TH2Poly::Draw("text") omitting negative numbers

ROOT
1

Hi,

I run the following code:

from ROOT import TCanvas, TH2Poly, TH2F
from array  import array

c = TCanvas()

# Try with TH2F
h2 = TH2F("h2","",2,0,2,1,0,1)
h2.Fill(0.5,0.5, -1) 
h2.Fill(1.5,0.5,  1)  

h2.Draw("text")
c.Print("test_th2f.png")

# Try with TH2Poly
h3 = TH2Poly()
x1 = [0,1,1,0] # Define one square bin
y1 = [0,0,1,1]
x2 = [1,2,2,1] # Define a second
y2 = [0,0,1,1] 
arr_x1 = array('d',x1)
arr_y1 = array('d',y1)
arr_x2 = array('d',x2)
arr_y2 = array('d',y2)
h3.AddBin(4,arr_x1,arr_y1)
h3.AddBin(4,arr_x2,arr_y2)
h3.Fill(0.5,0.5,-1)
h3.Fill(1.5,0.5, 1)

h3.Draw("text")
c.Print("test_th2poly.png")

But only the text marker corresponding to the positive bin is shown for the TH2Poly. Do you know why? I was expecting behaviour identical to the TH2F case.

25
Screenshot 2019-11-14 at 16.41.25.png698×992 25.3 KB

Thanks in advance,
Dan

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ROOT Version: Multiple [most recently 6.16.00]
Platform: SLC6
Compiler: gcc8

3

For some reason the Minimum of the TH2Poly is 0 .
Try GetMinimum() on it…
If you do:

h2.SetMinimum(-3);

It will work. This needs to be investigated.

4

Confirmed, thank you for the super-quick fix!

5

That’s not fix. It’s a workaround. The fix will come later. I need to understand why negative minimum does not work.

6

Now fixed in ROOT master. Thanks to have seen it.