testing if a list contains a sublist

Simon Forman sajmikins at gmail.com
Sat Aug 20 18:06:38 CEST 2011


On Mon, Aug 15, 2011 at 4:26 PM, Johannes <dajo.mail at web.de> wrote:
> hi list,
> what is the best way to check if a given list (lets call it l1) is
> totally contained in a second list (l2)?
>
> for example:
> l1 = [1,2], l2 = [1,2,3,4,5] -> l1 is contained in l2
> l1 = [1,2,2,], l2 = [1,2,3,4,5] -> l1 is not contained in l2
> l1 = [1,2,3], l2 = [1,3,5,7] -> l1 is not contained in l2
>
> my problem is the second example, which makes it impossible to work with
> sets insteads of lists. But something like set.issubset for lists would
> be nice.
>
> greatz Johannes
> --
> http://mail.python.org/mailman/listinfo/python-list
>

Probably not the most efficient way, but I wanted to mention it:


from difflib import SequenceMatcher


def list_in(a, b):
    '''Is a completely contained in b?'''
    matcher = SequenceMatcher(a=a, b=b)
    m = matcher.find_longest_match(0, len(a), 0, len(b))
    return m.size == len(a)


Cheers,
~Simon



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