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Python Python Collections (2016, retired 2019) Slices Introduction To Slices

l.sort()

Why the return of the variable is None

l = [1,2,4,3] cleanL= l.sort() print cleanL

None

Cheo R
Cheo R
37,150 Points

sort(), sorts in place, returning None. If you print l before and after calling sort you should see a sorted list.

Sorry not sure if you are explaining this when you are saying sort in place, but why the sorted list is not assigned to the variable cleanL

Cheo R
Cheo R
37,150 Points

It's like l is sorted, then reassigned to l, the sort function then returns None, which in your example is assigned to cleanL. So when you print cleanL, you see None. Try printing your l variable before and after calling the sort function on it, also trying calling l.sort() inside a print function to see what it returns.

great many thanks!

1 Answer

Steven Parker
Steven Parker
231,236 Points

The sort method does not return anything.

As Cheo pointed out, it just modifies the array it is applied to. Try this instead:

cleanL = l = [1,2,4,3]
cleanL.sort() 
print(cleanL)

Code formatting is particularly important for Python (in Python, indentation is everything). So when posting code, use the instructions for code formatting in the Markdown Cheatsheet pop-up below the "Add an Answer" area. :arrow_heading_down: