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

Soumik Rakshit
Soumik Rakshit
2,745 Points
Posted by Soumik Rakshit
Soumik Rakshit
2,745 Points

The last function is not passing on Treehouse but is giving correct answer on the Python 3.6 IDLE. Please Help.

The last function passes the list [1,2,3,4,5] and asks the output [5,3,1]. I returned a[::-2] but it is not passing on Treehouse but is giving correct answer on the Python 3.6 IDLE.

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

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

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

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

1 Answer

Steven Parker
Steven Parker
229,732 Points
Steven Parker
Steven Parker
229,732 Points

:warning: Be careful about testing a challenge in an external IDLE or REPL.

If you have misunderstood the challenge, it's also very likely that you will misinterpret the results.

In this case, you did not consider that the correct offset would be different for a list with an even number of items compared to one with an odd number of items. To produce the correct result in both cases, you'll need to either compute the offset based on the length of the list, or break the task up into steps and use two slices.