Python List - Reverse - Using reverse(), slicing

Python - Reverse a List

To reverse the order of items in a list, or simply said reverse a list, use reverse() method of List Class.

In this tutorial, we shall first discuss about the trivial reverse() function to reverse a Python List. Then we shall go through some of the unconventional approaches to reverse a list, for widening our Python knowledge.

Syntax of reverse()

The syntax of reverse() method is given below.

mylist.reverse()

Another method of reversing a list is using slicing. Following statement reverses and returns the resulting list.

reversed_list = mylist[::-1]

Examples

1. Reverse a given list of numbers using reverse()

In the following example, we have a List of numbers. We will reverse the list using reverse() method.

Python Program

# A list of numbers
mylist = [21, 5, 8, 52, 21, 87, 52]
# Reverse the list
mylist.reverse()
# Print the list
print(mylist)

Output

[52, 87, 21, 52, 8, 5, 21]

Explanation

  1. The list starts as [21, 5, 8, 52, 21, 87, 52].
  2. The reverse() method is called, which reverses the list in place.
  3. The original list is updated to [52, 87, 21, 52, 8, 5, 21].

2. Reverse the list using slicing

In this example, we will use slicing technique and reverse the given list.

Python Program

# List of numbers
mylist = [21, 5, 8, 52, 21, 87, 52]
# Reverse list using slicing
mylist = mylist[::-1]
# Print the list
print(mylist)

Output

[52, 87, 21, 52, 8, 5, 21]

Explanation

  1. The list starts as [21, 5, 8, 52, 21, 87, 52].
  2. Slicing with [::-1] creates a new reversed list.
  3. The original list remains unchanged, but the variable is reassigned to the reversed list.

3. Reverse a given list of strings

In this example, we reverse a list of strings.

Python Program

# List of strings
mylist = ['list', 'dict', 'set']
# Reverse the list
mylist.reverse()
# Print the list
print(mylist)

Output

['set', 'dict', 'list']

Explanation

  1. The list starts as ['list', 'dict', 'set'].
  2. The reverse() method reverses the list in place.
  3. The modified list becomes ['set', 'dict', 'list'].

4. Reverse a mixed data type list

In this example, we reverse a list containing different data types.

Python Program

# List with mixed data types
mylist = [1, 'hello', 3.14, True]
# Reverse the list
mylist.reverse()
# Print the list
print(mylist)

Output

[True, 3.14, 'hello', 1]

Explanation

  1. The list starts as [1, 'hello', 3.14, True].
  2. The reverse() method reverses the list in place.
  3. The modified list becomes [True, 3.14, 'hello', 1].

5. Reverse list using recursion

This example demonstrates reversing a list using recursion.

Python Program

# Recursive function to reverse a list
def reverse_list(lst):
    if len(lst) == 0:
        return []
    return [lst[-1]] + reverse_list(lst[:-1])

# List to reverse
mylist = [21, 5, 8, 52]
# Call the recursive function
reversed_list = reverse_list(mylist)
# Print the reversed list
print(reversed_list)

Output

[52, 8, 5, 21]

Explanation

  1. The function reverse_list is called with the input list.
  2. It appends the last element of the list to the result of the function called on the rest of the list.
  3. The final reversed list is returned as [52, 8, 5, 21].

Summary

In this tutorial of Python Examples, we learned how to reverse a Python List, with the help of well-detailed example programs.



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