Python – Convert a list of Tuples into Dictionary

Last Updated : 21 Jan, 2025

We are given a list of tuples we need to convert that list in form of dictionary.
For example li=[(“a”, 1), (“b”, 2), (“c”, 3)] is a list containing multiple tuples and we need to convert this in dictionary so that the output should be like {‘a’: 1, ‘b’: 2, ‘c’: 3} . To do this we can use methods like dict, dictionary comprehension , map and various other methods.

Using dict()

dict() function converts an iterable of key-value pairs, such as a list of tuples, into a dictionary. It assigns the first element of each tuple as the key and the second as the corresponding value.

# List of tuples where each tuple represents a key-value pair
a = [("a", 1), ("b", 2), ("c", 3)]

# Convert the list of tuples into a dictionary
res = dict(a)

print(res)

Output

{'a': 1, 'b': 2, 'c': 3}

Explanation:

List a contains tuples, where each tuple consists of a key-value pair, such as (“a”, 1).
dict() function converts the list of tuples into a dictionary mapping each key to its corresponding value.

Using Dictionary Comprehension

Dictionary comprehension allows creating a dictionary in a single line by iterating over an iterable and specifying key-value pairs. It uses the syntax {key: value for item in iterable} to construct the dictionary efficiently.

# List of tuples where each tuple represents a key-value pair
a = [("a", 1), ("b", 2), ("c", 3)]

# Create a dictionary using dictionary comprehension, iterating over the pairs
res = {key: value for key, value in a}

print(res)

Output

{'a': 1, 'b': 2, 'c': 3}

Explanation:

List a contains tuples where each tuple has a key-value pair, such as (“a”, 1).
Dictionary comprehension is used to iterate through the list a and create a dictionary by assigning the first element of each tuple as the key and the second as the value.

Using `for` Loop

Using a for loop to create a dictionary involves iterating over an iterable and adding each element as a key-value pair. This can be done by manually assigning values to a dictionary within the loop.

a = [("a", 1), ("b", 2), ("c", 3)]

# Initialize an empty dictionary to store the result
res = {}

# Iterate through each tuple in the list, unpacking into 'key' and 'value'
for key, value in a:
    # Add the key-value pair to the dictionary
    res[key] = value

print(res)

Output

{'a': 1, 'b': 2, 'c': 3}

Explanation:

Code initializes an empty dictionary res and iterates over the list a, unpacking each tuple into key and value.
In each iteration, the key is used to assign the value to the res dictionary, building the dictionary step by step.

Using `map()` with `dict()`

map() function applies a given function to each element in an iterable, and when used with dict(), it transforms the result into key-value pairs. This allows for efficient mapping and conversion into a dictionary.

a = [("a", 1), ("b", 2), ("c", 3)]

# Use map to apply a lambda function to each tuple, creating key-value pairs
res = dict(map(lambda x: (x[0], x[1]), a))

print(res)

Output

{'a': 1, 'b': 2, 'c': 3}

Explanation:

map() function applies the lambda function to each tuple in the list a, which extracts the first and second elements as key-value pairs.
dict() function then converts the output of map() into a dictionary, resulting in key-value pairs like {'a': 1, 'b': 2, 'c': 3}.