[Tutor] Looking for duplicates within a list

[Steven D'Aprano]

On Sat, 12 Jun 2010 12:58:19 am Alan Gauld wrote:

> Have you looked at the count method of lists?
>
> Something like:
>
> counts = set(( item, mylist.count(item)) for item in mylist if
> mylist.count(item) > 1)

That's a Shlemiel the Painter algorithm.

http://www.joelonsoftware.com/articles/fog0000000319.html


> Seems to work...

You say that now, but one day you will use it on a list of 100,000 
items, and you'll wonder why it takes 45 minutes to finish, and curse 
Python for being slow.





-- 
Steven D'Aprano