在保持顺序的同时设置减法

Question

I know with set subtraction I can do the following:

l2 = set([4,3,5,2])
l1 = set([3,8])
l2 - l1
set([2, 4, 5])

How would I do this same thing, while keeping the ordering in l1 . For example:

l2 = [4,3,5,2] 
l1 [3,8]
# remove 3, keep other ordering
l2 - l1
[4,5,2]

Answer 1

l1 = [4,3,5,2]
l2 = [3]
# remove 3, keep other ordering
st = set(l2)

print([x for x in l1 if x not in st])

[4, 5, 2]

Just make l2 a set and use in keeping elements from l1 that are not in st . set lookups are 0(1) so you still have an efficient solution.