collections.defaultdict()
CollectionsA dict subclass that calls a factory function for missing keys.
Signature
defaultdict(default_factory)
Returns
defaultdictExample
from collections import defaultdict
d = defaultdict(list)
d['fruits'].append('apple')
d['fruits'].append('banana')
print(d) # {'fruits': ['apple', 'banana']}About collections.defaultdict()
collections.defaultdict is a Python collections function with the signature defaultdict(default_factory). A dict subclass that calls a factory function for missing keys. It returns a value of type defaultdict.
Python provides a rich set of built-in functions and standard library modules that cover common programming tasks. Understanding these functions helps you write more idiomatic, efficient Python code. The collections.defaultdictfunction is commonly used in data processing, web development, scripting, and automation tasks.
When working with collections.defaultdict(), consider edge cases like empty inputs, None values, and type mismatches. Python's duck typing means many built-in functions work with any object that implements the required protocol (e.g., __len__ for len(), __iter__ for iteration). This flexibility is a key strength of Python's design philosophy.