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

Posted by mamadou diene
.a{fill-rule:evenodd;}techdegree
mamadou diene
Python Web Development Techdegree Student 1,971 Points

You're on fire! Last one and it is, of course, the hardest. Make a function named reverse_evens that accepts a single i

i need pointers in this challenge please

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

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

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

def reverse_evens(ilovechallenge):
    return ilovechallenge[::-2]

1 Answer

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

Well, they do admit this one is tough. But there's basically two strategies you can use, one is to compute the starting position based on the length of the list and then you can use a single slice. The other is to use one slice to get the even indexed items, and another to reverse the list. Either will pass the challenge.

mamadou diene
.a{fill-rule:evenodd;}techdegree
mamadou diene
Python Web Development Techdegree Student 1,971 Points

This is still not passing

def first_4(treehouse): return treehouse[0:4]

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

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

def reverse_evens(ilovechallenge): return ilovechallenge[-1:-14:-2]

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

no single slice with fixed values will work for all possible inputs. You must either compute the starting position or do it with two slices. You might want to take a look at other questions asked about this challenge.