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

Jair Anguiano
Jair Anguiano
3,225 Points

I tested my code of the evens in reverse and it worked, but it didn't when press recheck

def reverse_evens(foo): reverse = foo[::-1] evens = [] for idx, val in enumerate(reverse): if (idx % 2) == 0: evens.append(val) else: pass return evens

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

def first_and_last_4(foo):
    first = foo[:4]
    last = foo[-4:]
    return first + last

def odds(foo):
    odds=[]
    for idx, val in enumerate(foo):
        if (idx % 2) == 0:
            pass
        else:
            odds.append(foo[idx]) 
    return odds

def reverse_evens(foo):
    reverse = foo[::-1]
    evens = []
    for  idx, val in enumerate(reverse):
        if (idx % 2) == 0:
            evens.append(val)
        else:
            pass
    return evens

1 Answer

Steven Parker
Steven Parker
215,954 Points

The "even indexes" they are asking for are the ones that are even in the original list. Once you reverse the list, the ones you want could be even or odd depending on the length of the list. So you might do either one of two things:

  • use the list length to determine which ones to take
  • get the even indexed items first and then reverse the order

Either way, this can be done without a loop by using slicing.

Jair Anguiano
Jair Anguiano
3,225 Points

Get it, thank you very much!

Steven Parker
Steven Parker
215,954 Points

Jair Anguiano — Glad to help. You can mark a question solved by choosing a "best answer".
And happy coding!