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Python Reverse List

Python provides multiple ways to reverse the elements in a list.

Python Reverse List Elements

The following techniques can be used to reverse a Python List:

  • By using the reversed() function
  • By using the reverse() function
  • By using Slicing technique
  • By using for loop and range() function

1. reversed() function

The reversed() method creates a reverse iterator to traverse through the list in reverse order.

def reverse_list(input): 
	return [x for x in reversed(input)] 
	
 
input = [0, 22, 78, 1, 45, 9] 
print(reverse_list(input)) 

Output:

[9, 45, 1, 78, 22, 0]

2. reverse() function

The reverse() function provides the functionality to reverse the elements and store them within the same list instead of copying the elements into another list and then reversing it.

def reverse_list(input): 
    input.reverse() 
    return input 
      
input = [0, 22, 78, 1, 45, 9]
print(reverse_list(input)) 

Output:

[9, 45, 1, 78, 22, 0]

3. Slicing technique

The slicing technique provides the functionality to reverse the list.

def reverse_list(input): 
	output = input[::-1] 
	return output 
	
input = [0, 22, 78, 1, 45, 9]
print(reverse_list(input)) 

Output:

[9, 45, 1, 78, 22, 0]

4. By using for loop and range() function

input = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
 
# Get list length
list_len = len(input)
 
# i goes from 0 to the middle
for x in range(int(list_len/2)):
    
    n = input[x]
    input[x] = input[list_len-x-1]
    input[list_len-x-1] = n
 
# At this point the list should be reversed
print(input)

Output:

[9, 8, 7, 6, 5, 4, 3, 2, 1, 0]

Conclusion

Thus, in this article, we have understood and implemented various techniques to reverse a list in Python.


References