I’ve written a python script, which is merging histograms from root files and than putting them together in a canvas to compare them. I save the canvas in a .eps file. With a similar c++ code this works, but now I don’t get any legends in all of my histograms. My code part for the canvasses looks like this:
for a in array: # in array are all names of my histograms in the root files
hist1 = file1.Get("%s" % a)
hist2 = file2.Get("%s" % a)
scale(hist1) #scale is my own function
scale(hist2) #scale is my own function
hs = THStack("%s" % a,"")
hs.Add(hist1)
hs.Add(hist2)
canvas = TCanvas("%s" % a,"",800,600)
hs.Draw("nostack")
legend = TLegend()
legend.SetBorderSize(0)
legend.SetFillColor(0)
legend.AddEntry(hist1, "hist1", "l")
legend.AddEntry(hist2, "hist2", "l")
legend.Draw()
hs.GetYaxis().SetTitle("Entries")
hs.GetYaxis().SetTitleOffset(1.6)
canvas.SaveAs("%s_comparison.eps" % a)
Is it right, that TLegend() ‘finds’ the best place for the legend? Or do I have to give him the x1/2 and y1/2 coordinates? Because that would be a bit problematic, because the position would be different for every canvas. Everything is working fine, I just don’t get any legends…
So where did I miss something? I appreciate any tips or help solving this problem
Yes you can create a TLegend without specifying its position and it will be drawn.
Like in the following example:
{
auto c1 = new TCanvas("c1","c1",600,500);
auto h1 = new TH1F("h1","TLegend Example",200,-10,10);
h1->FillRandom("gaus",30000);
h1->SetFillColor(kGreen);
h1->SetFillStyle(3003);
auto leg = new TLegend();
leg->AddEntry(h1,"Histogram h1","f");
h1->GetListOfFunctions()->Add(leg);
h1->Draw();
}
Can you try this example with the ROOT version you have ? you should get the following picture:
Yes. The Problem is I’ve got over 100 histograms, and in every single one I need to have another position. So I have to find a solution to do that, but I’ve got an idea for that
Now I’ve changed my code from the first time to this:
for a in array: # in array are all names of my histograms in the root files
hist1 = file1.Get("%s" % a)
hist2 = file2.Get("%s" % a)
scale(hist1) #scale is my own function
scale(hist2) #scale is my own function
hs = THStack("%s" % a,"")
hs.Add(hist1)
hs.Add(hist2)
canvas = TCanvas("%s" % a,"",800,600)
hs.Draw("nostack")
legend = TLegend(0.7,0.7,0.9,0.9)
legend.SetBorderSize(0)
legend.SetFillColor(0)
legend.AddEntry(hist1, "hist1", "l")
legend.AddEntry(hist2, "hist2", "l")
legend.Draw()
hs.GetXaxis().SetTitle("bljetnumber")
hs.GetYaxis().SetTitle("Entries")
hs.GetYaxis().SetTitleOffset(1.6)
canvas.SaveAs("%s_comparison.eps" % a)
I think the problem is the eps file I’m saving my canvas in. When I save it in .jpg the legend is there.
But the legend is always in the left corner, like on the histogram above (which is a eps converted to a jpg to upload it here)
I have no problem generating the eps file with the following macro:
{
auto c1 = new TCanvas("c1","c1",600,500);
auto h1 = new TH1F("h1","TLegend Example",200,-10,10);
h1->FillRandom("gaus",30000);
h1->SetFillColor(kGreen);
h1->SetFillStyle(3003);
auto leg = new TLegend(0.3,0.3,0.6,0.6);
leg->SetBorderSize(0);
leg->SetFillColor(0);
leg->AddEntry(h1,"Histogram h1","f");
h1->GetListOfFunctions()->Add(leg);
h1->Draw();
c1->Print("leg2.eps");
}
I see it now, too. I really don’t know what happend before. But ńow all legends are in the left corner, so it is “touching” the data…
I’m now using ROOT 6.10, so TLegend() should work
