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Hwang Ju
2,847 Pointswhy does this not work?: def reverse_evens(arg): return arg[::-2]
Please help!
def first_4(arg):
return arg[:4]
def first_and_last_4(arg):
return first_4(arg) + arg[-4:]
def odds(arg):
return arg[1::2]
def reverse_evens(arg):
return arg[::-2]
3 Answers
Jason Anello
Courses Plus Student 94,610 PointsHi Hwang Ju,
Doing a step of -2 is only going to work for certain lists. The problem is that you don't know if the last item is an even or an odd index.
See the following output:
>>> [1, 2, 3, 4, 5][::-2]
[5, 3, 1]
>>> [1, 2, 3, 4][::-2]
[4, 2]
>>>
It works out for the given example because the 5 is at index 4 and you end up getting indexes 4, 2, 0
The second example doesn't work because the 4 is at index 3 and you end up getting indexes 3, 1
I don't know if it's possible to do this in one slice without additional logic. I solved it with 2 slices.
The first slice gets the even indexes and then a slice on that to reverse it.
arg[::2][::-1]
Hwang Ju
2,847 PointsThank you very much! Happy holidays!
Hwang Ju
2,847 PointsYou're on fire! Last one and it is, of course, the hardest. 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]. You can do it!
That was the question asked. -1 is incorrect
Ammar Fatihallah
7,417 Pointsoh i though you were on another quiz, my bad. i tried to run the code on mt terminal and it ran with no problem. I also tried redoing the quiz with your code and it passed with no problem, maybe its an internet connection problem ???
Ammar Fatihallah
7,417 PointsAmmar Fatihallah
7,417 Pointsin the reverse_evans, you should the return to arg[::-1] rather than arg[::-2]