Python – Kth Column Product in Tuple List

Sometimes, while working with Python list, we can have a task in which we need to work with tuple list and get the product of it’s Kth index. This problem has application in web development domain while working with data informations. Let’s discuss certain ways in which this task can be performed.

Method #1 : Using list comprehension + loop
This task can be performed using the combination of above functionalities. In this, product of index occurs using explicit product function and list comprehension drives the iteration and access of Kth index element of each tuple in list.

# Python3 code to demonstrate working of
# Tuple List Kth Column Product
# using list comprehension + loop

# getting Product
def prod(val) :
    res = 1
    for ele in val:
        res *= ele
    return res

# initialize list
test_list = [(5, 6, 7), (1, 3, 5), (8, 9, 19)]

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

# initialize K
K = 2

# Tuple List Kth Column Product
# using list comprehension + loop
res = prod([sub[K] for sub in test_list])

# printing result
print("Product of Kth Column of Tuple List : " + str(res))

Output :

The original list is : [(5, 6, 7), (1, 3, 5), (8, 9, 19)]
Product of Kth Column of Tuple List : 665

Method #2 : Using imap() + loop + itemgetter()
The combination of above functions can also achieve this task. This approach is generator based and recommended in case we have a very large list. In this, product function is used to perform product, itemgetter to get Kth index and imap() performs the task of mapping elements to extract product. Works only in Python2.

# Python code to demonstrate working of
# Tuple List Kth Column Product
# using imap() + loop + itemgetter()
from operator import itemgetter
from itertools import imap

# getting Product
def prod(val) :
    res = 1
    for ele in val:
        res *= ele
    return res

# initialize list
test_list = [(5, 6, 7), (1, 3, 5), (8, 9, 19)]

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

# initialize K
K = 2

# Tuple List Kth Column Product
# using imap() + loop + itemgetter()
idx = itemgetter(K)
res = prod(imap(idx, test_list))

# printing result
print("Product of Kth Column of Tuple List : " + str(res))

Output :

The original list is : [(5, 6, 7), (1, 3, 5), (8, 9, 19)]
Product of Kth Column of Tuple List : 665