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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