I am seeing some issues when plotting the contents of a TTree using the Draw functions and assigning it weights. I have attached the TTree in question.
Using ROOT 6.00.02, I plot the value 1 with weight event_weight and look at its integral. There are 125 (non-zero weight) entries and the integral is 1663. The histogram is attached as rootgood.pdf.
Then I do the exact same thing using ROOT 6.02.10 (also tried 6.04.00) . Now the event count is 250 and the integral is 3327. The histogram is attached as rootbad.pdf.
Any idea why I see this difference? The tests were done on lxplus using ROOT from AFS. rootbad.pdf (13.4 KB) rootgood.pdf (13.5 KB) test.root (5.59 KB)
This problem, appearing only when the histogram buffer is used with histogram filled with weights different than one, has been fixed in 6.02, 6.04 patches and master.
See also comments and git commit links in sft.its.cern.ch/jira/browse/ROOT-7328
Hi,
I’ve just installed ROOT 6.04 and still experience this issue…
It might be linked to [url=https://root-forum.cern.ch/t/histogram-created-by-ttree-draw-behaves-erroneously/19223/5 which is also supposedly fixed, but does’t seem to be.