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Python Python Basics (2015) Python Data Types Lists

Posted by Keith Ostertag
Keith Ostertag
16,619 Points

Using lists, why does b = a.sort() not work?

Just playing around, I thought I could do this:

>>> a = [3, 8, 2, 9, 1]
>>> b = a.sort()
>>> b
>>>

What's the rule that makes this invalid?

Of course this works:

>>> b = a
>>> b
[1, 2, 3, 8, 9]

1 Answer

Steven Parker
Steven Parker
229,732 Points
Steven Parker
Steven Parker
229,732 Points

The sort() method does not return a value.

It just sorts the list that you apply it to. But it doesn't return anything you can assign to another variable.

To do that, you could use sorted instead:

b = sorted(a)
Keith Ostertag
Keith Ostertag
16,619 Points

Thanks Steven. I was looking at the docs for data structures (https://docs.python.org/3/tutorial/datastructures.html) which doesn't give that detail. Can you tell me where to find that level of detail for list methods?

Steven Parker
Steven Parker
229,732 Points
Steven Parker
Steven Parker
229,732 Points

You were in the right place, but on a different page. What you want can be found in the description of sort in the list methods

[MOD: typo corrections -cf]