In Python, you can use sort or sorted to sort a list.
But what is the difference between the two? This is what I will discuss in this article.
First: Sorting a Python List using Sort
sort() is a method on the list object.
Say, you have an arbitrary list L and you want to sort it. Here is what you can do.
>>> L = [5, 3, 7] >>> L.sort() >>> L [3, 5, 7]
There is one thing that I want to notice: L was sorted in-place. This means that no new lists were created.
You can double check that using the id built-in function.
>>> L = [5, 3, 7] >>> id(L) 4477543040 >>> L.sort() >>> L [3, 5, 7] >>> id(L) 4477543040
Having the same id means that the location of the object is the same before and after sorting, which confirms that sorting happened in-place.
Now let’s talk about sorted().
Second: Sorting a Python List using Sorted
Unlike sort, sorted is not a method.
sorted() is a built-in function like print() or id().
Let’s try to use sorted to sort the same list from above.
>>> L = [5, 3, 7] >>> sorted(L) [3, 5, 7] >>> L [5, 3, 7]
It doesn’t seem to work, does it? It looks like L hasn’t changed. Why is that?
Unlike sort, sorted creates a new list object and sorts the elements of the original list L in this new object without modifying the original list.
This is an essential difference between sort and sorted.
You can easily confirm that by inspecting the ids.
>>> L = [5, 3, 7] >>> id(L) 4477542848 >>> id(sorted(L)) 4477542976
So with that in mind, the correct way to use sorted is as follows:
>>> L = [5, 3, 7] >>> Q = sorted(L) >>> Q [3, 5, 7]
So essentially, if you want to sort the elements of a list in place, use the sort method. But if you want to sort the items of a list in a new list object without modifying the original list, use the sorted built-in function.
What sorting algorithm is used for sort and sorted?
If you want to know more about Timsort and its superior performance, then I highly recommend reading this.
- How to sort a list of numbers? (ascendignly or descendignly)/a>
- How to sort a list of strings
- How to sort a list of tuples?
- How to sort a list of arbitrary objects?
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