Draw X-Axis with specific values

ROOT
, , , ,
2

This is a slight modification of a macro found on this forum some time ago, so all credit goes to the original author, couet:

void aa()
{
  TGraph *g1 = new TGraph("aa.txt");
  g1->SetMarkerStyle(20);
  g1->SetMarkerColorAlpha(kBlue, 0.35);
  g1->GetYaxis()->SetTitle("Y axis");
  g1->GetXaxis()->SetTitle("X axis");
  g1->SetMarkerSize(1);

  g1->Draw("APL");
  g1->GetXaxis()->SetLabelSize(0);
  g1->GetXaxis()->SetTickLength(0);

  Int_t i,n;
  Double_t x,y;
  TLatex *t;
  TLine *tick;
  TLine *grid;
  double ymin = g1->GetHistogram()->GetMinimum();
  double ymax = g1->GetHistogram()->GetMaximum();
  double dy = (ymax-ymin);
  n = g1->GetN();
  for (i=0; i<n; i++) {
    g1->GetPoint(i,x,y);
    t = new TLatex(x, ymin-0.03*dy, Form("%4.3f",x));
    t->SetTextSize(0.03);
    t->SetTextFont(42);
    t->SetTextAlign(21);
    t->Draw();
    tick = new TLine(x,ymin,x,ymin+0.03*dy);
    tick->Draw();
    grid = new TLine(x,ymin,x,y);
    grid->SetLineStyle(3);
    grid->Draw();
  }
}

You can leave out the “grid” lines if not needed.
Edit - Original post: