Convert Two Lists into a Dictionary - Python

We are given two lists, we need to convert both of the list into dictionary. For example we are given two lists a = ["name", "age", "city"], b = ["Geeks", 30,"Delhi"], we need to convert these two list into a form of dictionary so that the output should be like {'name': 'Geeks', 'age': 30, 'city': 'Delhi'}. We can do this using methods like zip, dictionary comprehension , itertools.starmap. Let's implement these methods practically.

Using zip

Use zip to pair elements from two lists, where the first list provides the keys and second provides the values after that we convert the zipped object into a dictionary using dict() which creates key-value pairs.

{'name': 'Alice', 'age': 30, 'city': 'New York'}

Explanation:

• zip(a, b) pairs each element from list a with the corresponding element from list b, creating tuples of key-value pairs.
• dict() function is used to convert the zipped pairs into a dictionary where elements from a become the keys and elements from b become values

Using Dictionary Comprehension

Use dictionary comprehension to iterate over the pairs generated by zip(a, b), creating key-value pairs where elements from list a are the keys and elements from list b are the values. This creates the dictionary in a single concise expression.

{'name': 'Alice', 'age': 30, 'city': 'New York'}

Explanation:

• Dictionary comprehension iterates over pairs generated by zip(a, b), where each pair consists of a key from list a and a value from list b.
• For each pair the key-value pair is directly added to dictionary res in one concise expression.

Using a Loop

Iterate through both lists simultaneously using zip and for each pair, add the first element as the key and second as the value to the dictionary.

{'name': 'Alice', 'age': 30, 'city': 'New York'}

Explanation:

• An empty dictionary res is created, and zip(a, b) is used to iterate through both lists yielding pairs of keys and values.
• During each iteration, key from list "a" is added to the dictionary with its corresponding value from list "b"

Using itertools.starmap

Use itertools.starmap to apply a lambda function that takes two arguments (key and value) to each pair generated by zip(a, b). This creates key-value pairs and passes them directly into dict() to form dictionary.

{'name': 'Alice', 'age': 30, 'city': 'New York'}

Explanation:

• starmap applies a lambda function to each pair from zip(a, b), where each pair consists of a key and a value.
• lambda function returns the key-value pair (k, v) and dict() converts the results into a dictionary.

Related Articles:

• zip() in Python
• Python Dictionary Comprehension
• Python – Itertools.starmap()
• Python Lambda Functions