Building a Dictionary with Default Values in Python: 5 Simple Examples to Follow

You can create a dictionary with default values using various methods in Python. Here are five examples:

1. Using a loop to initialize default values:

default_dict = {}
keys = ['a', 'b', 'c']
default_value = 0
for key in keys:
    default_dict[key] = default_value
print(default_dict)  # Output: {'a': 0, 'b': 0, 'c': 0}

2. Using a dictionary comprehension:

keys = ['a', 'b', 'c']
default_value = 0
default_dict = {key: default_value for key in keys}
print(default_dict)  # Output: {'a': 0, 'b': 0, 'c': 0}

3. Using dict.fromkeys() method:

keys = ['a', 'b', 'c']
default_value = 0
default_dict = dict.fromkeys(keys, default_value)
print(default_dict)  # Output: {'a': 0, 'b': 0, 'c': 0}

4. Using collections.defaultdict:

from collections import defaultdict
default_value = 0
default_dict = defaultdict(lambda: default_value)
print(default_dict)  # Output: defaultdict(<function <lambda> at 0x7f01137a8c20>, {})

5. Using collections.defaultdict with int as the default factory:

from collections import defaultdict
default_dict = defaultdict(int)
print(default_dict)  # Output: defaultdict(<class 'int'>, {})

All these examples will create dictionaries where every key is initialized with the same default value.