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

Posted by SImon Comerford
SImon Comerford
1,438 Points

Make a function named reverse_evens that accepts a single i

this works perfectly in work spaces but i cannot pass the challenge! am i missing something...

slices.py 
def first_4(insertword):
    return insertword[0:4]

def first_and_last_4(morestuffhere):
    return morestuffhere[0:4] + morestuffhere[-4:]

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

def reverse_evens(hardest):
    return hardest[-1::-2]

1 Answer

Wesley Trayer
Wesley Trayer
13,812 Points
Wesley Trayer
Wesley Trayer
13,812 Points

The mistake is easy to make. "reverse_evens" assumes the last item in the iterable is in an even position, but what if it is odd?

a = ['a', 'b', 'c', 'd', 'e', 'f', 'g']  # The last item is in position 6, so your code returns the even items
b = ['a', 'b', 'c', 'd', 'e', 'f']  # The last item is in position 5, so your code returns the odd items

So you first need to get the even items starting from the beginning, then reverse their order.

Hope this helps!