Topic: “Filter numbers with a list comprehension” (PyBite #107)

[bowlofred]

Do all list comprehensions automatically somehow know to append list items automatically?

Sorta, yes. They are list comprehensions, so they return a list of the elements. You don't have to create it by manually appending anything. Likewise a dict comprehension will populate a dict, and a set comprehension will append to a set.

r = range(-5, 6)
l = [x for x in r if x % 2 == 0] # all the even numbers.  l is created here, no appending to other list.
print(l)

Output:
[-4, -2, 0, 2, 4]

In your attempt you are appending the entire list generated into an empty list. So you just get an extra level of nesting.