Testing for an empty dictionary in Python

John Nagle nagle at animats.com
Sun Mar 23 16:00:09 EDT 2008


Brian Lane wrote:
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> John Nagle wrote:
>>    What's the cheapest way to test for an empty dictionary in Python?
>>
>> 	if len(dict.keys()) :
>>
>> is expensive for large dictionaries, and makes loops O(N^2).
>>
>> 					John Nagle
> 
> if dict:

    Cute.

    I'd already figured out that

	len(dict)

works, which is probably better than
	
	len(dict.keys() > 0

which requires creating a list.

				John Nagle



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