I am trying to draw a tree containing string entries in descending order of the bin contents. This sometimes works using the LabelsOption(">",“X”), and sometimes it does not. I am attaching a script and a root file showing how this work only sometimes (for one of the trees in this case).
@couet I would be very grateful for any suggestion on how to draw both trees (not just one) in descending order of the bin content. Without the LabelsOption(">",“X”), both trees are drawn randomly, with random (not ordered) been contents.
{
TFile *f1 = TFile::Open("two_trees_descending.root");
gROOT->cd();
TTree *tree_vertex; f1->GetObject("tree_vertex", tree_vertex);
tree_vertex->Draw("vol");
TH1 *htemp2 = (TH1*)(gPad->GetPrimitive("htemp")->Clone("htemp2"));
htemp2->Print("all"); // original "unsorted" fSumw contents
htemp2->LabelsOption(">", "X");
htemp2->Print("all"); // "sorted" fSumw contents
htemp2->Draw("HIST");
htemp2->Print("all"); // still "sorted" fSumw contents
gPad->Update(); // abracadabra (definitely black magic)
// original "unsorted" fSumw contents RESTORED but labels are "sorted"
htemp2->Print("all");
}
This bug exists in ROOT 6 and 5.
Actually, in ROOT 5, additionally, the fSumw contents entries printed by the first 3 “Print” statements above (1 x “unsorted” and 2 x “sorted”) have doubled values (“Total sum” = 2 * “Entries”) so maybe the problem originates in TTree Draw (the very last “Print” statement shows values for which “Total sum” = “Entries”).
If I add “htemp2->BufferEmpty(1);” right after the “Clone” and before the first “Print” then the histogram bins remain “sorted” also after “gPad->Update();”, but in ROOT 5 the fSumw contents entries remain doubled.
The “tree_vertex” tree has 612 entries so a very brutal fix, which works in ROOT 6 and 5, is to add right in the beginning e.g.: TH1::SetDefaultBufferSize(500); // must be < 612