[Tutor] Simple way to compare Two lists

Andy Cheesman Andy.cheesman at bristol.ac.uk
Fri Aug 10 14:02:28 CEST 2007

I think you could use sets, (I asked a similar question a few days ago
re numpy arrays).
Convert both list to sets
use Set intersection
convert answer to lists



Tom Fitzhenry wrote:
> On Fri, Aug 10, 2007 at 02:54:44AM -0700, Jaggo wrote:
>> Can anyone think of any better way?
> If SmallList and BigList are sorted (in order), there is a faster method:
> def IsAPartOfList(SmallList,BigList):
>     for i in BigList:
>         for j in SmallList:
>             if i==j:
>                 return true
>             if i>j:
>                 break
>     return false
> (I'm not sure how encouraged using break statements are, so wait for a tutor to
> answer)
> If one list is already sorted but the other isn't, it may still be faster to
> sort the unsorted list then use the method above.
> If neither SmallList or BigList are sorted, it's probably best to use your
> original method, which I cannot improve.

More information about the Tutor mailing list