Testing for an empty dictionary in Python

D'Arcy J.M. Cain darcy at druid.net
Sun Mar 23 16:52:30 CET 2008

On Sun, 23 Mar 2008 08:53:02 -0700
John Nagle <nagle at animats.com> wrote:
>    What's the cheapest way to test for an empty dictionary in Python?
> 	if len(dict.keys() > 0) :
> is expensive for large dictionaries, and makes loops O(N^2).

Try this:

    if dict:

It should be faster as it only checks whether or not there are
any members and does not run keys() or len() on the dictionary.  Of
course, you should test it.

D'Arcy J.M. Cain <darcy at druid.net>         |  Democracy is three wolves
http://www.druid.net/darcy/                |  and a sheep voting on
+1 416 425 1212     (DoD#0082)    (eNTP)   |  what's for dinner.

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