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Python Python Collections (Retired) Slices Slice Functions

Posted by martinvoigt
martinvoigt
1,676 Points

List Slicing

Why does this not work:

def first_and_last_4(iterable):
  return iterable[:4].extend(iterable[-4:])

1 Answer

Kenneth Love
STAFF
Kenneth Love
Treehouse Guest Teacher
Kenneth Love
Kenneth Love
Treehouse Guest Teacher

slicing creates a new list in memory, while .extend() expects to work on a list in-place. I'm pretty sure those two are just not compatible with each other.

You can, however, concatenate two slices with +.

martinvoigt
martinvoigt
1,676 Points

Thank you very much :D