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Reference Guide
DynamicSlice.C File Reference

Detailed Description

View in nbviewer Open in SWAN Show the slice of a TH2 following the mouse position.

{
// Create a new canvas.
TCanvas* c1 = new TCanvas("c1","Dynamic Slice Example",10,10,700,500);
//create a 2-d histogram, fill and draw it
TH2F *hpxpy = new TH2F("hpxpy","py vs px",40,-4,4,40,-4,4);
hpxpy->SetStats(0);
Double_t px,py;
for (Int_t i = 0; i < 50000; i++) {
gRandom->Rannor(px,py);
hpxpy->Fill(px,py);
}
hpxpy->Draw("col");
//Add a TExec object to the canvas
c1->AddExec("dynamic","DynamicExec()");
}
void DynamicExec()
{
// Example of function called when a mouse event occurs in a pad.
// When moving the mouse in the canvas, a second canvas shows the
// projection along X of the bin corresponding to the Y position
// of the mouse. The resulting histogram is fitted with a gaussian.
// A "dynamic" line shows the current bin position in Y.
// This more elaborated example can be used as a starting point
// to develop more powerful interactive applications exploiting Cling
// as a development engine.
TObject *select = gPad->GetSelected();
if(!select) return;
if (!select->InheritsFrom(TH2::Class())) {gPad->SetUniqueID(0); return;}
TH2 *h = (TH2*)select;
gPad->GetCanvas()->FeedbackMode(kTRUE);
//erase old position and draw a line at current position
int pyold = gPad->GetUniqueID();
int px = gPad->GetEventX();
int py = gPad->GetEventY();
float uxmin = gPad->GetUxmin();
float uxmax = gPad->GetUxmax();
int pxmin = gPad->XtoAbsPixel(uxmin);
int pxmax = gPad->XtoAbsPixel(uxmax);
if(pyold) gVirtualX->DrawLine(pxmin,pyold,pxmax,pyold);
gVirtualX->DrawLine(pxmin,py,pxmax,py);
gPad->SetUniqueID(py);
Float_t upy = gPad->AbsPixeltoY(py);
Float_t y = gPad->PadtoY(upy);
//create or set the new canvas c2
TVirtualPad *padsav = gPad;
TCanvas *c2 = (TCanvas*)gROOT->GetListOfCanvases()->FindObject("c2");
if(c2) delete c2->GetPrimitive("Projection");
else c2 = new TCanvas("c2","Projection Canvas",710,10,700,500);
c2->SetGrid();
c2->cd();
//draw slice corresponding to mouse position
Int_t biny = h->GetYaxis()->FindBin(y);
TH1D *hp = h->ProjectionX("",biny,biny);
hp->SetFillColor(38);
char title[80];
sprintf(title,"Projection of biny=%d",biny);
hp->SetName("Projection");
hp->SetTitle(title);
hp->Fit("gaus","ql");
hp->GetFunction("gaus")->SetLineColor(kRed);
hp->GetFunction("gaus")->SetLineWidth(6);
c2->Update();
padsav->cd();
}
Author
Rene Brun

Definition in file DynamicSlice.C.

TH1::GetFunction
virtual TF1 * GetFunction(const char *name) const
Return pointer to function with name.
Definition: TH1.cxx:8506
kTRUE
const Bool_t kTRUE
Definition: RtypesCore.h:91
gVirtualX
#define gVirtualX
Definition: TVirtualX.h:338
TH2F
2-D histogram with a float per channel (see TH1 documentation)}
Definition: TH2.h:251
TH1D
1-D histogram with a double per channel (see TH1 documentation)}
Definition: TH1.h:615
Float_t
float Float_t
Definition: RtypesCore.h:57
TVirtualPad::cd
virtual TVirtualPad * cd(Int_t subpadnumber=0)=0
Int_t
int Int_t
Definition: RtypesCore.h:45
TH1::SetName
virtual void SetName(const char *name)
Change the name of this histogram.
Definition: TH1.cxx:8415
TObject::InheritsFrom
virtual Bool_t InheritsFrom(const char *classname) const
Returns kTRUE if object inherits from class "classname".
Definition: TObject.cxx:445
TH1::SetTitle
virtual void SetTitle(const char *title)
See GetStatOverflows for more information.
Definition: TH1.cxx:6344
TRandom::Rannor
virtual void Rannor(Float_t &a, Float_t &b)
Return 2 numbers distributed following a gaussian with mean=0 and sigma=1.
Definition: TRandom.cxx:489
h
#define h(i)
Definition: RSha256.hxx:124
DynamicSlice
Definition: DynamicSlice.py:1
gRandom
R__EXTERN TRandom * gRandom
Definition: TRandom.h:62
TH2
Definition: TH2.h:30
y
Double_t y[n]
Definition: legend1.C:17
kRed
@ kRed
Definition: Rtypes.h:66
TH1::SetStats
virtual void SetStats(Bool_t stats=kTRUE)
Set statistics option on/off.
Definition: TH1.cxx:8445
TH2::Fill
Int_t Fill(Double_t)
Invalid Fill method.
Definition: TH2.cxx:294
Double_t
double Double_t
Definition: RtypesCore.h:59
TVirtualPad
Definition: TVirtualPad.h:50
TCanvas
Definition: TCanvas.h:23
TObject
Definition: TObject.h:37
c2
return c2
Definition: legend2.C:14
gPad
#define gPad
Definition: TVirtualPad.h:287
TH1::Fit
virtual TFitResultPtr Fit(const char *formula, Option_t *option="", Option_t *goption="", Double_t xmin=0, Double_t xmax=0)
Fit histogram with function fname.
Definition: TH1.cxx:3807
Class
void Class()
Definition: Class.C:29
gROOT
#define gROOT
Definition: TROOT.h:406
TH1::Draw
virtual void Draw(Option_t *option="")
Draw this histogram with options.
Definition: TH1.cxx:2997
c1
return c1
Definition: legend1.C:41