Python | Divide constant to Kth Tuple index

Many times, while working with records, we can have a problem in which we need to change the value of tuple elements. This is a common problem while working with tuples. Let’s discuss certain ways in which N can be divided by Kth element of tuple in list. 

Method #1: Using loop Using loops this task can be performed. In this, we just iterate the list to change the Kth element by predefined value N in code. 

Python3

# Python3 code to demonstrate working of
# Divide constant to Kth Tuple index
# Using loop

# Initializing list
test_list = [(4, 5, 6), (7, 4, 2), (9, 10, 11)]

# printing original list
print("The original list is : " + str(test_list))

# Initializing N
N = 3

# Initializing K
K = 1

# Divide constant to Kth Tuple index
# Using loop
res = []
for i in range(0, len(test_list)):
    res.append((test_list[i][0], test_list[i][K] // N, test_list[i][2]))

# printing result
print("The tuple after dividing N to Kth element : " + str(res))

Output

The original list is : [(4, 5, 6), (7, 4, 2), (9, 10, 11)]
The tuple after dividing N to Kth element : [(4, 1, 6), (7, 1, 2), (9, 3, 11)]

Time complexity: O(n), where n is the length of the input list test_list.
Auxiliary space: O(n), since we are creating a new list res to store the modified tuples.

Method #2: Using list comprehension This method is having the same approach as the above method, just reduces lines of code using list comprehension functionality to make code compact by size. 

Python3

# Python3 code to demonstrate working of
# Divide constant to Kth Tuple index
# Using list comprehension

# Initializing list
test_list = [(4, 5, 6), (7, 4, 2), (9, 10, 11)]

# printing original list
print("The original list is : " + str(test_list))

# Initializing N
N = 3

# Initializing K
K = 1

# Divide constant to Kth Tuple index
# Using list comprehension
res = [(a, b // N, c) for a, b, c in test_list]

# printing result
print("The tuple after dividing N to Kth element : " + str(res))

Output

The original list is : [(4, 5, 6), (7, 4, 2), (9, 10, 11)]
The tuple after dividing N to Kth element : [(4, 1, 6), (7, 1, 2), (9, 3, 11)]

Time Complexity: O(n),The above code iterates through the list once, hence the time complexity is linear, i.e. O(n).
Space Complexity: O(n),The algorithm uses an additional list to store the result, thus consuming linear space which is O(n).

Method #3 :Using map() and lambda functions

The map() function can be used along with the lambda functions to change the value of a specific element in the tuple.

Python3

#Python3 code to demonstrate working of
#Divide constant to Kth Tuple index
#Using map() and lambda functions
#Initializing list
test_list = [(4, 5, 6), (7, 4, 2), (9, 10, 11)]

#printing original list
print("The original list is : " + str(test_list))

#Initializing N
N = 3

#Initializing K
K = 1

#Divide constant to Kth Tuple index
#Using map() and lambda functions
res = list(map(lambda x : (x[0], x[K] // N, x[2]), test_list))

#printing result
print("The tuple after dividing N to Kth element : " + str(res))
#This code is contributed by Edula Vinay Kumar Reddy

Output

The original list is : [(4, 5, 6), (7, 4, 2), (9, 10, 11)]
The tuple after dividing N to Kth element : [(4, 1, 6), (7, 1, 2), (9, 3, 11)]

Time complexity: O(n), where n is the number of tuples in the list.
Auxiliary Space: O(n)

Method 4: Using the numpy library. 

Step-by-step approach:

• Import the numpy library.
• Initialize the input list as a numpy array.
• Use the numpy.divide() function to divide the Kth column by N.
• Print the updated numpy array.

Python3

#Python3 code to demonstrate working of
#Divide constant to Kth Tuple index
#Using numpy

import numpy as np

#Initializing list
test_list = [(4, 5, 6), (7, 4, 2), (9, 10, 11)]

#printing original list
print("The original list is : " + str(test_list))

#Initializing N
N = 3

#Initializing K
K = 1

#Converting the list to a numpy array
arr = np.array(test_list)

#Dividing Kth column by N
arr[:, K] = np.divide(arr[:, K], N)

#printing result
print("The tuple after dividing N to Kth element : " + str(arr.tolist()))

OUTPUT : 
The original list is : [(4, 5, 6), (7, 4, 2), (9, 10, 11)]
The tuple after dividing N to Kth element : [[4, 1, 6], [7, 1, 2], [9, 3, 11]]

The time complexity for this approach would be O(n), where n is the number of tuples in the input list.
The auxiliary space complexity would be O(n), since we are creating a new numpy array to store the result.