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

SUVODEEP DUBEY
SUVODEEP DUBEY
2,470 Points
Posted by SUVODEEP DUBEY
SUVODEEP DUBEY
2,470 Points

def reverse_evens(sl): return(sl[-1:-(len(sl)+1):-2]) Returning the reverse evens for task 4

def reverse_evens(sl): return(sl[-1:-(len(sl)+1):-2])

Please verify I am getting the correct output for reverse_evens

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

def first_and_last_4(sl):
    fir_4 = sl[:4]
    las_4 = sl[-4:]
    j_fir_las = []
    j_fir_las.extend([i for i in fir_4])
    j_fir_las.extend([i for i in las_4])
    return j_fir_las

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

def reverse_evens(sl):
    return(sl[-1:-(len(sl)+1):-2])

1 Answer

Chris Freeman
MOD
Chris Freeman
Treehouse Moderator 68,441 Points
Chris Freeman
Chris Freeman
Treehouse Moderator 68,441 Points

The solution can not be found in a single slice since the number of items in the argument is unknown. Using your code:

>>> def reverse_evens(sl):
...     return(sl[-1:-(len(sl)+1):-2])
>>> reverse_evens([0,1,2,3,4,5])
[5, 3, 1]
>>> reverse_evens([0,1,2,3,4,5,6])
[6, 4, 2, 0]

Hint: First get the even-indexed items, then reverse them

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