Python – Remove Kth Index Duplicates in Tuple

Sometimes, while working with Python records, we can have a problem in which we need to remove all the tuples, which have similar Kth index elements in list of records. This kind of problem is common in day-day and web development domain. Let’s discuss certain ways in which this task can be performed.

Input : test_list = [(4, 5, 6), (2, 3, 4), (1, 3, 4), (7, 6, 4), (1, 2, 6)], K = 1
Output : [(4, 5, 6), (2, 3, 4), (7, 6, 4), (1, 2, 6)]

Input : test_list = [(4, 5, 6), (2, 3, 4), (1, 3, 4), (7, 6, 4), (1, 2, 6)], K = 0
Output : [(4, 5, 6), (2, 3, 4), (1, 3, 4), (7, 6, 4)]

Method #1 : Using loop
This is one of the ways in which this task can be performed. In this, we perform the task of memoizing already occurred Kth index element in set, and check each time with new value.

# Python3 code to demonstrate working of
# Remove Kth Index Duplicates in Tuple
# Using loop

# initializing lists
test_list = [(4, 5, 6), (2, 3, 4), (1, 3, 4), (7, 6, 4), (1, 2, 6)]

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

# initializing K
K = 2

# Remove Kth Index Duplicates in Tuple
# Using loop
keep = set()
res = []
for sub in test_list:
    if sub[K] not in keep:
        res.append(sub)
        keep.add(sub[K])

# printing result
print("Filtered Tuples : " + str(res))

Output :

The original list is : [(4, 5, 6), (2, 3, 4), (1, 3, 4), (7, 6, 4), (1, 2, 6)]
Filtered Tuples : [(4, 5, 6), (2, 3, 4)]

Method #2 : Using groupby() + itemgetter() + list comprehension
The combination of above functions can be used to solve this problem. In this, we perform the task of checking for Kth element using itemgetter() and groupby() is used to form groups, out of which we extract 1st element by accessing 0th index.

# Python3 code to demonstrate working of
# Remove Kth Index Duplicates in Tuple
# Using groupby() + itemgetter() + list comprehension
from itertools import groupby
from operator import itemgetter

# initializing lists
test_list = [(4, 5, 6), (2, 3, 4), (1, 3, 4), (7, 6, 4), (1, 2, 6)]

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

# initializing K
K = 2

# Remove Kth Index Duplicates in Tuple
# Using groupby() + itemgetter() + list comprehension
res = res = [list(val)[0] for key, val in groupby(sorted(test_list,
                        key = itemgetter(K)), key = itemgetter(K))]

# printing result
print("Filtered Tuples : " + str(res))

Output :

The original list is : [(4, 5, 6), (2, 3, 4), (1, 3, 4), (7, 6, 4), (1, 2, 6)]
Filtered Tuples : [(4, 5, 6), (2, 3, 4)]