I have a few lists that I want filtered. Consider the following example:
a = [1,2]
b = [2,3]
l = [a,b]
for i in l:
i = [elem for elem in l if elem != 2]
I want the output to be a==[1], b==[3], but it looks like the update of i does not change the elements a or b. In C++, I'd use a pointer but I can't seem to find the corresponding concept in Python.
By assigning to i a new list in your for loop, it loses its reference to a and b so they do not get updated. Instead, you should update i in-place. You should also iterate through i instead of l to filter each sub-list:
for i in l:
i[:] = (elem for elem in i if elem != 2)