How to create a dictionary with default values in Python?

There are multiple ways to create a dictionary with default values in Python. Here are a few approaches:

Using a defaultdict: The defaultdict class from the collections module allows you to set a default value for new keys. Here's an example:

from collections import defaultdict

default_val = 0  # Specify the default value

my_dict = defaultdict(lambda: default_val)

Now, when you access a key in my_dict that doesn't exist, it will be automatically initialized with the default value (here, 0).

Using a dictionary comprehension: You can use a dictionary comprehension to assign default values to all keys in a dictionary. Here's an example:

default_val = 0

my_dict = {key: default_val for key in some_list_of_keys}

Here, some_list_of_keys is a list containing all the keys for which you want to set default values.

Using the get() method: You can also use the get() method of a dictionary to retrieve values for existing keys and set default values for non-existent keys. Here's an example:

default_val = 0

my_dict = {}

my_dict.get('key', default_val)

This will either return the value associated with the 'key' if it exists or the default value (0) if it doesn't.

These are a few methods to create a dictionary with default values in Python. Choose the one that suits your specific use case and programming style.