dict.fromkeys() New dict from keys
Last updated: 2026-09-22
dict.fromkeys() New dict from keys
dict.fromkeys(iterable[, value]) creates a new dict from iterable keys with value (default None).
| Category | Dict Methods |
|---|---|
| Kind | Built-in Type Method |
| Python Version | all |
📝 Syntax
dict.fromkeys(iterable[, value])⚙️ Parameters
| iterable Required | An iterable supplying the keys (list, tuple, ...). |
|---|---|
| value Optional | The value assigned to every key; default None.（Default：None） |
Returns：A new dict with keys from iterable and all values set to value.
Mutates the original：No (returns a new object)
▶ Example
Edit the code, press Run, and see the result in the output panel:
Output：
{'a': 0, 'b': 0}
{'x': None, 'y': None}💡 Related Cases
More case studies coming soon — check back later.
❓ FAQ
QIs fromkeys an instance method or a class method?
AIt is a class method, called directly as dict.fromkeys(iterable) without creating a dict instance first.
QDo all keys share the same value object?
AYes! In dict.fromkeys(['a', 'b'], []), 'a' and 'b' point to the same list, so appending an element to one affects the other. To get independent lists, use a dict comprehension like {k: [] for k in keys}.
QWhat is the default value when value is not passed?
ANone by default: dict.fromkeys(['a', 'b']) gives {'a': None, 'b': None}.
