Std::ostream in python

[rauser]

Dear ROOT and python experts,

I’m trying to call SavePrimitive() on a THStack in python, which requires a parameter for the output stream. Could you point me to how I could achieve this. I tried sys.stdout, which didn’t work.

Thanks, Johann

[bellenot]

I guess @etejedor can most probably give you some hints

[etejedor]

Hi Johann,

You can try with ROOT.std.cout or any other ostream that you create from Python.

Cheers,
Enric

[rauser]

Hi Enric,

thanks for the fast reply! Could you maybe give me an example on how to use this? For me this basic example results in an error:

import ROOT
stack = ROOT.THStack("test","test")
stack.SavePrimitive(ROOT.std.cout)

The error message is:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/cvmfs/sft.cern.ch/lcg/app/releases/ROOT/6.16.00/x86_64-centos7-gcc48-opt/lib/cppyy.py", line 177, in __getattr__
    raise AttributeError(str(e))
AttributeError: requested class 'cout' does not exist

Thanks,

Johann

[rauser]

A colleague just pointed me to the solution, which is using ROOT.cout. He found it on: Using ROOT::Fit::FitResult::Print method with pyroot: Ofstream

Cheers, Johann