Paul McGuire <[EMAIL PROTECTED]> wrote:
> Instead of all that try/except noise, just use the new defaultdict:
>
> >>> from collections import defaultdict
> >>>
> >>> d = {'a' : 1, 'b' : 3, 'c' : 2,'d' : 3,'e' : 1,'f' : 4}
> >>>
> >>> dd = defaultdict(list)
> >>> for key, value in d.items():
> ... dd[value].append(key)
> ...
> >>> for k,v in dd.items():
> ... print k,':',v
> ...
> 1 : ['a', 'e']
> 2 : ['c']
> 3 : ['b', 'd']
> 4 : ['f']
>
Or use the little understood dict.setdefault method which has been
with us from time immemorial...
>>> d = {'a' : 1, 'b' : 3, 'c' : 2,'d' : 3,'e' : 1,'f' : 4}
>>> dd = {}
>>> for k, v in d.items():
... dd.setdefault(v, []).append(k)
...
>>> dd
{1: ['a', 'e'], 2: ['c'], 3: ['b', 'd'], 4: ['f']}
>>>
--
Nick Craig-Wood <[EMAIL PROTECTED]> -- http://www.craig-wood.com/nick
--
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