65

I'm trying to sort OrderedDict in OrderedDict by 'depth' key. Is there any solution to sort that Dictionary ? 

OrderedDict([
  (2, OrderedDict([
    ('depth', 0),  
    ('height', 51), 
    ('width', 51),   
    ('id', 100)
  ])), 
  (1, OrderedDict([
    ('depth', 2),  
    ('height', 51), 
    ('width', 51),  
    ('id', 55)
  ])), 
  (0, OrderedDict([
    ('depth', 1),  
    ('height', 51), 
    ('width', 51),  
    ('id', 48)
  ])),
])

Sorted dict should look like this:

OrderedDict([
  (2, OrderedDict([
    ('depth', 0),  
    ('height', 51), 
    ('width', 51),   
    ('id', 100)
  ])), 
  (0, OrderedDict([
    ('depth', 1),  
    ('height', 51), 
    ('width', 51),  
    ('id', 48)
  ])),
  (1, OrderedDict([
    ('depth', 2),  
    ('height', 51), 
    ('width', 51),  
    ('id', 55)
  ])), 
])

Any idea how to get it?

martineau
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Damian Gądziak
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3 Answers3

117

You'll have to create a new one since OrderedDict is sorted by insertion order.

In your case the code would look like this:

foo = OrderedDict(sorted(foo.items(), key=lambda x: x[1]['depth']))

See http://docs.python.org/dev/library/collections.html#ordereddict-examples-and-recipes for more examples.

Note for Python 2 you will need to use .iteritems() instead of .items().

Gulzar
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ThiefMaster
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    This will cause an exception if any dict doesn't have 'depth' as a key. This might be desired. If it isn't, you can assume a default key by using "get". – TomOnTime Sep 04 '13 at 10:17
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    Note that `[1]` here refers to foo's values, as opposed to its keys, which would be `[0]` – e18r Mar 29 '16 at 17:14
20
>>> OrderedDict(sorted(od.items(), key=lambda item: item[1]['depth']))
Raymond Hettinger
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5

Sometimes you might want to keep the initial dictionary and not create a new one.

In that case you could do the following:

temp = sorted(list(foo.items()), key=lambda x: x[1]['depth'])
foo.clear()
foo.update(temp)
johnson
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  • I am curious, can you give an example when one would want to clear and update an existing dictionary, instead of re-assigning it? – Ataxias Dec 31 '21 at 02:37
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    When you are handling dicts that might have been subclassed – johnson Jan 01 '22 at 09:11
  • @johnson Good point. A real world example for those not convinced: I recently ran across a situation using ruamel.yaml, where if I wanted to rearrange a `CommentedMap` type using custom sorting, this is could be appropriate, or else it wouldn't be able to serialize. Not sure if the `CommentedMap` constructor would have been able to be used for this. – NanoTree Jun 13 '23 at 17:11