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

Posted by Kyler Aagard
Kyler Aagard
1,331 Points

How do I reverse the order of numbers?

I've created a variable that takes the right numbers that I need reversed, but I haven't been taught any commands on how to reverse the order. I know I can .sort(), but that will sort from low to high. Is there a command to sort from high to low?

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

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

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

def reverse_evens(iterable):
    iterable_1 = iterable[1::2]

    return

1 Answer

Timothy Long
.a{fill-rule:evenodd;}techdegree
Timothy Long
Front End Web Development Techdegree Student 6,833 Points

In Python, using a negative number for the "step" argument on the list slicing syntax will tell python to start at the last index and work backwards. For example, say I have a list letters = ['a', 'b', 'c'] and want to print it out backwards.

I can do letters[::-1] and I will get ['c', 'b', 'a'].

I hope that helps. If you're still stuck I can provide an example that exactly answers the question.