TCanvas::UseCurrentStyle or TROOT::ForceStyle have been invoked.
virtual void	Warning (const char *method, const char *msgfmt,...) const
	Issue warning message.
virtual Int_t	Write (const char *name=0, Int_t option=0, Int_t bufsize=0)
	Write this object to the current directory.
virtual Int_t	Write (const char *name=0, Int_t option=0, Int_t bufsize=0) const
	Write this object to the current directory.
Public Member Functions inherited from TAttLine
	TAttLine ()
	AttLine default constructor.
	TAttLine (Color_t lcolor, Style_t lstyle, Width_t lwidth)
	AttLine normal constructor.
virtual	~TAttLine ()
	AttLine destructor.
void	Copy (TAttLine &attline) const
	Copy this line attributes to a new TAttLine.
Int_t	DistancetoLine (Int_t px, Int_t py, Double_t xp1, Double_t yp1, Double_t xp2, Double_t yp2)
	Compute distance from point px,py to a line.
virtual Color_t	GetLineColor () const
	Return the line color.
virtual Style_t	GetLineStyle () const
	Return the line style.
virtual Width_t	GetLineWidth () const
	Return the line width.
virtual void	Modify ()
	Change current line attributes if necessary.
virtual void	ResetAttLine (Option_t *option="")
	Reset this line attributes to default values.
virtual void	SaveLineAttributes (std::ostream &out, const char *name, Int_t coldef=1, Int_t stydef=1, Int_t widdef=1)
	Save line attributes as C++ statement(s) on output stream out.
virtual void	SetLineAttributes ()
	Invoke the DialogCanvas Line attributes.
virtual void	SetLineColor (Color_t lcolor)
	Set the line color.
virtual void	SetLineColorAlpha (Color_t lcolor, Float_t lalpha)
	Set a transparent line color.
virtual void	SetLineStyle (Style_t lstyle)
	Set the line style.
virtual void	SetLineWidth (Width_t lwidth)
	Set the line width.
Public Member Functions inherited from TAttFill
	TAttFill ()
	AttFill default constructor.
	TAttFill (Color_t fcolor, Style_t fstyle)
	AttFill normal constructor.
virtual	~TAttFill ()
	AttFill destructor.
void	Copy (TAttFill &attfill) const
	Copy this fill attributes to a new TAttFill.
virtual Color_t	GetFillColor () const
	Return the fill area color.
virtual Style_t	GetFillStyle () const
	Return the fill area style.
virtual Bool_t	IsTransparent () const
virtual void	Modify ()
	Change current fill area attributes if necessary.
virtual void	ResetAttFill (Option_t *option="")
	Reset this fill attributes to default values.
virtual void	SaveFillAttributes (std::ostream &out, const char *name, Int_t coldef=1, Int_t stydef=1001)
	Save fill attributes as C++ statement(s) on output stream out.
virtual void	SetFillAttributes ()
	Invoke the DialogCanvas Fill attributes.
virtual void	SetFillColor (Color_t fcolor)
	Set the fill area color.
virtual void	SetFillColorAlpha (Color_t fcolor, Float_t falpha)
	Set a transparent fill color.
virtual void	SetFillStyle (Style_t fstyle)
	Set the fill area style.
Public Member Functions inherited from TAttMarker
	TAttMarker ()
	TAttMarker default constructor.
	TAttMarker (Color_t color, Style_t style, Size_t msize)
	TAttMarker normal constructor.
virtual	~TAttMarker ()
	TAttMarker destructor.
void	Copy (TAttMarker &attmarker) const
	Copy this marker attributes to a new TAttMarker.
virtual Color_t	GetMarkerColor () const
	Return the marker color.
virtual Size_t	GetMarkerSize () const
	Return the marker size.
virtual Style_t	GetMarkerStyle () const
	Return the marker style.
virtual void	Modify ()
	Change current marker attributes if necessary.
virtual void	ResetAttMarker (Option_t *toption="")
	Reset this marker attributes to the default values.
virtual void	SaveMarkerAttributes (std::ostream &out, const char *name, Int_t coldef=1, Int_t stydef=1, Int_t sizdef=1)
	Save line attributes as C++ statement(s) on output stream out.
virtual void	SetMarkerAttributes ()
	Invoke the DialogCanvas Marker attributes.
virtual void	SetMarkerColor (Color_t mcolor=1)
	Set the marker color.
virtual void	SetMarkerColorAlpha (Color_t mcolor, Float_t malpha)
	Set a transparent marker color.
virtual void	SetMarkerSize (Size_t msize=1)
	Set the marker size.
virtual void	SetMarkerStyle (Style_t mstyle=1)
	Set the marker style.

Protected Member Functions
void	Build (Int_t n)
	Creates the 2D graph basic data structure.
Protected Member Functions inherited from TObject
virtual void	DoError (int level, const char *location, const char *fmt, va_list va) const
	Interface to ErrorHandler (protected).
void	MakeZombie ()

Protected Attributes
TObject *	fDelaunay
	! Pointer to Delaunay interpolator object
TDirectory *	fDirectory
	!Pointer to directory holding this 2D graph
TList *	fFunctions
	Pointer to list of functions (fits and user)
TH2D *	fHistogram
	!2D histogram of z values linearly interpolated on the triangles
Double_t	fMargin
	Extra space (in %) around interpolated area for fHistogram.
Double_t	fMaximum
	Maximum value for plotting along z.
Int_t	fMaxIter
	Maximum number of iterations to find Delaunay triangles.
Double_t	fMinimum
	Minimum value for plotting along z.
Int_t	fNpoints
	Number of points in the data set.
Int_t	fNpx
	Number of bins along X in fHistogram.
Int_t	fNpy
	Number of bins along Y in fHistogram.
TVirtualHistPainter *	fPainter
	!Pointer to histogram painter
Int_t	fSize
	!Real size of fX, fY and fZ
Double_t *	fX
	[fNpoints]
Double_t *	fY
	[fNpoints] Data set to be plotted
Double_t *	fZ
	[fNpoints]
Double_t	fZout
	fHistogram bin height for points lying outside the interpolated area
Protected Attributes inherited from TNamed
TString	fName
TString	fTitle
Protected Attributes inherited from TAttLine
Color_t	fLineColor
	Line color.
Style_t	fLineStyle
	Line style.
Width_t	fLineWidth
	Line width.
Protected Attributes inherited from TAttFill
Color_t	fFillColor
	Fill area color.
Style_t	fFillStyle
	Fill area style.
Protected Attributes inherited from TAttMarker
Color_t	fMarkerColor
	Marker color.
Size_t	fMarkerSize
	Marker size.
Style_t	fMarkerStyle
	Marker style.

Private Types
enum	EStatusBits { kOldInterpolation = BIT(15) }

Private Member Functions
void	CreateInterpolator (Bool_t oldInterp)
	Add a TGraphDelaunay in the list of the fHistogram's functions.

Private Attributes
Bool_t	fUserHisto

Additional Inherited Members
Public Types inherited from TObject
enum	{   kIsOnHeap = 0x01000000 , kNotDeleted = 0x02000000 , kZombie = 0x04000000 , kInconsistent = 0x08000000 ,   kBitMask = 0x00ffffff }
enum	{ kSingleKey = BIT(0) , kOverwrite = BIT(1) , kWriteDelete = BIT(2) }
enum	EDeprecatedStatusBits { kObjInCanvas = BIT(3) }
enum	EStatusBits {   kCanDelete = BIT(0) , kMustCleanup = BIT(3) , kIsReferenced = BIT(4) , kHasUUID = BIT(5) ,   kCannotPick = BIT(6) , kNoContextMenu = BIT(8) , kInvalidObject = BIT(13) }
Static Public Member Functions inherited from TObject
static Longptr_t	GetDtorOnly ()
	Return destructor only flag.
static Bool_t	GetObjectStat ()
	Get status of object stat flag.
static void	SetDtorOnly (void *obj)
	Set destructor only flag.
static void	SetObjectStat (Bool_t stat)
	Turn on/off tracking of objects in the TObjectTable.
Static Public Member Functions inherited from TAttMarker
static Width_t	GetMarkerLineWidth (Style_t style)
	Internal helper function that returns the line width of the given marker style (0 = filled marker)
static Style_t	GetMarkerStyleBase (Style_t style)
	Internal helper function that returns the corresponding marker style with line width 1 for the given style.
Protected Types inherited from TObject
enum	{ kOnlyPrepStep = BIT(3) }

#include <TGraph2D.h>

Inheritance diagram for TGraph2D:

Member Enumeration Documentation

EStatusBits

enum TGraph2D::EStatusBits

private

Enumerator
kOldInterpolation

Definition at line 69 of file TGraph2D.h.

Constructor & Destructor Documentation

TGraph2D() [1/9]

TGraph2D::TGraph2D

(

)

Graph2D default constructor.

Definition at line 239 of file TGraph2D.cxx.

TGraph2D() [2/9]

TGraph2D::TGraph2D

(

Int_t

n

)

Graph2D constructor.

The arrays fX, fY and fZ should be filled via calls to SetPoint

Definition at line 389 of file TGraph2D.cxx.

TGraph2D() [3/9]

TGraph2D::TGraph2D	(	Int_t	n,
		Int_t *	x,
		Int_t *	y,
		Int_t *	z
	)

Graph2D constructor with three vectors of ints as input.

Definition at line 266 of file TGraph2D.cxx.

TGraph2D() [4/9]

TGraph2D::TGraph2D	(	Int_t	n,
		Float_t *	x,
		Float_t *	y,
		Float_t *	z
	)

Graph2D constructor with three vectors of floats as input.

Definition at line 284 of file TGraph2D.cxx.

TGraph2D() [5/9]

TGraph2D::TGraph2D	(	Int_t	n,
		Double_t *	x,
		Double_t *	y,
		Double_t *	z
	)

Graph2D constructor with three vectors of doubles as input.

Definition at line 302 of file TGraph2D.cxx.

TGraph2D() [6/9]

TGraph2D::TGraph2D

(

TH2 *

h2

)

Graph2D constructor with a TH2 (h2) as input.

Only the h2's bins within the X and Y axis ranges are used. Empty bins, recognized when both content and errors are zero, are excluded.

Definition at line 322 of file TGraph2D.cxx.

TGraph2D() [7/9]

TGraph2D::TGraph2D	(	const char *	name,
		const char *	title,
		Int_t	n,
		Double_t *	x,
		Double_t *	y,
		Double_t *	z
	)

Graph2D constructor with name, title and three vectors of doubles as input.

name : name of 2D graph (avoid blanks) title : 2D graph title if title is of the form "stringt;stringx;stringy;stringz" the 2D graph title is set to stringt, the x axis title to stringx, the y axis title to stringy,etc

Definition at line 369 of file TGraph2D.cxx.

TGraph2D() [8/9]

TGraph2D::TGraph2D	(	const char *	filename,
		const char *	format = "%lg %lg %lg",
		Option_t *	option = ""
	)

Graph2D constructor reading input from filename filename is assumed to contain at least three columns of numbers.

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 instantiation is about 2 times slower.

Definition at line 411 of file TGraph2D.cxx.

TGraph2D() [9/9]

TGraph2D::TGraph2D

(

const TGraph2D &

g

)

Graph2D copy constructor.

copy everything apart from the list of contained functions

Definition at line 531 of file TGraph2D.cxx.

~TGraph2D()

TGraph2D::~TGraph2D ( )

virtual

TGraph2D destructor.

Definition at line 557 of file TGraph2D.cxx.

Member Function Documentation

AddPoint()

virtual void TGraph2D::AddPoint ( Double_t  x, Double_t  y, Double_t  z  )

inlinevirtual

Append a new point to the graph.

Definition at line 93 of file TGraph2D.h.

Browse()

void TGraph2D::Browse ( TBrowser *  )

virtual

Browse.

Reimplemented from TObject.

Definition at line 648 of file TGraph2D.cxx.

Build()

void TGraph2D::Build ( Int_t  n )

protected

Creates the 2D graph basic data structure.

Definition at line 611 of file TGraph2D.cxx.

Clear()

void TGraph2D::Clear ( Option_t *  option = "" )

virtual

Free all memory allocated by this object.

Reimplemented from TNamed.

Definition at line 658 of file TGraph2D.cxx.

CreateInterpolator()

void TGraph2D::CreateInterpolator ( Bool_t  oldInterp )

private

Add a TGraphDelaunay in the list of the fHistogram's functions.

Definition at line 1073 of file TGraph2D.cxx.

DirectoryAutoAdd()

void TGraph2D::DirectoryAutoAdd ( TDirectory *  dir )

virtual

Perform the automatic addition of the graph to the given directory.

Note this function is called in place when the semantic requires this object to be added to a directory (I.e. when being read from a TKey or being Cloned)

Definition at line 692 of file TGraph2D.cxx.

DistancetoPrimitive()

Int_t TGraph2D::DistancetoPrimitive ( Int_t  px, Int_t  py  )

virtual

Computes distance from point px,py to a graph.

Reimplemented from TObject.

Definition at line 707 of file TGraph2D.cxx.

Draw()

void TGraph2D::Draw ( Option_t *  option = "P0" )

virtual

Specific drawing options can be used to paint a TGraph2D:

• "TRI" : The Delaunay triangles are drawn using filled area. An hidden surface drawing technique is used. The surface is painted with the current fill area color. The edges of each triangles are painted with the current line color.
• "TRIW" : The Delaunay triangles are drawn as wire frame
• "TRI1" : The Delaunay triangles are painted with color levels. The edges of each triangles are painted with the current line color.
• "TRI2" : the Delaunay triangles are painted with color levels.
• "P" : Draw a marker at each vertex
• "P0" : Draw a circle at each vertex. Each circle background is white.
• "PCOL" : Draw a marker at each vertex. The color of each marker is defined according to its Z position.
• "CONT" : Draw contours
• "LINE" : Draw a 3D polyline

A TGraph2D can be also drawn with ANY options valid to draw a 2D histogram.

When a TGraph2D is drawn with one of the 2D histogram drawing option, a intermediate 2D histogram is filled using the Delaunay triangles technique to interpolate the data set.

Reimplemented from TObject.

Definition at line 739 of file TGraph2D.cxx.

ExecuteEvent()

void TGraph2D::ExecuteEvent ( Int_t  event, Int_t  px, Int_t  py  )

virtual

Executes action corresponding to one event.

Reimplemented from TObject.

Definition at line 759 of file TGraph2D.cxx.

FindObject() [1/2]

TObject * TGraph2D::FindObject ( const char *  name ) const

virtual

search object named name in the list of functions

Reimplemented from TObject.

Definition at line 768 of file TGraph2D.cxx.

FindObject() [2/2]

TObject * TGraph2D::FindObject ( const TObject *  obj ) const

virtual

search object obj in the list of functions

Reimplemented from TObject.

Definition at line 778 of file TGraph2D.cxx.

Fit() [1/2]

TFitResultPtr TGraph2D::Fit ( const char *  fname, Option_t *  option = "", Option_t *  goption = ""  )

virtual

Fits this graph with function with name fname Predefined functions such as gaus, expo and poln are automatically created by ROOT.

fname can also be a formula, accepted by the linear fitter (linear parts divided by "++" sign), for example "x++sin(y)" for fitting "[0]*x+[1]*sin(y)"

Definition at line 792 of file TGraph2D.cxx.

Fit() [2/2]

TFitResultPtr TGraph2D::Fit ( TF2 *  f2, Option_t *  option = "", Option_t *  goption = ""  )

virtual

Fits this 2D graph with function f2.

f2 is an already predefined function created by TF2. Predefined functions such as gaus, expo and poln are automatically created by ROOT.

The list of fit options is given in parameter option:

Option	Description
"W"	Ignore all point errors when fitting a TGraph2DErrors
"U"	Use a User specified fitting algorithm (via SetFCN)
"Q"	Quiet mode (minimum printing)
"V"	Verbose mode (default is between Q and V)
"R"	Use the Range specified in the function range
"N"	Do not store the graphics function, do not draw
"0"	Do not plot the result of the fit. By default the fitted function is drawn unless the option "N" above is specified.
"+"	Add this new fitted function to the list of fitted functions (by default, any previous function is deleted)
"C"	In case of linear fitting, not calculate the chisquare (saves time)
"EX0"	When fitting a TGraph2DErrors do not consider errors in the X,Y coordinates
"ROB"	In case of linear fitting, compute the LTS regression coefficients (robust (resistant) regression), using the default fraction of good points "ROB=0.x" - compute the LTS regression coefficients, using 0.x as a fraction of good points
"S"	The result of the fit is returned in the TFitResultPtr (see below Access to the Fit Result)

In order to use the Range option, one must first create a function with the expression to be fitted. For example, if your graph2d has a defined range between -4 and 4 and you want to fit a gaussian only in the interval 1 to 3, you can do:

TF2 *f2 = new TF2("f2","gaus",1,3);
graph2d->Fit("f2","R");

Setting initial conditions

Parameters must be initialized before invoking the Fit function. The setting of the parameter initial values is automatic for the predefined functions : poln, expo, gaus. One can however disable this automatic computation by specifying the option "B". You can specify boundary limits for some or all parameters via

f2->SetParLimits(p_number, parmin, parmax);

if parmin>=parmax, the parameter is fixed Note that you are not forced to fix the limits for all parameters. For example, if you fit a function with 6 parameters, you can do:

func->SetParameters(0,3.1,1.e-6,0.1,-8,100);
func->SetParLimits(4,-10,-4);
func->SetParLimits(5, 1,1);

With this setup, parameters 0->3 can vary freely Parameter 4 has boundaries [-10,-4] with initial value -8 Parameter 5 is fixed to 100.

Fit range

The fit range can be specified in two ways:

• specify rxmax > rxmin (default is rxmin=rxmax=0)
• specify the option "R". In this case, the function will be taken instead of the full graph range.

Changing the fitting function

By default a chi2 fitting function is used for fitting a TGraph. The function is implemented in FitUtil::EvaluateChi2. In case of TGraph2DErrors an effective chi2 is used (see TGraphErrors fit in TGraph::Fit) and is implemented in FitUtil::EvaluateChi2Effective To specify a User defined fitting function, specify option "U" and call the following functions:

TVirtualFitter::Fitter(mygraph)->SetFCN(MyFittingFunction)

where MyFittingFunction is of type:

extern void MyFittingFunction(Int_t &npar, Double_t *gin, Double_t &f, Double_t *u, Int_t flag);

Associated functions

One or more object (typically a TF2*) can be added to the list of functions (fFunctions) associated to each graph. When TGraph::Fit is invoked, the fitted function is added to this list. Given a graph gr, one can retrieve an associated function with: TF2 *myfunc = gr->GetFunction("myfunc");

Access to the fit results

The function returns a TFitResultPtr which can hold a pointer to a TFitResult object. By default the TFitResultPtr contains only the status of the fit and it converts automatically to an integer. If the option "S" is instead used, TFitResultPtr contains the TFitResult and behaves as a smart pointer to it. For example one can do:

TFitResultPtr r = graph->Fit("myFunc","S");
TMatrixDSym cov = r->GetCovarianceMatrix();  //  to access the covariance matrix
Double_t par0   = r->Value(0); // retrieve the value for the parameter 0
Double_t err0   = r->Error(0); // retrieve the error for the parameter 0
r->Print("V");     // print full information of fit including covariance matrix
r->Write();        // store the result in a file

The fit parameters, error and chi2 (but not covariance matrix) can be retrieved also from the fitted function. If the graph is made persistent, the list of associated functions is also persistent. Given a pointer (see above) to an associated function myfunc, one can retrieve the function/fit parameters with calls such as:

Double_t chi2 = myfunc->GetChisquare();
Double_t par0 = myfunc->GetParameter(0); //value of 1st parameter
Double_t err0 = myfunc->GetParError(0);  //error on first parameter

Fit Statistics

You can change the statistics box to display the fit parameters with the TStyle::SetOptFit(mode) method. This mode has four digits. mode = pcev (default = 0111)

• v = 1; print name/values of parameters
• e = 1; print errors (if e=1, v must be 1)
• c = 1; print Chisquare/Number of degrees of freedom
• p = 1; print Probability

For example: gStyle->SetOptFit(1011); prints the fit probability, parameter names/values, and errors. You can change the position of the statistics box with these lines (where g is a pointer to the TGraph):

Root > TPaveStats *st = (TPaveStats*)g->GetListOfFunctions()->FindObject("stats")
Root > st->SetX1NDC(newx1); //new x start position
Root > st->SetX2NDC(newx2); //new x end position

Definition at line 947 of file TGraph2D.cxx.

FitPanel()

void TGraph2D::FitPanel ( )

virtual

Display a GUI panel with all graph fit options.

See class TFitEditor for example

Definition at line 966 of file TGraph2D.cxx.

GetContourList()

TList * TGraph2D::GetContourList

(

Double_t

contour

)

Returns the X and Y graphs building a contour.

A contour level may consist in several parts not connected to each other. This function returns them in a graphs' list.

Definition at line 1025 of file TGraph2D.cxx.

GetDirectory()

TDirectory * TGraph2D::GetDirectory ( ) const

inline

Definition at line 106 of file TGraph2D.h.

GetErrorX()

Double_t TGraph2D::GetErrorX ( Int_t  bin ) const

virtual

This function is called by Graph2DFitChisquare.

It always returns a negative value. Real implementation in TGraph2DErrors

Reimplemented in TGraph2DErrors.

Definition at line 1044 of file TGraph2D.cxx.

GetErrorY()

Double_t TGraph2D::GetErrorY ( Int_t  bin ) const

virtual

This function is called by Graph2DFitChisquare.

It always returns a negative value. Real implementation in TGraph2DErrors

Reimplemented in TGraph2DErrors.

Definition at line 1054 of file TGraph2D.cxx.

GetErrorZ()

Double_t TGraph2D::GetErrorZ ( Int_t  bin ) const

virtual

This function is called by Graph2DFitChisquare.

It always returns a negative value. Real implementation in TGraph2DErrors

Reimplemented in TGraph2DErrors.

Definition at line 1064 of file TGraph2D.cxx.

GetEX()

virtual Double_t * TGraph2D::GetEX ( ) const

inlinevirtual

Reimplemented in TGraph2DErrors.

Definition at line 124 of file TGraph2D.h.

GetEY()

virtual Double_t * TGraph2D::GetEY ( ) const

inlinevirtual

Reimplemented in TGraph2DErrors.

Definition at line 125 of file TGraph2D.h.

GetEZ()

virtual Double_t * TGraph2D::GetEZ ( ) const

inlinevirtual

Reimplemented in TGraph2DErrors.

Definition at line 126 of file TGraph2D.h.

GetHistogram()

TH2D * TGraph2D::GetHistogram

(

Option_t *

option = ""

)

By default returns a pointer to the Delaunay histogram.

If fHistogram doesn't exist, books the 2D histogram fHistogram with a margin around the hull. Calls TGraphDelaunay::Interpolate at each bin centre to build up an interpolated 2D histogram.

If the "empty" option is selected, returns an empty histogram booked with the limits of fX, fY and fZ. This option is used when the data set is drawn with markers only. In that particular case there is no need to find the Delaunay triangles.

By default use the new interpolation routine based on Triangles If the option "old" the old interpolation is used

Definition at line 1108 of file TGraph2D.cxx.

GetListOfFunctions()

TList * TGraph2D::GetListOfFunctions ( ) const

inline

Definition at line 110 of file TGraph2D.h.

GetMargin()

Double_t TGraph2D::GetMargin ( ) const

inline

Definition at line 114 of file TGraph2D.h.

GetMaximum()

Double_t TGraph2D::GetMaximum ( ) const

inline

Definition at line 115 of file TGraph2D.h.

GetMinimum()

Double_t TGraph2D::GetMinimum ( ) const

inline

Definition at line 116 of file TGraph2D.h.

GetN()

Int_t TGraph2D::GetN ( ) const

inline

Definition at line 120 of file TGraph2D.h.

GetNpx()

Int_t TGraph2D::GetNpx ( ) const

inline

Definition at line 107 of file TGraph2D.h.

GetNpy()

Int_t TGraph2D::GetNpy ( ) const

inline

Definition at line 108 of file TGraph2D.h.

GetPoint()

Int_t TGraph2D::GetPoint ( Int_t  i, Double_t &  x, Double_t &  y, Double_t &  z  ) const

virtual

Get x, y and z values for point number i.

The function returns -1 in case of an invalid request or the point number otherwise

Definition at line 1315 of file TGraph2D.cxx.

GetX()

Double_t * TGraph2D::GetX ( ) const

inline

Definition at line 121 of file TGraph2D.h.

GetXaxis()

TAxis * TGraph2D::GetXaxis

(

)

const

Get x axis of the graph.

Definition at line 990 of file TGraph2D.cxx.

GetXmax()

Double_t TGraph2D::GetXmax

(

)

const

Returns the X maximum.

Definition at line 1249 of file TGraph2D.cxx.

GetXmaxE()

virtual Double_t TGraph2D::GetXmaxE ( ) const

inlinevirtual

Reimplemented in TGraph2DErrors.

Definition at line 133 of file TGraph2D.h.

GetXmin()

Double_t TGraph2D::GetXmin

(

)

const

Returns the X minimum.

Definition at line 1260 of file TGraph2D.cxx.

GetXminE()

virtual Double_t TGraph2D::GetXminE ( ) const

inlinevirtual

Reimplemented in TGraph2DErrors.

Definition at line 134 of file TGraph2D.h.

GetY()

Double_t * TGraph2D::GetY ( ) const

inline

Definition at line 122 of file TGraph2D.h.

GetYaxis()

TAxis * TGraph2D::GetYaxis

(

)

const

Get y axis of the graph.

Definition at line 1001 of file TGraph2D.cxx.

GetYmax()

Double_t TGraph2D::GetYmax

(

)

const

Returns the Y maximum.

Definition at line 1271 of file TGraph2D.cxx.

GetYmaxE()

virtual Double_t TGraph2D::GetYmaxE ( ) const

inlinevirtual

Reimplemented in TGraph2DErrors.

Definition at line 135 of file TGraph2D.h.

GetYmin()

Double_t TGraph2D::GetYmin

(

)

const

Returns the Y minimum.

Definition at line 1282 of file TGraph2D.cxx.

GetYminE()

virtual Double_t TGraph2D::GetYminE ( ) const

inlinevirtual

Reimplemented in TGraph2DErrors.

Definition at line 136 of file TGraph2D.h.

GetZ()

Double_t * TGraph2D::GetZ ( ) const

inline

Definition at line 123 of file TGraph2D.h.

GetZaxis()

TAxis * TGraph2D::GetZaxis

(

)

const

Get z axis of the graph.

Definition at line 1012 of file TGraph2D.cxx.

GetZmax()

Double_t TGraph2D::GetZmax

(

)

const

Returns the Z maximum.

Definition at line 1293 of file TGraph2D.cxx.

GetZmaxE()

virtual Double_t TGraph2D::GetZmaxE ( ) const

inlinevirtual

Reimplemented in TGraph2DErrors.

Definition at line 137 of file TGraph2D.h.

GetZmin()

Double_t TGraph2D::GetZmin

(

)

const

Returns the Z minimum.

Definition at line 1304 of file TGraph2D.cxx.

GetZminE()

virtual Double_t TGraph2D::GetZminE ( ) const

inlinevirtual

Reimplemented in TGraph2DErrors.

Definition at line 138 of file TGraph2D.h.

Interpolate()

Double_t TGraph2D::Interpolate	(	Double_t	x,
		Double_t	y
	)

Finds the z value at the position (x,y) thanks to the Delaunay interpolation.

Definition at line 1329 of file TGraph2D.cxx.

operator=()

TGraph2D & TGraph2D::operator=

(

const TGraph2D &

g

)

Graph2D operator "=".

Definition at line 566 of file TGraph2D.cxx.

Paint()

void TGraph2D::Paint ( Option_t *  option = "" )

virtual

Paints this 2D graph with its current attributes.

Reimplemented from TObject.

Definition at line 1366 of file TGraph2D.cxx.

Print()

void TGraph2D::Print ( Option_t *  chopt = "" ) const

virtual

Print 2D graph values.

Reimplemented from TNamed.

Reimplemented in TGraph2DErrors.

Definition at line 1408 of file TGraph2D.cxx.

Project()

TH1 * TGraph2D::Project

(

Option_t *

option = "x"

)

const

Projects a 2-d graph into 1 or 2-d histograms depending on the option parameter.

option may contain a combination of the characters x,y,z:

• option = "x" return the x projection into a TH1D histogram
• option = "y" return the y projection into a TH1D histogram
• option = "xy" return the x versus y projection into a TH2D histogram
• option = "yx" return the y versus x projection into a TH2D histogram

Definition at line 1425 of file TGraph2D.cxx.

RemovePoint()

Int_t TGraph2D::RemovePoint

(

Int_t

ipoint

)

Deletes point number ipoint.

Definition at line 1512 of file TGraph2D.cxx.

SavePrimitive()

void TGraph2D::SavePrimitive ( std::ostream &  out, Option_t *  option = ""  )

virtual

Saves primitive as a C++ statement(s) on output stream out.

Reimplemented from TObject.

Definition at line 1548 of file TGraph2D.cxx.

Scale()

void TGraph2D::Scale ( Double_t  c1 = 1., Option_t *  option = "z"  )

virtual

Multiply the values of a TGraph2D by a constant c1.

If option contains "x" the x values are scaled If option contains "y" the y values are scaled If option contains "z" the z values are scaled If option contains "xyz" all three x, y and z values are scaled

Reimplemented in TGraph2DErrors.

Definition at line 1602 of file TGraph2D.cxx.

Set()

void TGraph2D::Set ( Int_t  n )

virtual

Set number of points in the 2D graph.

Existing coordinates are preserved. New coordinates above fNpoints are preset to 0.

Reimplemented in TGraph2DErrors.

Definition at line 1624 of file TGraph2D.cxx.

SetDirectory()

void TGraph2D::SetDirectory ( TDirectory *  dir )

virtual

By default when an 2D graph is created, it is added to the list of 2D graph objects in the current directory in memory.

This method removes reference to this 2D graph from current directory and add reference to new directory dir. dir can be 0 in which case the 2D graph does not belong to any directory.

Definition at line 1640 of file TGraph2D.cxx.

SetHistogram()

void TGraph2D::SetHistogram ( TH2 *  h )

virtual

Sets the histogram to be filled.

If the 2D graph needs to be save in a TFile the following set should be followed to read it back:

1. Create TGraph2D
2. Call g->SetHistogram(h), and do whatever you need to do
3. Save g and h to the TFile, exit
4. Open the TFile, retrieve g and h
5. Call h->SetDirectory(0)
6. Call g->SetHistogram(h) again
7. Carry on as normal

Definition at line 1661 of file TGraph2D.cxx.

SetMargin()

void TGraph2D::SetMargin

(

Double_t

m = 0.1

)

Sets the extra space (in %) around interpolated area for the 2D histogram.

Definition at line 1674 of file TGraph2D.cxx.

SetMarginBinsContent()

void TGraph2D::SetMarginBinsContent

(

Double_t

z = 0.

)

Sets the histogram bin height for points lying outside the TGraphDelaunay convex hull ie: the bins in the margin.

Definition at line 1694 of file TGraph2D.cxx.

SetMaximum()

void TGraph2D::SetMaximum

(

Double_t

maximum = -1111

)

Set maximum.

Definition at line 1708 of file TGraph2D.cxx.

SetMaxIter()

void TGraph2D::SetMaxIter ( Int_t  n = 100000 )

inline

Definition at line 154 of file TGraph2D.h.

SetMinimum()

void TGraph2D::SetMinimum

(

Double_t

minimum = -1111

)

Set minimum.

Definition at line 1719 of file TGraph2D.cxx.

SetName()

void TGraph2D::SetName ( const char *  name )

virtual

Changes the name of this 2D graph.

Reimplemented from TNamed.

Definition at line 1730 of file TGraph2D.cxx.

SetNameTitle()

void TGraph2D::SetNameTitle ( const char *  name, const char *  title  )

virtual

Change the name and title of this 2D graph.

Reimplemented from TNamed.

Definition at line 1744 of file TGraph2D.cxx.

SetNpx()

void TGraph2D::SetNpx

(

Int_t

npx = 40

)

Sets the number of bins along X used to draw the function.

Definition at line 1758 of file TGraph2D.cxx.

SetNpy()

void TGraph2D::SetNpy

(

Int_t

npx = 40

)

Sets the number of bins along Y used to draw the function.

Definition at line 1780 of file TGraph2D.cxx.

SetPoint()

void TGraph2D::SetPoint ( Int_t  n, Double_t  x, Double_t  y, Double_t  z  )

virtual

Sets point number n.

If n is greater than the current size, the arrays are automatically extended.

Reimplemented in TGraph2DErrors.

Definition at line 1804 of file TGraph2D.cxx.

SetTitle()

void TGraph2D::SetTitle ( const char *  title = "" )

virtual

Sets the 2D graph title.

This method allows to change the global title and the axis' titles of a 2D graph. If g is the 2D graph one can do:

g->SetTitle("Graph title; X axis title; Y axis title; Z axis title");

Reimplemented from TNamed.

Definition at line 1851 of file TGraph2D.cxx.

Member Data Documentation

fDelaunay

TObject* TGraph2D::fDelaunay

protected

! Pointer to Delaunay interpolator object

Definition at line 59 of file TGraph2D.h.

fDirectory

TDirectory* TGraph2D::fDirectory

protected

!Pointer to directory holding this 2D graph

Definition at line 60 of file TGraph2D.h.

fFunctions

TList* TGraph2D::fFunctions

protected

Pointer to list of functions (fits and user)

Definition at line 57 of file TGraph2D.h.

fHistogram

TH2D* TGraph2D::fHistogram

protected

!2D histogram of z values linearly interpolated on the triangles

Definition at line 58 of file TGraph2D.h.

fMargin

Double_t TGraph2D::fMargin

protected

Extra space (in %) around interpolated area for fHistogram.

Definition at line 55 of file TGraph2D.h.

fMaximum

Double_t TGraph2D::fMaximum

protected

Maximum value for plotting along z.

Definition at line 54 of file TGraph2D.h.

fMaxIter

Int_t TGraph2D::fMaxIter

protected

Maximum number of iterations to find Delaunay triangles.

Definition at line 48 of file TGraph2D.h.

fMinimum

Double_t TGraph2D::fMinimum

protected

Minimum value for plotting along z.

Definition at line 53 of file TGraph2D.h.

fNpoints

Int_t TGraph2D::fNpoints

protected

Number of points in the data set.

Definition at line 45 of file TGraph2D.h.

fNpx

Int_t TGraph2D::fNpx

protected

Number of bins along X in fHistogram.

Definition at line 46 of file TGraph2D.h.

fNpy

Int_t TGraph2D::fNpy

protected

Number of bins along Y in fHistogram.

Definition at line 47 of file TGraph2D.h.

fPainter

TVirtualHistPainter* TGraph2D::fPainter

protected

!Pointer to histogram painter

Definition at line 61 of file TGraph2D.h.

fSize

Int_t TGraph2D::fSize

protected

!Real size of fX, fY and fZ

Definition at line 49 of file TGraph2D.h.

fUserHisto

Bool_t TGraph2D::fUserHisto

private

Definition at line 67 of file TGraph2D.h.

fX

Double_t* TGraph2D::fX

protected

[fNpoints]

Definition at line 50 of file TGraph2D.h.

fY

Double_t* TGraph2D::fY

protected

[fNpoints] Data set to be plotted

Definition at line 51 of file TGraph2D.h.

fZ

Double_t* TGraph2D::fZ

protected

[fNpoints]

Definition at line 52 of file TGraph2D.h.

fZout

Double_t TGraph2D::fZout

protected

fHistogram bin height for points lying outside the interpolated area

Definition at line 56 of file TGraph2D.h.

Libraries for TGraph2D:

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The documentation for this class was generated from the following files:

• hist/hist/inc/TGraph2D.h
• hist/hist/src/TGraph2D.cxx