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

Han Li
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Han Li
Python Web Development Techdegree Graduate 14,817 Points
Posted by Han Li
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Han Li
Python Web Development Techdegree Graduate 14,817 Points

First Slice

Hi,

I got the following error

"Bummer: Didn't get the right values from reverse_evens"

Thanks, Ross

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

def first_and_last_4(items):
    return items[0:4] + items[-4:]

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

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

1 Answer

Steven Parker
Steven Parker
231,275 Points
Steven Parker
Steven Parker
231,275 Points

This strategy will work with some test data, but not every time.

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.