Python – List with most unique elements

Sometimes, while working with data, we can have a problem in which we need to compute the list which has most number of unique elements. This can have application in many domains. Lets discuss certain ways in which this task can be performed.

Method #1 : Using list comprehension + max() + set()
The combination of above functionalities can be used to solve this problem. In this, we compute the maximum occurring elements using max() and reduce the logic to uniqueness using set().

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# Python3 code to demonstrate 
# List with most unique elements
# using list comprehension + max() + set()
  
# Initializing lists
test_list1 = [1, 3, 4, 4, 4, 3, 3, 2, 2, 1]
test_list2 = [1, 3, 4, 6, 7]
test_list3 = [4, 5, 4, 3, 6, 7, 8]
  
# printing original lists
print("The original list 1 is : " + str(test_list1))
print("The original list 2 is : " + str(test_list2))
print("The original list 3 is : " + str(test_list3))
  
# List with most unique elements
# using list comprehension + max() + set()
res = [ele for ele in [set(test_list1), set(test_list2), set(test_list3)]
      if len(ele) == max([len(sub) for sub in [set(test_list1), set(test_list2), set(test_list3)]])][0]
  
# printing result 
print ("List with Most unique values : " + str(list(res)))

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Output :

The original list 1 is : [1, 3, 4, 4, 4, 3, 3, 2, 2, 1]
The original list 2 is : [1, 3, 4, 6, 7]
The original list 3 is : [4, 5, 4, 3, 6, 7, 8]
List with Most unique values : [3, 4, 5, 6, 7, 8]

 

Method #2 : Using max() + set() + key
This task can also be performed using combination of above functions. In this, we extract the maximum frequency list using max() and key argument len.

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# Python3 code to demonstrate 
# List with most unique elements
# using key + max() + set()
  
# Initializing lists
test_list1 = [1, 3, 4, 4, 4, 3, 3, 2, 2, 1]
test_list2 = [1, 3, 4, 6, 7]
test_list3 = [4, 5, 4, 3, 6, 7, 8]
  
# printing original lists
print("The original list 1 is : " + str(test_list1))
print("The original list 2 is : " + str(test_list2))
print("The original list 3 is : " + str(test_list3))
  
# List with most unique elements
# using key + max() + set()
temp = [set(test_list1), set(test_list2), set(test_list3)]
res = max(temp, key = len)
  
# printing result 
print ("List with Most unique values : " + str(list(res)))

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Output :

The original list 1 is : [1, 3, 4, 4, 4, 3, 3, 2, 2, 1]
The original list 2 is : [1, 3, 4, 6, 7]
The original list 3 is : [4, 5, 4, 3, 6, 7, 8]
List with Most unique values : [3, 4, 5, 6, 7, 8]



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