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

Posted by Ben Bruder
Ben Bruder
9,130 Points

The last task won't work, why?

The rest of the tasks passed, but the last one just says 'Didn't get the right value from reverse_evens'. I even tested it in the workspace and it worked there.

slices.py 
def first_4(listt):
    return listt[:4]
def first_and_last_4(listt):
    one = first_4(listt)
    one.extend(listt[-4:])
    return one
def odds(listt):
    return listt[1::2]
def reverse_evens(listt):
    return listt[-1::-2]

2 Answers

Alexander Davison
Alexander Davison
65,469 Points

Your function reverse_evens doesn't work in all cases. You must take a two-step process: first get the evens; then reverse it.

Try:

def reverse_evens(my_list):
    return my_list[::2][::-1]
Ben Bruder
Ben Bruder
9,130 Points

Thanks, it worked!

Adam Paciorek
Adam Paciorek
3,181 Points
Adam Paciorek
Adam Paciorek
3,181 Points

any ideas why this does not pass?

My function is :

def reverse_evens(list):
    reversed_list = list[::-1]
    return reversed_list[::2]
Alexander Davison
Alexander Davison
65,469 Points

You need to first get the even-indexed elements, then reverse it. They aren't the same, they sometimes return different results!