Pyroot Plotting ntuples from different branches of ROOT file

ROOT
1

Hi!

I’m trying to plot different histograms of Photon1 and Photon2 (e.g. pt, eta, phi) but I can’t seem to access them separately when I do mychain.GetEntriesFast(). Does anyone know if this can be done in pyroot?

tree100x.root (121.5 KB)

T2
T2.png692×418 69.6 KB
T
T.png805×677 124 KB

2

Hi,

I do not understand what are you trying to do. The snippets are not coherent! I assume you want two histograms, eta of photon 1 and photon2. Then the code would look like:

myfile = ROOT.TFile("tree100x.root")
events = myfile.T

heta1 = ROOT.TH1D("eta1","eta1",128,-5,5)
heta2 = ROOT.TH1D("eta2","eta2",128,-5,5)

for e in events:
    heta1.Fill(e.photon1.eta)
    heta2.Fill(e.photon1.eta)

heta1.Draw()
heta2.Draw("same")

cheers,
D

3

Hi D,

Thank you for your reply. That is what exactly what I’m trying to do.
Now, when I tried it I get an error:

AttributeErrorTraceback (most recent call last)
<ipython-input-6-cb48b3975ec2> in <module>()
      3 
      4 for e in events:
----> 5     heta1.Fill(e.photon1.eta)
      6     heta2.Fill(e.photon2.eta)
      7 

AttributeError: 'TTree' object has no attribute 'photon1'

Seems like a simple problem but I hope experts could help furthermore.

cheers,
UP

4

Could you add the output of the tree.Print() command?

5

Hi Graipher,

Here it is.

treeprint