testing if a list contains a sublist

MRAB python at mrabarnett.plus.com
Tue Aug 16 18:41:55 CEST 2011


On 16/08/2011 00:26, Johannes 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.
>
Here's my solution, using the Counter class:

 >>> from collections import Counter
 >>>
 >>> c1 = Counter([1,2])
 >>> c2 = Counter([1,2,3,4,5])
 >>> (c1 & c2) == c1
True
 >>>
 >>> c1 = Counter([1,2,2,])
 >>> c2 = Counter([1,2,3,4,5])
 >>> (c1 & c2) == c1
False
 >>>
 >>> c1 = Counter([1,2,3])
 >>> c2 = Counter([1,3,5,7])
 >>> (c1 & c2) == c1
False



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