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Python Python Collections (2016, retired 2019) Slices Slice Functions

Bruce Röttgers
Bruce Röttgers
18,211 Points

reverse_evens returns wrong values

Hey, I wrote the code found attached. In the challenge reverse_evens seems to be returning the wrong values but in my local editor it returns the correct answer.

slices.py
def first_4(l):
    return l[:4]

def first_and_last_4(l):
    return first_4(l) + l[-4:]

def odds(l):
    return l[1::2]

def reverse_evens(l):
    return l[::-2]

1 Answer

Steven Parker
Steven Parker
231,275 Points

You're half right. Your method will work when the list has an odd number of items. But when the list has an even number of items, it will return reverse odds instead.

To always return reverse evens, there's two basic strategies:

  • compute the starting position based on the list size
  • extract the even index values first, then reverse them

Either one will pass the challenge when implemented correctly.