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Python Python Collections (2016, retired 2019) Slices Back and Forth

Posted by nick fonseca
nick fonseca
2,331 Points

Cant sort list

for some reason I cant get past challenge question 3. Sorting the list. 

favorite_things = ['raindrops on roses', 'whiskers on kittens', 'bright copper kettles',
                   'warm woolen mittens', 'bright paper packages tied up with string',
                   'cream colored ponies', 'crisp apple strudels']

slice1 = favorite_things[1:4]
slice2 = favorite_things[-2:]
sorted_things = favorite_things[:]
sorted_things = favorite_things.sort()

What am I missing?

slices.py 
favorite_things = ['raindrops on roses', 'whiskers on kittens', 'bright copper kettles',
                   'warm woolen mittens', 'bright paper packages tied up with string',
                   'cream colored ponies', 'crisp apple strudels']

slice1 = favorite_things[1:4]
slice2 = favorite_things[-2:]
sorted_things = favorite_things[:]
sorted_things = favorite_things.sort()

2 Answers

Alex Koumparos
seal-mask
.a{fill-rule:evenodd;}techdegree
Alex Koumparos
Python Development Techdegree Student 36,887 Points
Alex Koumparos
.a{fill-rule:evenodd;}techdegree
Alex Koumparos
Python Development Techdegree Student 36,887 Points

Hi Nick,

The instructions tell you:

Then use .sort() to sort sorted_things.

You are using .sort() to sort favourite_things.

Note that sort() sorts a list in-place and returns nothing, so when you do this:

sorted_things = favorite_things.sort()

You are changing favorite_things by applying sort(). It then returns nothing, so you are assigning None to sorted_things.

Cheers

Alex

nick fonseca
nick fonseca
2,331 Points

like this:

favorite_things = sorted_things[:]
favorite_things = sorted_things.sort()
Alex Koumparos
seal-mask
.a{fill-rule:evenodd;}techdegree
Alex Koumparos
Python Development Techdegree Student 36,887 Points
Alex Koumparos
.a{fill-rule:evenodd;}techdegree
Alex Koumparos
Python Development Techdegree Student 36,887 Points

Hi Nick,

Let's take a look at the instructions (task 3). You are being asked to:

Make a copy of favorite_things and name it sorted_things.

You are doing the opposite: making a copy of sorted_things and naming it favorite_things. Depending on what other code you have that is not included in your snippet, you may not even have a variable called sorted_things to make a copy of, so you'll probably get an error that sorted_things is not defined: NameError: name 'sorted_things' is not defined.

Next you are being asked to:

Then use .sort() to sort sorted_things.

In your line:

favorite_things = sorted_things.sort()

You are doing that (the code on the right side of the assignment operator), but then you are also assigning the value of None to favorite_things which you were not told to do (and will thus get the following error: Don't change or sort `favorite_things`!).

Cheers

Alex