no way to compare when less than two revisions

Differences

This shows you the differences between two versions of the page.

@@ Line 1: / Line 1: @@
+====== How to overlay tow histograms and draw both stats boxes ======
+void myfunction()
+{
+  ...
+  TCanvas *c = new TCanvas(...)
+  TH1D *h1 = new TH1D(...) ; // histo 1
+  TH1D *h2 = new TH1D(...) ; // histo 2
+  // set stats options (show histo title, nEntries, mean, rms)
+  gStyle->SetOptStat(1111);
+  // draw histo 1
+  h1->Draw(); // draw histo and stats box on default position
+  // get stats box
+  gPad->Update();
+  TPaveStats *statsbox = (TPaveStats*)gPad->GetPrimitive("stats");
+  // get (default) y position of stats box (histo h1)
+  double y1 = statsbox->GetY1NDC(); // (lower) y start position of stats box
+  double y2 = statsbox->GetY2NDC(); // (upper) y start position of stats box
+  // set new position of stats box (histo h1)
+  double newy1 = 2 * y1 - y2;   // new (lower) y start position of stats box
+  double newy2 = y1;            // new (upper) y start position of stats box
+  statsbox->SetY1NDC(newy1);    //set new y start position
+  statsbox->SetY2NDC(newy2);    //set new y end position
+  // draw histo 2
+  h2->Draw("sames"); // draw stats box on default position
+  // Draw options:
+  // "same"  : draw histogram on same canvas, do not redraw stats box
+  // "sames" : draw histogram on same canvas, draw stats box (in default position)
+ ...
+}

LHCb Wiki Pages