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

Posted by Rachael A
Rachael A
1,044 Points

Reverse evens question, why does this work in sublime but not here?

In sublime if I input the same info I get this as the answer [5, 3, 1] so why doesn't my solution pass?

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

def first_and_last_4(items):
    return items[:4] + items[-4:]

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

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

1 Answer

Chris Freeman
MOD
Chris Freeman
Treehouse Moderator 68,423 Points
Chris Freeman
Chris Freeman
Treehouse Moderator 68,423 Points

Keep in mind that the length of the list to reverse may have an even or odd number of items. A simple reversal of every other item is not sufficient.

Hint: try grabbing the even indexed items first, then reversing that list in a second slice.

Post back if you need more help. Good luck!!!

Rachael A
Rachael A
1,044 Points

I eventually passed with this:

def reverse_evens(items):
    if len(items) %2!=0:
        return items[-1::-2]
    else:
        return items[-2::-2]
Chris Freeman
Chris Freeman
Treehouse Moderator 68,423 Points
Chris Freeman
Chris Freeman
Treehouse Moderator 68,423 Points

You can also use two slices with no if 

return items[::2][::-1]