Python | Nth tuple index Subtraction by K

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 K can be subtracted to Nth 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 Nth element by predefined value K in code. 

Python3

# Python3 code to demonstrate working of
# Nth tuple element Subtraction by K
# 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 = 1

# Initializing K
K = 3

# Nth tuple element Subtraction by K
# Using loop
res = []
for i in range(0, len(test_list)):
    res.append((test_list[i][0], test_list[i][N] - K, test_list[i][2]))

# printing result
print("The tuple after removing K from Nth element : " + str(res))

Output : 

The original list is : [(4, 5, 6), (7, 4, 2), (9, 10, 11)]
The tuple after removing K from Nth element : [(4, 2, 6), (7, 1, 2), (9, 7, 11)]

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
# Nth tuple element Subtraction by K
# 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 = 1

# Initializing K
K = 3

# Nth tuple element Subtraction by K
# Using list comprehension
res = [(a, b - K, c) for a, b, c in test_list]

# printing result
print("The tuple after removing K from Nth element : " + str(res))

Output

The original list is : [(4, 5, 6), (7, 4, 2), (9, 10, 11)]
The tuple after removing K from Nth element : [(4, 2, 6), (7, 1, 2), (9, 7, 11)]

Method #3 : Using map()
This method is also having the same approach as the above two methods, but uses the map() function to make the code concise.

Python3

# Python3 code to demonstrate working of
# Nth tuple element Subtraction by K
# Using map()

# 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 = 1

# Initializing K
K = 3

# Nth tuple element Subtraction by K
# Using map()
res = list(map(lambda x : (x[0], x[N] - K, x[2]), test_list))

# printing result
print("The tuple after removing K from Nth 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 removing K from Nth element : [(4, 2, 6), (7, 1, 2), (9, 7, 11)]

Time complexity: O(N)
Auxiliary Space: O(N)