Python Program to Find Most common elements set

Last Updated : 02 Feb, 2021

Given a List of sets, the task is to write a Python program tocompare elements with argument set, and return one with maximum matching elements.

Examples:

Input : test_list = [{4, 3, 5, 2}, {8, 4, 7, 2}, {1, 2, 3, 4}, {9, 5, 3, 7}], arg_set = {9, 6, 5, 3}
Output : {9, 3, 5, 7}
Explanation : Resultant set has maximum matching elements.

Input : test_list = [{4, 3, 5, 2}, {8, 4, 7, 2}, {1, 2, 3, 4}, {9, 5, 3, 7}], arg_set = {4, 6, 5, 3}
Output : {2, 3, 4, 5}
Explanation : Resultant set has maximum matching elements.

Method 1: Using loop + set.intersection()

In this, we perform task of getting all the common elements with argument set using intersection(), and get its length using len(), and maximum length and set is compared and updated during iteration.

Python3

# Python3 code to demonstrate working of
# Most common elements set
# Using loop + intersection()
  
# initializing list
test_list = [{4, 3, 5, 2}, {8, 4, 7, 2},
             {1, 2, 3, 4}, {9, 5, 3, 7}]
  
# printing original list
print("The original list is : " + str(test_list))
  
# initializing arg_set
arg_set = {9, 6, 5, 3}
  
res = set()
max_len = 0
  
for sub in test_list:
      
    # updating max value on occurrence
    if len(sub.intersection(arg_set)) > max_len:
        max_len = len(sub.intersection(arg_set))
        res = sub
  
# printing result
print("Max Set intersection : " + str(res))

Output:

The original list is : [{2, 3, 4, 5}, {8, 2, 4, 7}, {1, 2, 3, 4}, {9, 3, 5, 7}]
Max Set intersection : {9, 3, 5, 7}

Method 2 : Using max() + list comprehension + intersection()

In this, initial step is to check for the lengths of all intersected set results and get maximum using max(). Next, task of getting set which matches required length is extracted.

Python3

# Python3 code to demonstrate working of
# Most common elements set
# Using loop + intersection()
  
# initializing list
test_list = [{4, 3, 5, 2}, {8, 4, 7, 2},
             {1, 2, 3, 4}, {9, 5, 3, 7}]
  
# printing original list
print("The original list is : " + str(test_list))
  
# initializing arg_set
arg_set = {9, 6, 5, 3}
  
# getting maximum length 
max_len = max(len(sub.intersection(arg_set)) for sub in test_list)
  
# getting element matching length
res = [sub for sub in test_list if len(sub.intersection(arg_set)) == max_len][0]
  
# printing result
print("Set intersection : " + str(res))

Output:

The original list is : [{2, 3, 4, 5}, {8, 2, 4, 7}, {1, 2, 3, 4}, {9, 3, 5, 7}]
Max Set intersection : {9, 3, 5, 7}

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