hist045_Graphics_highlight_ntuple.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)
{
   Long64_t nev = nt->GetSelectedRows();
   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));
      g->SetBit(kCannotPick);
      g->SetMarkerStyle(25);
      g->SetMarkerColor(histo->GetLineColor());
      list->Add(g);
   }
 
   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;
   Canvas2->cd();
   gcommon->Draw("AP");
   // 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");
   Canvas2->Update();
   if (savepad)
      savepad->cd();
}
 
void hist045_Graphics_highlight_ntuple()
{
   auto dir = gROOT->GetTutorialDir();
   dir.Append("/hsimple.C");
   dir.ReplaceAll("/./", "/");
   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->HighlightConnect("Highlight3(TVirtualPad*,TObject*,Int_t,Int_t)");
   Canvas1->Divide(1, 2);
 
   TCanvas *Canvas2 = new TCanvas("Canvas2", "Canvas2", 705, 0, 500, 500);
 
   // Case1, histo1, pz distribution
   Canvas1->cd(1);
   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");
   info1->SetTextColor(histo1->GetLineColor());
   info1->SetBit(kCannotPick);
   info1->Draw();
 
   // Case2, histo2, px*py*pz distribution
   Canvas1->cd(2);
   ntuple->Draw("(px*py*pz)>>histo2(100, -50.0, 50.0)", cut);
   auto histo2 = (TH1F *)gPad->FindObject("histo2");
   histo2->SetLineColor(kGreen + 2);
   auto info2 = new TText(10.0, histo2->GetMaximum() * 0.6, info1->GetTitle());
   info2->SetTextColor(histo2->GetLineColor());
   info2->SetBit(kCannotPick);
   info2->Draw();
   Canvas1->Update();
 
   // set highlight after first drawing completed
   histo1->SetHighlight();
   histo2->SetHighlight();
 
   // Common graph (all entries, all histo bins)
   Canvas2->cd();
   ntuple->Draw("px:py", cut);
   auto gcommon = (TGraph *)gPad->FindObject("Graph");
   gcommon->SetBit(kCanDelete, kFALSE); // will be redraw
   auto htemp = (TH2F *)gPad->FindObject("htemp");
   gcommon->SetTitle(htemp->GetTitle());
   gcommon->GetXaxis()->SetTitle(htemp->GetXaxis()->GetTitle());
   gcommon->GetYaxis()->SetTitle(htemp->GetYaxis()->GetTitle());
   gcommon->Draw("AP");
 
   // Must be last
   ntuple->Draw("px:py:pz", cut, "goff");
   list1 = InitGraphs(ntuple, histo1, true);
   list2 = InitGraphs(ntuple, histo2, false);
}

Date

March 2018

Author

Jan Musinsky

Definition in file hist045_Graphics_highlight_ntuple.C.