Checking if a list element is inside another list if so, substitute every element inside the base list

Question

So I currently have a bunch of mocks list such as this one. Sample:

l = ['a','a','c','d']
l2 = ['c','b','b','d']
l3 = ['c','b','b','d','x','z']
l4 = ['a','c','a','a']

What I want to do is check if any of the values inside each of these lists, is equal to any of the values inside another list.

target_l = ['a','b']

If so i want to change every element inside these lists into the matched element.

Wanted result:

l = ['a','a','a','a']
l2 = ['b','b','b','b']
l3 = ['b','b','b','b','b','b']
l4 = ['a','a','a','a']

Answer 1

Here is how you can do it for l:

for e in target_l:
    if e in l:
        l = [e]*len(l)
        break