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

GEORGIOS VLACHOULIS
GEORGIOS VLACHOULIS
1,427 Points
Posted by GEORGIOS VLACHOULIS
GEORGIOS VLACHOULIS
1,427 Points

Python collections, second challenge, task 4/4 My code : def reverse_evens(x): return x[::-2] Won't accept it

Googled it, 10 times, watched the video 5 times,tryied code in Atom and Brackets and worked. Maybe I don't get something. I'd like to use some help here please..

slices.py 
def first_4(list1):
    return list1[0:4]
def first_and_last_4(list2):
    return list2[0:4]+list2[-4:]
def odds(list3):
    return list3[1::2]
def reverse_evens(x):
    return x[::-2]

1 Answer

Steven Parker
Steven Parker
229,657 Points
Steven Parker
Steven Parker
229,657 Points

You're half right. Based on the length of the list, that code will return the even indexed items in reverse sometimes.

But to make it work every time, you'll need to implement one of these two strategies:

  • use the length of the list to determine which item to start with
  • extract the even indexes first, then reverse them in a separate operation

Either method will do the job when implemented correctly (but the second one might be easier).

GEORGIOS VLACHOULIS
GEORGIOS VLACHOULIS
1,427 Points
GEORGIOS VLACHOULIS
GEORGIOS VLACHOULIS
1,427 Points

Thank you very much for your assistance!