old_contents: #!/usr/bin/env python
  
  from rootpy.io import open
  from time import time
  from ROOT import TTreeCache
  import sys
  
  for cached in (False, True):
  
      try:
          f = open("test.root")
      except IOError:
          sys.exit("test.root does not exist. Please run tree_write.py first.")
      tree = f.test
  
      if cached:
          TTreeCache.SetLearnEntries(1)
          tree.SetCacheSize(10000000)
      tree.use_cache(cached)
  
      start_time = time()
      for event in tree:
          event.x
      end_time = time()
      print "%.2fsec to read one branch" % (end_time - start_time)
  
      start_time = time()
      for event in tree:
          event.x
          event.y
      end_time = time()
      print "%.2fsec to read two branches" % (end_time - start_time)
  
      start_time = time()
      for event in tree:
          event.x
          event.y
          event.z
      end_time = time()
      print "%.2fsec to read three branches" % (end_time - start_time)
  
      print "Reading %i bytes in %i transactions" % (f.GetBytesRead(), f.GetReadCalls())
      f.close()
  
new_contents: #!/usr/bin/env python
  
  # this import is required to register the Tree class
  import rootpy.tree
  from rootpy.io import open
  from time import time
  from ROOT import TTreeCache
  import sys
  
  for cached in (False, True):
  
      try:
          f = open("test.root")
      except IOError:
          sys.exit("test.root does not exist. Please run tree_write.py first.")
      tree = f.test
  
      if cached:
          TTreeCache.SetLearnEntries(1)
          tree.SetCacheSize(10000000)
      tree.use_cache(cached)
  
      start_time = time()
      for event in tree:
          event.x
      end_time = time()
      print "%.2fsec to read one branch" % (end_time - start_time)
  
      start_time = time()
      for event in tree:
          event.x
          event.y
      end_time = time()
      print "%.2fsec to read two branches" % (end_time - start_time)
  
      start_time = time()
      for event in tree:
          event.x
          event.y
          event.z
      end_time = time()
      print "%.2fsec to read three branches" % (end_time - start_time)
  
      print "Reading %i bytes in %i transactions" % (f.GetBytesRead(), f.GetReadCalls())
      f.close()
  
subject: fix import