Tricky Dictionary Question from newbie

[Ric Da Force]

Thank you guys! (Reinhold, Mark and Markus)  I must confess that I am 
absolutely awe struck at the power of this language!  There is no way in the 
world that I would have envisaged such simple and elegant solutions!!!

Reinhold, is your solution specific to 2.4?

Kind Regards,

Ric

"Reinhold Birkenfeld" <reinhold-birkenfeld-nospam at wolke7.net> wrote in 
message news:3jftckFpvhv2U2 at individual.net...
> Mark Jackson wrote:
>> "Ric Da Force" <ric at next-level.com.au> writes:
>>
>>> It is hard to explain but this is what I mean:
>>>
>>> Dict = {'rt': 'This is repeated', 'sr': 'This is repeated', 'gf': 'This 
>>> is
>>> not'}
>>>
>>> I want this to return a new dict with string keys and lists containing 
>>> the
>>> previous keys for repeated values.
>>>
>>> NewDict = {'This is repeated':['rt','sr'],'This is not':['gf']}
>>
>> NewDict = {}
>> for x in Dict.keys():
>> try:
>> NewDict[Dict[x]].append(x)
>> except KeyError:
>> NewDict[Dict[x]] = [x]
>
> Or, more up-to-date:
>
> NewDict = {}
> for key, val in Dict.iteritems():
>    NewDict.setdefault(val, []).append(key)
>
> Reinhold