Python | Reversing a Tuple
Last Updated :
08 May, 2023
As we know that in Python, tuples are immutable, thus it cannot be changed or altered. This provides us with limited ways of reversing a tuple, unlike a list. We will go through few techniques on how a tuple in python can be reversed. Examples:
Input : tuples = ('z','a','d','f','g','e','e','k')
Output : ('k', 'e', 'e', 'g', 'f', 'd', 'a', 'z')
Input : tuples = (10, 11, 12, 13, 14, 15)
Output : (15, 14, 13, 12, 11, 10)
Method 1: Using the slicing technique. In this technique, a copy of the tuple is made and the tuple is not sorted in-place. Since tuples are immutable, there is no way to reverse a tuple in-place. Creating a copy requires more space to hold all of the existing elements. Therefore, this exhausts memory.
Python3
def Reverse(tuples):
new_tup = tuples[::-1]
return new_tup
tuples = ('z','a','d','f','g','e','e','k')
print(Reverse(tuples))
|
Output:
('k', 'e', 'e', 'g', 'f', 'd', 'a', 'z')
The time complexity is O(n), where n is the number of elements in the input tuple.
The auxiliary space is also O(n),
Method 2: Using the reversed() built-in function. In this method, we do not make any copy of the tuple. Instead, we get a reverse iterator which we use to cycle through the tuple, similar to the list.
Python
def Reverse(tuples):
new_tup = ()
for k in reversed(tuples):
new_tup = new_tup + (k,)
print new_tup
tuples = (10, 11, 12, 13, 14, 15)
Reverse(tuples)
|
Output:
(15, 14, 13, 12, 11, 10)
Method3: Iteration
One alternative approach you could use is to create a new empty tuple and then iterate through the original tuple in reverse order, adding each element to the new tuple. This approach requires creating a new tuple and adding each element one by one, so it may be less efficient than the other methods.
Here is an example of how you could use this approach to reverse a tuple:
Python3
def reverse_tuple(t):
new_tuple = ()
for i in range(len(t)-1, -1, -1):
new_tuple += (t[i],)
return new_tuple
tuples = ('z','a','d','f','g','e','e','k')
print(reverse_tuple(tuples))
|
Output
('k', 'e', 'e', 'g', 'f', 'd', 'a', 'z')
Method4: Using Recursion
Python3
def reverse_tuple(t):
if len(t) == 0:
return t
else:
return(t[-1],)+reverse_tuple(t[:-1])
original_tuple = ('z','a','d','f','g','e','e','k')
reversed_tuple = reverse_tuple(original_tuple)
print("Original Tuple: ", original_tuple)
print("Reversed Tuple: ", reversed_tuple)
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Output
Original Tuple: ('z', 'a', 'd', 'f', 'g', 'e', 'e', 'k')
Reversed Tuple: ('k', 'e', 'e', 'g', 'f', 'd', 'a', 'z')
Time complexity : O(n)
Auxiliary space : O(n)
Approach#5:using join()+reversed()
Algorithm
1.Convert the tuple to a string using join().
2.Use reversed() to reverse the string.
3.Convert the reversed string back to a tuple using the tuple() function.
Python3
tuples = ('z', 'a', 'd', 'f', 'g', 'e', 'e', 'k')
rev_string = ''.join(tuples)[::-1]
rev_tuples = tuple(rev_string)
print(rev_tuples)
|
Output
('k', 'e', 'e', 'g', 'f', 'd', 'a', 'z')
Time Complexity: O(n), where n is the number of elements in the tuple.
Space Complexity: O(n), where n is the number of elements in the tuple.
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