Python List reverse() Method
list.reverse() flips the order of the items in a list in place and returns None; it does not sort anything.reverse() simply turns the list around: the first item becomes the last and the last becomes the first. It does not look at the values at all, so [3, 1, 2] becomes [2, 1, 3], not [3, 2, 1]. If you want values in descending order, use sort(reverse=True) instead.
There are three common ways to get a reversed list, and choosing the right one depends on whether you want to change the original. See also slicing for the [::-1] form.
| Syntax | my_list.reverse() |
|---|---|
| Parameters | None |
| Returns | None (the list is modified in place) |
| Time complexity | O(n) |
How list.reverse() reverses a list in place
The method swaps items from the two ends toward the middle. No new list is created, so every name that refers to the list sees the change.
laps = ["first", "second", "third"]
laps.reverse()
print(laps)reverse() vs reversed() vs slicing [::-1]
Pick the tool by what you need back.
| Tool | Changes original? | Returns | Works on |
|---|---|---|---|
my_list.reverse() | Yes | None | Lists only |
reversed(seq) | No | A reverse iterator (wrap in list() to see it) | Sequences, and objects with __reversed__ |
seq[::-1] | No | A new reversed sequence of the same type | Lists, tuples, strings, ranges |
When reverse() is the right choice
Use reverse() when you own the list and want to flip it without extra memory, for example turning a stack's contents into reading order. Use reversed() when you only want to loop backwards over a list: for x in reversed(items) avoids creating a copy. Use slicing when you need a new list or when the data is a tuple or string, which have no reverse() method. The Python reverse a list guide compares all the approaches in detail.
Examples you can run
Press Run, then edit the code and run it again.
Reverse a list in place
The list order is flipped and the variable still points at the same list.
nums = [1, 2, 3, 4]
nums.reverse()
print(nums)Expected output[4, 3, 2, 1]
Keep the original with slicing or reversed()
Both leave scores untouched.
scores = [70, 85, 90]
print(scores[::-1])
print(list(reversed(scores)))
print(scores)Expected output[90, 85, 70]
[90, 85, 70]
[70, 85, 90]
Sort and reverse are different
reverse() ignores the values; sort(reverse=True) orders them.
a = [3, 1, 2]
b = [3, 1, 2]
a.reverse()
b.sort(reverse=True)
print(a)
print(b)Expected output[2, 1, 3]
[3, 2, 1]
Common mistakes
Using the return value
✗ Wrong
items = [1, 2, 3]
items = items.reverse()
print(items)✓ Right
items = [1, 2, 3]
items.reverse()
print(items)reverse() returns None. Call it alone, or use items[::-1] to get a new list.
Calling reverse() on a tuple or string
✗ Wrong
point = (1, 2, 3)
point.reverse()✓ Right
point = (1, 2, 3)
print(point[::-1])Use slicing point[::-1] or tuple(reversed(point)). See AttributeError.
Printing a reversed() object
✗ Wrong
nums = [1, 2, 3]
print(reversed(nums))✓ Right
nums = [1, 2, 3]
print(list(reversed(nums)))reversed() returns an iterator. Wrap it in list() to see the items.
Python List reverse() Method: questions people ask
How do I reverse a list in Python?
Call my_list.reverse() to flip it in place, or use my_list[::-1] or list(reversed(my_list)) to get a new reversed list.
Does reverse() sort the list in descending order?
No. It only flips the current order. To get descending order use my_list.sort(reverse=True).
Does reverse() return the reversed list?
No, it returns None because it changes the list in place.
Keep learning
Step-by-step lessons:
Python ListsPython List MethodsPython Slicing
Related:
Python List sort() MethodHow to Reverse a List in PythonPython List copy() MethodPython List Methods
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