No y-axis label when using THStack

Newbie
1

I’m following the very simple THStack tutorial: https://root.cern.ch/doc/master/classTHStack.html on v6.20/02, and I’m trying to add in axis labels just for this very simple tutorial as a test because I’ve been running into some problems with my own code when adding in axis labels. When using the code below, the x-axis label appears but the y-axis label does not (I’ve also attached a copy of the output plot). Perhaps it’s an issue with margins and the y-axis is being plotted out of the margin.

{
  THStack *hs = new THStack("hs","");
  TH1F *h1 = new TH1F("h1","test hstack",10,-4,4);
  h1->FillRandom("gaus",20000);
  h1->SetFillColor(kRed);
  hs->Add(h1);
  TH1F *h2 = new TH1F("h2","test hstack",10,-4,4);
  h2->FillRandom("gaus",15000);
  h2->SetFillColor(kBlue);
  hs->Add(h2);
  TH1F *h3 = new TH1F("h3","test hstack",10,-4,4);
  h3->FillRandom("gaus",10000);
  h3->SetFillColor(kGreen);
  hs->Add(h3);
  TCanvas *cs = new TCanvas("cs","cs",10,10,700,900);
  hs->Draw();
  hs->GetXaxis()->SetTitle("X-AXIS");
  hs->GetYaxis()->SetTitle("Y-AXIS");
  cs->Modified();
}

Also if someone could inform me of the differences between gPad->Update() and gPad->Modified(), I couldn’t really find a clear explanation in the documentation.

THStackAxisLabels.pdf (13.5 KB)

2

Try:
THStack *hs = new THStack("hs", "global title if any;x-axis name if any;y-axis name if any;z-axis name if any");

Right before “hs->Draw();”, add:
gPad->SetLeftMargin(0.15);

Use:
gPad->Modified(); gPad->Update(); // make sure it's really (re)drawn