Question

I have two lists:

l1 = ['#', '1', '#', '!']
l2 = ['S', 'T', 'K', 'M']

If there is a ‘#’ in l1 I want to remove it, and remove whatever is at the same position in l2.
This is what I have tried (among several other things):

for i in range(len(li[j])):
    for k in range(len(l2[n])):
        if j == "#":
            li.remove([j][i])
            l2.remove([n][k])

But it complains that j is not defined.
I want the outcome to look like this:

l1 = ['1', '!']
l2 = ['T', 'M']

I would be grateful for suggestions!

Answer 1

Here is a simple and easy to understand method:

a = ["#", "1", "#", "2", "3", "#"]
b = ["a", "b", "c", "d", "e", "f"]

a,b = zip(*[[a[i], b[i]] for i in range(len(a)) if a[i]!="#"])
print a
print b

Personally I find it much simplier to understand and more effective (read: “faster”) than the method @jamylak proposed.

Output:

>>> 
('1', '2', '3')
('b', 'd', 'e')