Python | Program to count duplicates in a list of tuples

Last Updated : 11 Dec, 2018

Given a list of tuples, write a Python program to check if an element of the list has duplicates. If duplicate exist, print the number of occurrence of each duplicate tuple, otherwise print “No Duplicates”.

Examples:

Input : [(‘a’, ‘e’), (‘b’, ‘x’), (‘b’, ‘x’), (‘a’, ‘e’), (‘b’, ‘x’)]
Output :
(‘a’, ‘e’) – 2
(‘b’, ‘x’) – 3
Input : [(0, 5), (6, 9), (0, 8)]
Output : No Duplicates

Let’s see the various ways we can count duplicates in a list of tuples.

Approach #1 : Naive Approach

This approach uses two loops to traverse the list elements and check if the first element and second element of each element matches any other tuple.

# Python3 code to convert tuple 
# into string
def count(listOfTuple):
      
    flag = False
  
    # To append Duplicate elements in list
    coll_list = []  
    coll_cnt = 0
    for t in listOfTuple:
          
        # To check if Duplicate exist
        if t in coll_list:  
            flag = True
            continue
          
        else:
            coll_cnt = 0
            for b in listOfTuple:
                if b[0] == t[0] and b[1] == t[1]:
                    coll_cnt = coll_cnt + 1
              
            # To print count if Duplicate of element exist
            if(coll_cnt > 1): 
                print(t, "-", coll_cnt)
            coll_list.append(t)
                       
    if flag == False:
        print("No Duplicates")
  
# Driver code
print("Test Case 1:")
listOfTuple = [('a', 'e'), ('b', 'x'), ('b', 'x'), 
               ('a', 'e'), ('b', 'x')] 
  
count(listOfTuple)
  
print("Test Case 2:")
listOfTuple = [(0, 5), (6, 9), (0, 8)]
count(listOfTuple)

Output:

Test Case 1:
('a', 'e') - 2
('b', 'x') - 3

Test Case 2:
No Duplicates

Time complexity – O(n)²

Approach #2 : Using Counter

Counter is a container included in the collections module. It is an unordered collection where elements and their respective count are stored as dictionary.

# Python3 code to convert tuple 
# into string
import collections
  
def count(listOfTuple):
      
    flag = False
    val = collections.Counter(listOfTuple)
    uniqueList = list(set(listOfTuple))
      
    for i in uniqueList:
        if val[i]>= 2:
            flag = True
            print(i, "-", val[i])
              
    if flag == False:
        print("Duplicate doesn't exist")
  
# Driver code
listOfTuple = [('a', 'e'), ('b', 'x'), ('b', 'x'), 
               ('a', 'e'), ('b', 'x')] 
count(listOfTuple)

Output:

('b', 'x') - 3
('a', 'e') - 2

Time complexity – O(n)

Approach #3 : Using another dict

You can make a dictionary, say count_map, and store the count of each tuple as the value.

# Python3 code to convert tuple 
# into string
def count(listOfTuple):
      
    count_map = {}
    for i in listOfTuple:
        count_map[i] = count_map.get(i, 0) +1
    print(count_map)
  
# Driver code
print("Test Case 1:")
listOfTuple = [('a', 'e'), ('b', 'x'), ('b', 'x'), 
               ('a', 'e'), ('b', 'x')] 
  
count(listOfTuple)

Output:

Test Case 1:
{('a', 'e'): 2, ('b', 'x'): 3}

Time complexity – O(n)

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Python | Program to count duplicates in a list of tuples