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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 different selections. Moving the mouse over the two 1D representation display the on 2D plot the events contributing to the highlighted bin.

TList *list1 = nullptr, *list2 = nullptr;
TList *InitGraphs(TNtuple *nt, TH1F *histo, Bool_t is_top)
Double_t *px = nt->GetV1();
Double_t *py = nt->GetV2();
Double_t *pz = nt->GetV3();
auto list = new TList();
Int_t nbins = histo->GetNbinsX();
for (Int_t bin = 0; bin < nbins; bin++) {
auto g = new TGraph();
g->SetName(TString::Format("g%sbin_%d", histo->GetName(), bin+1));
for (Long64_t ie = 0; ie < nev; ie++) {
Double_t value = is_top ? pz[ie] : px[ie]*py[ie]*pz[ie];
Int_t bin = histo->FindBin(value) - 1;
auto g = dynamic_cast<TGraph *>(list->At(bin));
if (g) g->SetPoint(g->GetN(), py[ie], px[ie]);
return list;
void Highlight3(TVirtualPad *pad, TObject *obj, Int_t xhb, Int_t yhb)
auto histo = dynamic_cast<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 = nullptr;
if (!strcmp(histo->GetName(), "histo1"))
list = list1;
else if (!strcmp(histo->GetName(), "histo2"))
list = list2;
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)
if (savepad) savepad->cd();
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());
// set highlight after first drawing completed
// 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");
list1 = InitGraphs(ntuple, histo1, true);
list2 = InitGraphs(ntuple, histo2, false);
#define g(i)
Definition RSha256.hxx:105
bool Bool_t
Definition RtypesCore.h:63
int Int_t
Definition RtypesCore.h:45
constexpr Bool_t kFALSE
Definition RtypesCore.h:101
double Double_t
Definition RtypesCore.h:59
long long Long64_t
Definition RtypesCore.h:80
@ kGreen
Definition Rtypes.h:66
Option_t Option_t TPoint TPoint const char GetTextMagnitude GetFillStyle GetLineColor GetLineWidth GetMarkerStyle GetTextAlign GetTextColor GetTextSize void value
#define gInterpreter
@ kCanDelete
Definition TObject.h:367
@ kCannotPick
Definition TObject.h:372
#define gROOT
Definition TROOT.h:407
#define gPad
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:1632
TVirtualPad * cd(Int_t subpadnumber=0) override
Set current canvas & pad.
Definition TCanvas.cxx:719
void Update() override
Update canvas pad buffers.
Definition TCanvas.cxx:2478
A ROOT file is an on-disk file, usually with extension .root, that stores objects in a file-system-li...
Definition TFile.h:53
A TGraph is an object made of two arrays X and Y with npoints each.
Definition TGraph.h:41
virtual void SetPoint(Int_t i, Double_t x, Double_t y)
Set x and y values for point number i.
Definition TGraph.cxx:2325
void Draw(Option_t *chopt="") override
Draw this graph with its current attributes.
Definition TGraph.cxx:814
TAxis * GetXaxis() const
Get x axis of the graph.
Definition TGraph.cxx:1549
TAxis * GetYaxis() const
Get y axis of the graph.
Definition TGraph.cxx:1558
TObject * FindObject(const char *name) const override
Search object named name in the list of functions.
Definition TGraph.cxx:1094
void SetTitle(const char *title="") override
Change (i.e.
Definition TGraph.cxx:2380
1-D histogram with a float per channel (see TH1 documentation)
Definition TH1.h:622
virtual Int_t GetNbinsX() const
Definition TH1.h:297
virtual Bool_t IsHighlight() const
Definition TH1.h:338
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:3672
2-D histogram with a float per channel (see TH1 documentation)
Definition TH2.h:307
A doubly linked list.
Definition TList.h:38
TObject * At(Int_t idx) const override
Returns the object at position idx. Returns 0 if idx is out of range.
Definition TList.cxx:355
virtual void SetTitle(const char *title="")
Set the title of the TNamed.
Definition TNamed.cxx:164
const char * GetName() const override
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:41
void SetBit(UInt_t f, Bool_t set)
Set or unset the user status bits as specified in f.
Definition TObject.cxx:780
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:1196
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:2647
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:2378
Base class for several text objects.
Definition TText.h:22
virtual Long64_t GetSelectedRows()
Definition TTree.h:513
void Draw(Option_t *opt) override
Default Draw method for all objects.
Definition TTree.h:431
virtual Double_t * GetV3()
Definition TTree.h:540
virtual Double_t * GetV1()
Definition TTree.h:536
virtual Double_t * GetV2()
Definition TTree.h:538
TVirtualPad is an abstract base class for the Pad and Canvas classes.
Definition TVirtualPad.h:51
virtual TVirtualPad * cd(Int_t subpadnumber=0)=0
March 2018
Jan Musinsky

Definition in file hlHisto3.C.