Python | Tuple Column element frequency

In python we need to handle various forms of data and one among them is list of tuples in which we may have to perform any kind of operation. This particular article discusses the ways of finding the frequency of the Kth element in list of tuple. Let’s discuss certain ways in which this can be performed. 
Method #1 : Using map() + count() The map function can be used to accumulate the indices of all the tuples in a list and the task of counting the frequency can be done using the generic count function of python library. 

Python3

# Python3 code to demonstrate
# Tuple Column element frequency
# using map() + count()

# initializing list of tuples
test_list = [(1, 'Geeks'), (2, 'for'), (3, 'Geeks')]

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

# initializing K
K = 1

# using map() + count()
# Tuple Column element frequency
res = list(map(lambda i : i[K], test_list)).count('Geeks')

# printing result
print ("The frequency of element at Kth index is : " + str(res))

Output : 

The original list is : [(1, 'Geeks'), (2, 'for'), (3, 'Geeks')]
The frequency of element at Kth index is : 2

Time complexity: O(n),
Auxiliary space: O(1).

Method #2 : Using Counter() + list comprehension List comprehension performs the task of getting the Kth element of the tuples and the counting part is handled by Counter function of collection library. 

Python3

# Python3 code to demonstrate
# Tuple Column element frequency
# using Counter() + list comprehension
from collections import Counter

# initializing list of tuples
test_list = [(1, 'Geeks'), (2, 'for'), (3, 'Geeks')]

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

# initializing K
K = 1

# using Counter() + list comprehension
# Tuple Column element frequency
res = Counter(i[K] for i in test_list)

# printing result
print ("The frequency of element at Kth index is : " + str(res['Geeks']))

Output : 

The original list is : [(1, 'Geeks'), (2, 'for'), (3, 'Geeks')]
The frequency of element at Kth index is : 2

Time complexity: O(n), where n is the length of the input list.

Space complexity: O(k), where k is the number of unique elements at the Kth index of the input list.

Method 3:using a simple for loop

using a simple for loop to iterate through the list of tuples and maintain a dictionary to keep track of the frequency of elements at Kth index.

Python3

# initializing list of tuples
test_list = [(1, 'Geeks'), (2, 'for'), (3, 'Geeks')]

# initializing K
K = 1

# using for loop to count frequency
freq_dict = {}
for tup in test_list:
    if tup[K] in freq_dict:
        freq_dict[tup[K]] += 1
    else:
        freq_dict[tup[K]] = 1

# printing result
print("The frequency of element at Kth index is :", freq_dict['Geeks'])

Output

The frequency of element at Kth index is : 2

The time complexity of this approach is O(n), where n is the length of the list of tuples. 

The space complexity is O(k), where k is the number of distinct elements at Kth index.