read_hist_ntuple.py

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#! /usr/bin/env python
# Copyright (C) 2002-2026 CERN for the benefit of the ATLAS collaboration
 
from ROOT import TFile
print(":" * 80)
print("::: ntuple...")
f1 = TFile.Open("ntuple.root","READ")
t = f1.Get("trees/tree1")
print(":: entries:", t.GetEntries())
print(":: branches:", [b.GetName() for b in t.GetListOfBranches()])
for i in range(t.GetEntries()):
    if t.GetEntry(i) <= 0:
        print("** error reading entry [%i]" % (i,))
        break
    print(":: entry [%i]..." % (i,))
    print("::  run:", t.run)
    print("::  size:", t.size)
    print("::  rundata:", list(t.rundata))
print(":: done.")
 
print(":" * 80)
print("::: histogram...")
f2 = TFile.Open("hist.root", "READ")
h1 = f2.Get("simple1D/h1")
print(":: entries:", h1.GetEntries())
h1.Draw()
print(":: done.")
 
print("::: bye.")