Strip outer elements from list that are contained in another list

Question

I'm trying to remove all outer elements of a list that are contained in a second list, while keeping ones that may be 'sandwiched' inside. I know how to take the complement of the intersection of two sets, but here I just want to remove all beginning and trailing elements. So far I've come up with the following, but it feels clunky:

def strip_list(l, to_remove):
    while l[0] in to_remove:
        l.pop(0)
    while l and l[-1] in to_remove:
        l.pop(-1)
    return l

mylist = ['one', 'two', 'yellow', 'one', 'blue', 'three', 'four']
nums = ['one', 'two', 'three', 'four']
strip_list(mylist, nums)
# > ['yellow', 'one', 'blue']

@sytech that would removed also duplicates that should be left — Uriel, Nov 14 '16 at 15:07
Possible duplicate of [Remove all the elements that occur in one list from another](http://stackoverflow.com/questions/4211209/remove-all-the-elements-that-occur-in-one-list-from-another) — damores, Nov 14 '16 at 15:13

score 1 · Accepted Answer · answered Nov 14 '16 at 16:00

1

def strip_list(data, to_remove):  
    idx = [i for i, v in enumerate(data) if v not in to_remove]  
    return data[idx[0]:idx[-1]+1]

answered Nov 14 '16 at 16:00

dugres

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lol, i am working on exactly same piece of code, this will fail if all items from input list match inside to_remove list – Skycc Nov 14 '16 at 16:09
1

change the return to return data[idx[0]:idx[-1]+1] if idx else [] , then shall be perfect – Skycc Nov 14 '16 at 16:17

Strip outer elements from list that are contained in another list

1 Answers1