1  # encoding: utf-8
   2  """Utilities for working with data structures like lists, dicts and tuples.
   3  """
   4  
   5  #-----------------------------------------------------------------------------
   6  #  Copyright (C) 2008-2011  The IPython Development Team
   7  #
   8  #  Distributed under the terms of the BSD License.  The full license is in
   9  #  the file COPYING, distributed as part of this software.
  10  #-----------------------------------------------------------------------------
  11  
  12  
  13  def uniq_stable(elems):
  14      """uniq_stable(elems) -> list
  15  
  16      Return from an iterable, a list of all the unique elements in the input,
  17      but maintaining the order in which they first appear.
  18  
  19      Note: All elements in the input must be hashable for this routine
  20      to work, as it internally uses a set for efficiency reasons.
  21      """
  22      seen = set()
  23      return [x for x in elems if x not in seen and not seen.add(x)]
  24  
  25  
  26  def chop(seq, size):
  27      """Chop a sequence into chunks of the given size."""
  28      return [seq[i:i+size] for i in range(0,len(seq),size)]
  29  
  30  
  31