Unsupported Operand Type

ROOT
1

Hi, I’ve got this code which takes a number of .root files, each with 3 different TH1F histograms. It adds up all the root files, and outputs a .root file with the 3 different summed histograms. Here is the type error:

      2     for filename in files[1:]:
      3         f = TFile(filename)
----> 4         p_loss += TH1F(f.Get("PlossHisto"))
      5         e_loss += TH1F(f.Get("ElossHisto"))
      6         p_hits += TH1F(f.Get("PhitsHisto"))

TypeError: unsupported operand type(s) for +=: 'PyROOT_NoneType' and 'TH1F'

Now this is fair enough, except as shown below I’ve defined p_loss, e_loss and p_hits as type TH1F:

[code] #create clones of first histograms
#these are now the total histograms we add to
p_loss = TH1F.Clone(plosshis)
e_loss = TH1F.Clone(ehitshis)
p_hits = TH1F.Clone(phitshis)

if len(files) > 1:
    for filename in files[1:]:
        f = TFile(filename)
        p_loss += TH1F(f.Get("PlossHisto"))
        e_loss += TH1F(f.Get("ElossHisto"))
        p_hits += TH1F(f.Get("PhitsHisto"))
        f.Close()

[/code]

The operator ‘+=’ will work for two TH1F, but it appears the p_loss, e_loss and p_hits histograms lose their TH1F type and I don’t know why. Any insight offered would be greatly appreciated.

2

Can you explicitly check that the histograms you are Cloning from are valid, and that the histograms you get from the files are also valid?

I think if you TFile::Get an object with a name that doesn’t exist, you get a NoneType, so maybe your histogram names are incorrect, or maybe your filenames are incorrect (and thus opened as zombies).

Jean-François

3

Hi,

what Jean-François said, but with a small addition. You get NoneType if an object does not exist, but you get PyROOT_NoneType if an object initially existed, and then got deleted on the C++ side. Likely your histograms have the same name?

Cheers,
Wim