Python | Remove tuples having duplicate first value from given list of tuples

Last Updated : 29 Mar, 2019

Given a list of tuples, the task is to remove all tuples having duplicate first values from the given list of tuples.

Examples:

Input:  [(12.121, 'Tuple1'), (12.121, 'Tuple2'), 
         (12.121, 'Tuple3'), (923232.2323, 'Tuple4')]
Output:  [(12.121, 'Tuple1'), (923232.2323, 'Tuple4')]

Input:  [('Tuple1', 121), ('Tuple2', 125), 
         ('Tuple1', 135), ('Tuple4', 478)]
Output:  [('Tuple1', 121), ('Tuple2', 125), ('Tuple4', 478)]

Below are some ways to achieve the above task.

Method #1: Using Iteration

# Python code to remove tuples having  
# duplicate first value from given 
# list of tuples 
  
# Input list initialization 
Input = [(12.121, 'Geeksforgeeks is best'),  
         (19212.22, 'India is best'),  
         (12.121, 'Cyware is best.'), 
         (923232.2323, 'Jiit is best')] 
  
# using set 
visited = set() 
  
# Output list initialization 
Output = [] 
  
# Iteration 
for a, b in Input: 
    if not a in visited: 
        visited.add(a) 
        Output.append((a, b)) 
  
# Printing 
print("Initial list of tuple is \n", Input) 
print("List of tuple after removing duplicates:\n ", Output) 

Output:

Initial list of tuple is
[(12.121, ‘Geeksforgeeks is best’), (19212.22, ‘India is best’), (12.121, ‘Cyware is best.’), (923232.2323, ‘Jiit is best’)]

List of tuple after removing duplicates:
[(12.121, ‘Geeksforgeeks is best’), (19212.22, ‘India is best’), (923232.2323, ‘Jiit is best’)]

Method #2: Using list comprehension

# Python code to remove tuples having  
# duplicate first value from given 
# list of tuples 
  
# Input list initialization 
Input = [(12.121, 'Geeksforgeeks is best'),  
         (19212.22, 'India is best'),  
         (19212.22, 'Cyware is best.'),  
         (923232.2323, 'Jiit is best')] 
  
# Using set 
seen = set() 
  
# using list comprehension 
Output = [(a, b) for a, b in Input 
         if not (a in seen or seen.add(a))] 
  
# Printing 
print("Initial list of tuple is" \n, Input) 
print("\nList of tuple after removing duplicates \n", Output) 

Output:

Initial list of tuple is
[(12.121, ‘Geeksforgeeks is best’), (19212.22, ‘India is best’), (19212.22, ‘Cyware is best.’), (923232.2323, ‘Jiit is best’)]

List of tuple after removing duplicates [(12.121, ‘Geeksforgeeks is best’), (19212.22, ‘India is best’), (923232.2323, ‘Jiit is best’)]

Method #3: Using itertools

# Python code to remove tuples having  
# duplicate first value from given 
# list of tuples 
  
import itertools 
  
# Input list initialization 
Input = [(12.121, 'Geeksforgeeks is best'),  
         (19212.22, 'India is best'),  
         (923232.2323, 'Cyware is best.'),  
         (923232.2323, 'Jiit is best')] 
  
# Using groupby 
Output = ([next(b) for a, b in itertools.groupby( 
                         Input, lambda y: y[0])]) 
  
# Printing 
print("Initial list of tuple is\n", Input) 
print("\nList of tuple after removing duplicates\n", Output) 

Output:

Initial list of tuple is
[(12.121, ‘Geeksforgeeks is best’), (19212.22, ‘India is best’), (923232.2323, ‘Cyware is best.’), (923232.2323, ‘Jiit is best’)]

List of tuple after removing duplicates
[(12.121, ‘Geeksforgeeks is best’), (19212.22, ‘India is best’), (923232.2323, ‘Cyware is best.’)]

Method #4: Using OrderedDict

This is the most elegant way to remove duplicates is using OrderedDict.

# Python code to remove tuples having  
# duplicate first value from given 
# list of tuples 
  
from collections import OrderedDict 
  
# Input list initialization 
Input = [(12.121, 'Geeksforgeeks is best'),  
         (19212.22, 'India is best'),  
         (19212.22, 'Cyware is best.'),  
         (923232.2323, 'Jiit is best')] 
  
# Using orderedDIct 
Output = OrderedDict(Input).items() 
  
# Printing 
print("Initial list of tuple is\n", Input) 
print("\nList of tuple after removing duplicates\n", Output) 

Output:

Initial list of tuple is
[(12.121, ‘Geeksforgeeks is best’), (19212.22, ‘India is best’), (19212.22, ‘Cyware is best.’), (923232.2323, ‘Jiit is best’)]

List of tuple after removing duplicates
odict_items([(12.121, ‘Geeksforgeeks is best’), (19212.22, ‘Cyware is best.’), (923232.2323, ‘Jiit is best’)])

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