Why this Python expression doesn't produce expected result?

Question

This code snippet:

a = [3, 2, 1]
a.sort()

produces [1, 2, 3] list. Why

[3, 2, 1].sort()

doesn't produce the same result? Is there a "one-liner" to accomplish this?

Answer 1

>>> [3, 2, 1].sort()

It does sort this list object but as the number of references(variables pointing) to this list are 0, so it is garbage collected.(i.e we can't access this list anymore)

Coming to your first question, list.sort() sorts a list in-place and returns None.

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

If you want a to stay as it is, use sorted and assign the result back to some variable.

>>> a = [3, 2, 1]
>>> b = sorted(a)
>>> b
[1, 2, 3]
>>> a
[3, 2, 1]

Answer 2

You can use
sorted_array = sorted([2,3,1])

Answer 3

list.sort is a method that sorts an existing list therefore returning None

sorted is a builtin function that creates a new sorted list from its input and returns it.