Python List reverse()

Python List reverse() is an inbuilt method in the Python programming language that reverses objects of the List in place i.e. it doesn’t use any extra space but it just modifies the original list.

Python List reverse() Syntax

Syntax: list_name.reverse()

Parameters: There are no parameters.

Returns: The reverse() method does not return any value but reverses the given object from the list.

List reverse() in Python Example

Reverse a list using list reverse()

Here we are reversing the list using the list reverse() function in Python.

Python3

# Python3 program to demonstrate the
# use of reverse method

# a list of numbers
list1 = [1, 2, 3, 4, 1, 2, 6]
list1.reverse()
print(list1)

# a list of characters
list2 = ['a', 'b', 'c', 'd', 'a', 'a']
list2.reverse()
print(list2)

Output:

[6, 2, 1, 4, 3, 2, 1]
['a', 'a', 'd', 'c', 'b', 'a']

Error in reverse() Method

When anything other than list is used in place of list, then it returns an AttributeError.

Python3

# Python3 program to demonstrate the
# error in reverse() method

# error when string is used in place of list
string = "abgedge"
string.reverse()
print(string)

Output:

Traceback (most recent call last):
 File "/home/b3cf360e62d8812babb5549c3a4d3d30.py", line 5, in 
   string.reverse() 
AttributeError: 'str' object has no attribute 'reverse' 

Reverse a List using the Slicing Operator

In this example, the [::-1] slicing operator creates a new list which is the reverse of the my_list.

Python3

my_list = [1, 2, 3, 4, 5]
reversed_list = my_list[::-1]
print(reversed_list)

Output :

[5, 4, 3, 2, 1]

Reversing a sublist using Slicing

In this example, we are reversing a sublist from index 1 to 3 using [::-1] operator.

Python3

my_list = [1, 2, 3, 4, 5]
print('Original list:', my_list)
my_list[1:4] = my_list[1:4][::-1]
print('Reversed sublist:', my_list)

Output :

Original list: [1, 2, 3, 4, 5]
Reversed sublist: [1, 4, 3, 2, 5]

Accessing Elements in Reversed Order

In this example, we are traversing the list in the reverse order.

Python3

my_list = [1, 2, 3, 4, 5]
for element in reversed(my_list):
    print(element)

Output :

5
4
3
2
1

Reversing a list of mixed DataTypes

In this example, we are reversing the list of mixed data types with the reverse() function.

Python3

my_list = [1, 'apple', 2.5, True]
print('Original list:', my_list)
my_list.reverse()
print('Reversed list:', my_list)

Output :

Original list: [1, 'apple', 2.5, True]
Reversed list: [True, 2.5, 'apple', 1]

Practical Application

Given a list of numbers, check if the list is a palindrome. 

Python3

# Python3 program for the
# practical application of reverse()
list_arr = [1, 2, 3, 2, 1]
list_string = list("naman")

# store a copy of list
list2 = list_arr.copy()
list3 = list_string.copy()

# reverse the list
list2.reverse()
list3.reverse()

# compare reversed and original list
if list_arr == list2:
    print(list_arr, ": Palindrome")
else:
    print(list_arr, ": Not Palindrome")

# compare reversed and original list
if list_string == list3:
    print(list_string, ": Palindrome")
else:
    print(list_string, ": Not Palindrome")

Output

[1, 2, 3, 2, 1] : Palindrome
['n', 'a', 'm', 'a', 'n'] : Palindrome

Note: Palindrome-sequence that reads the same backward as forwards.