Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

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

Posted by Lerena Holloway
Lerena Holloway
9,855 Points

Reversing a list using negative integers

I was finishing up the challenge on lists. It was to print out the list in reverse order, but every other index. I wrote this code and it didn't work. But when I copied it and pasted it into my Spider text editor, it gave back the example they used; it worked. I'm not sure why it's not working in the challenge editor.

Here's my code:

def reverse_evens(some_list): reverse_list = some_list[::-1] return reverse_list[::2]

Thanks for your help!

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

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

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

def reverse_evens(some_list):
    reverse_list = some_list[::-1]
    return reverse_list[::2]

1 Answer

Steven Parker
Steven Parker
231,269 Points
Steven Parker
Steven Parker
231,269 Points

With the current code, whether you get "reverse evens" or "reverse odds" will depend on the length of the list.

Try slicing the even indexes first, and then reversing that list.

Lerena Holloway
Lerena Holloway
9,855 Points

That worked! Thanks