A and B but not C in list

[Steven D'Aprano]

On Sun, 23 Jan 2011 22:34:33 +0100, Christian Heimes wrote:

> It's easier and faster if you convert the lists to sets first:
> 
> your_set = set(your_list)
> 
> if your_set.issuperset(set([A, B])) and your_set.isdisjoint(set([C,
> D])):
>     ...

"Easier" is a close thing. I find this easier to remember and write than 
set processing, even if it is a couple of characters longer:

if all(x in your_list for x in (A, B)) and not any(x in your_list for x 
in (C, D)):
    ...

And as for "faster", surely that will depend on the number of elements in 
your_list? The conversion from list to set doesn't happen for free, and 
it's likely that for small enough lists, that time may exceed any time 
savings you would otherwise gain.


-- 
Steven