Python | Frequency grouping of list elements

Sometimes, while working with lists, we can have a problem in which we need to group element along with it’s frequency in form of list of tuple. Let’s discuss certain ways in which this task can be performed.

Method #1 : Using loop
This is a brute force method to perform this particular task. In this, we iterate each element, check in other list for it’s presence, if yes, then increase it’s count and put to tuple.

# Python3 code to demonstrate working of
# Frequency grouping of list elements
# using loop

# initialize list
test_list = [1, 3, 3, 1, 4, 4]

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

# Frequency grouping of list elements
# using loop
res = []
temp = dict()
for ele in test_list:
    if ele in temp:
        temp[ele] = temp[ele] + 1
    else :
        temp[ele] = 1
for key in temp:
    res.append((key, temp[key]))

# printing result
print("Frequency of list elements : " + str(res))

Output :

The original list : [1, 3, 3, 1, 4, 4]
Frequency of list elements : [(1, 2), (3, 2), (4, 2)]

Method #2 : Using Counter() + items()
The combination of two functions can be used to perform this task. They perform this task using inbuild constructs and are a shorthand to perform this task.

# Python3 code to demonstrate working of
# Frequency grouping of list elements
# using Counter() + items()
from collections import Counter

# initialize list
test_list = [1, 3, 3, 1, 4, 4]

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

# Frequency grouping of list elements
# using Counter() + items()
res = list(Counter(test_list).items())

# printing result
print("Frequency of list elements : " + str(res))

Output :

The original list : [1, 3, 3, 1, 4, 4]
Frequency of list elements : [(1, 2), (3, 2), (4, 2)]