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Reference Guide
hlHisto3.C File Reference

Detailed Description

This tutorial demonstrates how the highlight mechanism can be used on a ntuple.

The ntuple in hsimple.root is drawn with three differents selection. Moving the mouse ove the two 1D representation display the on 2D plot the events contributing to the highlighted bin.

TList *list1 = 0;
TList *list2 = 0;
void InitGraphs(TNtuple *nt, TH1F *histo);
void Highlight3(TVirtualPad *pad, TObject *obj, Int_t xhb, Int_t yhb);
void hlHisto3()
auto dir = gROOT->GetTutorialDir();
if (!gInterpreter->IsLoaded(dir.Data())) gInterpreter->LoadMacro(dir.Data());
auto file = (TFile*)gROOT->ProcessLineFast("hsimple(1)");
if (!file) return;
TNtuple *ntuple;
file->GetObject("ntuple", ntuple);
if (!ntuple) return;
const char *cut = "pz > 3.0";
TCanvas *Canvas1 = new TCanvas("Canvas1", "Canvas1", 0, 0, 700, 500);
Canvas1->Divide(1, 2);
TCanvas *Canvas2 = new TCanvas("Canvas2", "Canvas2", 705, 0, 500, 500);
// Case1, histo1, pz distribution
ntuple->Draw("pz>>histo1(100, 2.0, 12.0)", cut);
auto histo1 = (TH1F *)gPad->FindObject("histo1");
auto info1 = new TText(7.0, histo1->GetMaximum()*0.6,
"please move the mouse over the frame");
// Case2, histo2, px*py*pz distribution
ntuple->Draw("(px*py*pz)>>histo2(100, -50.0, 50.0)", cut);
auto histo2 = (TH1F *)gPad->FindObject("histo2");
auto info2 = new TText(10.0, histo2->GetMaximum()*0.6, info1->GetTitle());
// Common graph (all entries, all histo bins)
ntuple->Draw("px:py", cut);
auto gcommon = (TGraph *)gPad->FindObject("Graph");
gcommon->SetBit(kCanDelete, kFALSE); // will be redraw
auto htemp = (TH2F *)gPad->FindObject("htemp");
// Must be last
ntuple->Draw("px:py:pz", cut, "goff");
histo1->SetUniqueID(1); // mark as case1
histo2->SetUniqueID(2); // mark as case2
InitGraphs(ntuple, histo1);
InitGraphs(ntuple, histo2);
void InitGraphs(TNtuple *nt, TH1F *histo)
Double_t *px = nt->GetV1();
Double_t *py = nt->GetV2();
Double_t *pz = nt->GetV3();
auto list = new TList();
if (histo->GetUniqueID() == 1) list1 = list;
else if (histo->GetUniqueID() == 2) list2 = list;
else return;
Int_t nbins = histo->GetNbinsX();
Int_t bin;
for (bin = 0; bin < nbins; bin++) {
g = new TGraph();
g->SetName(TString::Format("g%sbin_%d", histo->GetName(), bin+1));
Double_t value = 0.0;
for (Long64_t ie = 0; ie < nev; ie++) {
if (histo->GetUniqueID() == 1) value = pz[ie];
if (histo->GetUniqueID() == 2) value = px[ie]*py[ie]*pz[ie];
bin = histo->FindBin(value) - 1;
g = (TGraph *)list->At(bin);
if (!g) continue; // under/overflow
g->SetPoint(g->GetN(), py[ie], px[ie]); // reverse as px:py
void Highlight3(TVirtualPad *pad, TObject *obj, Int_t xhb, Int_t yhb)
auto histo = (TH1F *)obj;
if(!histo) return;
TCanvas *Canvas2 = (TCanvas *)gROOT->GetListOfCanvases()->FindObject("Canvas2");
if (!Canvas2) return;
TGraph *gcommon = (TGraph *)Canvas2->FindObject("Graph");
if (!gcommon) return;
TList *list = 0;
if (histo->GetUniqueID() == 1) list = list1; // case1
else if (histo->GetUniqueID() == 2) list = list2; // case2
if (!list) return;
TGraph *g = (TGraph *)list->At(xhb);
if (!g) return;
TVirtualPad *savepad = gPad;
//gcommon->SetTitle(TString::Format("%d / %d", g->GetN(), gcommon->GetN()));
if (histo->IsHighlight()) // don't draw g after highlight disabled
if (g->GetN() > 0) g->Draw("P");
#define g(i)
Definition: RSha256.hxx:105
int Int_t
Definition: RtypesCore.h:45
const Bool_t kFALSE
Definition: RtypesCore.h:92
double Double_t
Definition: RtypesCore.h:59
long long Long64_t
Definition: RtypesCore.h:73
@ kGreen
Definition: Rtypes.h:66
#define gInterpreter
Definition: TInterpreter.h:562
@ kCanDelete
Definition: TObject.h:354
@ kCannotPick
Definition: TObject.h:359
#define gROOT
Definition: TROOT.h:406
#define gPad
Definition: TVirtualPad.h:287
virtual Color_t GetLineColor() const
Return the line color.
Definition: TAttLine.h:33
The Canvas class.
Definition: TCanvas.h:23
virtual void HighlightConnect(const char *slot)
This is "simplification" for function TCanvas::Connect with Highlighted signal for specific slot.
Definition: TCanvas.cxx:1633
TVirtualPad * cd(Int_t subpadnumber=0) override
Set current canvas & pad.
Definition: TCanvas.cxx:708
void Update() override
Update canvas pad buffers.
Definition: TCanvas.cxx:2504
A ROOT file is a suite of consecutive data records (TKey instances) with a well defined format.
Definition: TFile.h:54
A TGraph is an object made of two arrays X and Y with npoints each.
Definition: TGraph.h:41
virtual void Draw(Option_t *chopt="")
Draw this graph with its current attributes.
Definition: TGraph.cxx:769
1-D histogram with a float per channel (see TH1 documentation)}
Definition: TH1.h:575
virtual Int_t GetNbinsX() const
Definition: TH1.h:296
virtual Bool_t IsHighlight() const
Definition: TH1.h:334
virtual Int_t FindBin(Double_t x, Double_t y=0, Double_t z=0)
Return Global bin number corresponding to x,y,z.
Definition: TH1.cxx:3680
2-D histogram with a float per channel (see TH1 documentation)}
Definition: TH2.h:251
A doubly linked list.
Definition: TList.h:44
virtual TObject * At(Int_t idx) const
Returns the object at position idx. Returns 0 if idx is out of range.
Definition: TList.cxx:357
virtual const char * GetName() const
Returns name of object.
Definition: TNamed.h:47
A simple TTree restricted to a list of float variables only.
Definition: TNtuple.h:28
Mother of all ROOT objects.
Definition: TObject.h:37
virtual UInt_t GetUniqueID() const
Return the unique object id.
Definition: TObject.cxx:377
void Divide(Int_t nx=1, Int_t ny=1, Float_t xmargin=0.01, Float_t ymargin=0.01, Int_t color=0) override
Automatic pad generation by division.
Definition: TPad.cxx:1177
TObject * FindObject(const char *name) const override
Search if object named name is inside this pad or in pads inside this pad.
Definition: TPad.cxx:2625
static TString Format(const char *fmt,...)
Static method which formats a string using a printf style format descriptor and return a TString.
Definition: TString.cxx:2331
Base class for several text objects.
Definition: TText.h:22
virtual Long64_t GetSelectedRows()
Definition: TTree.h:509
virtual Double_t * GetV3()
Definition: TTree.h:536
virtual Double_t * GetV1()
Definition: TTree.h:532
virtual void Draw(Option_t *opt)
Default Draw method for all objects.
Definition: TTree.h:428
virtual Double_t * GetV2()
Definition: TTree.h:534
TVirtualPad is an abstract base class for the Pad and Canvas classes.
Definition: TVirtualPad.h:51
virtual TVirtualPad * cd(Int_t subpadnumber=0)=0
Definition: file.py:1
March 2018
Jan Musinsky

Definition in file hlHisto3.C.