Python Create Dictionary from List with Default Values

Dictionaries in Python are versatile data structures that allow you to store and retrieve key-value pairs efficiently. Sometimes, you may need to initialize a dictionary with default values based on a list of keys. In this article, we’ll explore some simple and commonly used methods to create a dictionary from a list with default values in Python.

Python Create Dictionary from List with Default Values

Below, are the methods of Python Create Dictionary from List with Default Values.

• Using a For Loop
• Using dict.fromkeys() Method
• Using a Dictionary Comprehension
• Using zip() Function

Python Create Dictionary from List with Default Values Using For Loop

In this example, the below code initializes a dictionary `result_dict` with keys from the list `keys` and sets each key’s value to the `default_value` (0). Finally, it prints the resulting dictionary.

Python3

keys = ['apple', 'banana', 'cherry']
default_value = 0

result_dict = {}
for key in keys:
    result_dict[key] = default_value

print(result_dict)

Output

{'apple': 0, 'banana': 0, 'cherry': 0}

Python Create Dictionary from List with Default Values Using dict.fromkeys() Method

In this example, below code creates a dictionary `result_dict` with keys from the list `keys`, and each key is assigned the `default_value` (0) using the `dict.fromkeys()` method. The resulting dictionary is then printed.

Python3

keys = ['apple', 'banana', 'cherry']
default_value = 0

result_dict = dict.fromkeys(keys, default_value)
print(result_dict)

Output

{'apple': 0, 'banana': 0, 'cherry': 0}

Python Create Dictionary from List with Default Values Using Dictionary Comprehension

In this example, below code utilizes a dictionary comprehension to create a dictionary `result_dict` with keys from the list `keys`, and each key is assigned the `default_value` (0). The resulting dictionary is then printed.

Python3

keys = ['apple', 'banana', 'cherry']
default_value = 0

result_dict = {key: default_value for key in keys}
print(result_dict)

Output

{'apple': 0, 'banana': 0, 'cherry': 0}

Python Create Dictionary from List with Default Values Using zip() Function

In this example, below code uses the `zip()` function to combine the list of keys (`keys`) with a list containing the `default_value` (0) repeated for each key. The resulting pairs are then used to create a dictionary named `result_dict`, which is printed afterward.

Python3

keys = ['apple', 'banana', 'cherry']
default_value = 0

result_dict = dict(zip(keys, [default_value] * len(keys)))
print(result_dict)

Output

{'apple': 0, 'banana': 0, 'cherry': 0}