all Python 3Dictionaries (dict)function

dict.keys

iteration

Return a dynamic view of the dict's keys.

Syntax

d.keys()

The view is live, not a snapshot: add or drop a key after view = d.keys() and both the view and its len() follow the dict. So mutating the dict inside for k in d.keys() raises RuntimeError — iterate over a list(d.keys()) copy instead. Also, plain for k in d already walks the keys, so spelling out .keys() buys nothing.

Examples

d = {'a': 1, 'b': 2}
print(list(d.keys()))   # → ['a', 'b']
view = d.keys()
d['c'] = 3
print(list(view))       # → ['a', 'b', 'c'] (view динамичен)

See also

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