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

Posted by mochammad yalinulloh
mochammad yalinulloh
Courses Plus Student 3,002 Points

How to resolve this challenge?

Make a function named reverse_evens that accepts a single iterable as an argument. Return every item in the iterable with an even index...in reverse.

For example, with [1, 2, 3, 4, 5] as the input, the function would return [5, 3, 1].

so when i create the function, the result is right in my console But not right in challenge

this is my code

def reverse_event(data): return data[-1::-2]

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

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

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

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

1 Answer

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

Someone asked nearly the same question just 20 minutes before! The trick is that this strategy will work with some test data, but not every time. You managed to test with "lucky data".

To create a function that will work reliably with all data, there are two basic approaches:

  • compute which item to start with based on the size (or actually the "even or odd-ness") of the list, or
  • use one slice to extract all the even indexed values, and then another slice to reverse them

Either method will work when implemented correctly. Bonus hint: the second method might be easier to implement.

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

Oleksandr Krasnovskyy — Does that mean you got it? You can mark a question solved by choosing a "best answer".

And happy coding!