Flatten a nested list
Flatten arbitrarily nested lists and tuples into a single flat iterator, leaving strings intact.
- Python
- GreenSnippets
- MIT
- Executed with Python 3.11
from collections.abc import Iterable
def flatten(items):
for item in items:
if isinstance(item, Iterable) and not isinstance(item, (str, bytes)):
yield from flatten(item)
else:
yield itemExample / expected output
list(flatten([1, [2, (3, [4])], "ab"])) # [1, 2, 3, 4, 'ab']How it works
A recursive generator yields items lazily, so huge structures are not copied. Strings and bytes are iterable but must be treated as single values, otherwise they would be split into characters forever.
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