How to sort a dictionary by key?

Question

i tried to sort dict by key but no chance. this is my dict :

result={'1':'value1','2':'value2',...}

i'm using Python2.7 and i found this

keys = result.keys()
keys.sort()

but this is not what i expected, i have an unsorted dict.

score 12 · Accepted Answer · answered Mar 25 '13 at 11:44

12

Standard Python dictionaries are inherently unordered. However, you could use collections.OrderedDict. It preserves the insertion order, so all you have to do is add the key/value pairs in the desired order:

In [4]: collections.OrderedDict(sorted(result.items()))
Out[4]: OrderedDict([('1', 'value1'), ('2', 'value2')])

answered Mar 25 '13 at 11:44

NPE

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what if i had 1000 couple of (key, value) ?? – Imoum Mar 25 '13 at 12:56
what to do if I have to sort the `OrderedDict([('1', 'value1'), ('2', 'value2')])` in reverse order by `value*` – Chitrank Dixit Jul 08 '16 at 10:24

Jakub M. · Answer 2 · 2013-03-25T11:56:27.503

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sorted(result.iteritems(), key=lambda key_value: key_value[0])

This will output sorted results, but the dictionary will remain unsorted. If you want to maintain ordering of a dictionary, use OrderedDict

Actually, if you sort by key you could skip the key=... part, because then the iterated items are sorted first by key and later by value (what NPE uses in his answer)

edited Mar 25 '13 at 11:56

answered Mar 25 '13 at 11:44

Jakub M.

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I'd personally go for `key=lambda (key,val): val)` which is also correct, but IMHO also more explicit – Jon Clements Mar 25 '13 at 11:48
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@JonClements that's deprecated in python 3 so the current approach is better – jamylak Mar 25 '13 at 11:50
@jamylak: why is that deprecated? Any references? – Jakub M. Mar 25 '13 at 11:51
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@JakubM. http://www.python.org/dev/peps/pep-3113/ – RoadieRich Mar 25 '13 at 11:53
@JakubM. it was to do with unpacking references - the 3.x series disallowed such constructs as def f(somearg, (nextarg, otherarg)) – Jon Clements Mar 25 '13 at 11:53
Why not just sorted(result.iteritems()) – Stan Bashtavenko Oct 02 '17 at 14:28

score 3 · Answer 3 · answered Mar 25 '13 at 11:44

3

Python dictionaries are unordered (for definition)

You can use OrderedDict instead

answered Mar 25 '13 at 11:44

DonCallisto

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How to sort a dictionary by key?

3 Answers3