# Find sum of frequency of given elements in the list in Python

PythonServer Side ProgrammingProgramming

A given list has many repeated items. We are interested in finding out the sum of the frequency of some such items which are repeated in the list. Below are the approaches how we can achieve this.

## With sum

We have two lists. One has the list of values and other has the values whose frequency needs to be checked from the first list. So we create a for loop to count the number of occurrences of the elements from the second list in the first list and then apply the sum function to get the final sum of frequency.

## Example

Live Demo

chk_list= ['Mon', 'Tue']
big_list = ['Mon','Tue', 'Wed', 'Mon','Mon','Tue']

# Apply sum
res = sum(big_list.count(elem) for elem in chk_list)

# Printing output
print("Given list to be analysed: \n", big_list)
print("Given list to with values to be analysed:\n", chk_list)
print("Sum of the frequency: ", res)

## Output

Running the above code gives us the following result −

Given list to be analysed:
['Mon', 'Tue', 'Wed', 'Mon', 'Mon', 'Tue']
Given list to with values to be analysed:
['Mon', 'Tue']
Sum of the frequency: 5

## With collections.Counter

The Counter function from collections module can get the desired result by applying it to the list whose values have to be analysed while looping through the smaller list which has only the elements whose frequency needs to be established.

## Example

Live Demo

from collections import Counter

chk_list= ['Mon', 'Tue']
big_list = ['Mon','Tue', 'Wed', 'Mon','Mon','Tue']

# Apply Counter

res = sum(Counter(big_list)[x] for x in chk_list)

# Printing output
print("Given list to be analysed: \n", big_list)
print("Given list to with values to be analysed:\n", chk_list)
print("Sum of the frequency: ", res)

## Output

Running the above code gives us the following result −

Given list to be analysed:
['Mon', 'Tue', 'Wed', 'Mon', 'Mon', 'Tue']
Given list to with values to be analysed:
['Mon', 'Tue']
Sum of the frequency: 5