Just curious - I thought dict keys would maintain sequence

Frank Millman frank at chagford.com
Mon Mar 18 08:26:19 CET 2013

Hi all

I know that you cannot rely on the order of keys in a dictionary, and I 
am not attempting to do so.

Nevertheless, the following surprised me. A program creates a dictionary 
with a known set of keys. I would have thought that multiple runs of the 
program would return the keys in the same sequence. As you can see, the 
results appear to be totally random.

Just out of interest, I would appreciate an explanation.


Frank Millman

F:\>type test.py
test_list = [
     'ert', 'jhg', 'yer', 'nli', 'vrg',
     'qnh', 'kyh', 'cgj', 'lys', 'vyk',
     'dws', 'fuj', 'ghj', 'puy', 'brc',
     'dhy', 'jkl', 'gfd', 'jtf', 'dfp']
test_dict = dict([(x, None) for x in test_list])

dict_keys(['ghj', 'qnh', 'lys', 'ert', 'jhg', 'dfp', 'vrg', 'dws', 
'jtf', 'puy',
  'yer', 'brc', 'kyh', 'jkl', 'gfd', 'nli', 'fuj', 'dhy', 'cgj', 'vyk'])

dict_keys(['vrg', 'dfp', 'brc', 'yer', 'nli', 'jhg', 'cgj', 'ert', 
'dws', 'gfd',
  'puy', 'vyk', 'ghj', 'jkl', 'jtf', 'kyh', 'qnh', 'fuj', 'dhy', 'lys'])

dict_keys(['yer', 'nli', 'brc', 'fuj', 'cgj', 'dfp', 'dhy', 'vrg', 
'jkl', 'jtf',
  'vyk', 'ghj', 'qnh', 'kyh', 'gfd', 'ert', 'dws', 'jhg', 'lys', 'puy'])

Python version is 3.3.0, win32.

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