Assume I have the following input:
items = [1, 2, [3, 4], (5, 6), 'ciao', range(3), (i for i in range(3, 6))]
and I want to perform some recursive operation on items
.
For the sake of simplicity, let's say I want to flatten items (but could be anything else), one way of doing this would be:
def flatten(items, shallow=(str, bytes, bytearray)):
for item in items:
if isinstance(item, shallow):
yield item
else:
try:
yield from flatten(item)
except TypeError:
yield item
this would produce:
print(list(flatten(items)))
[1, 2, 3, 4, 5, 6, 'ciao', 0, 1, 2, 3, 4, 5]
Now how could I modify flatten()
so that I could produce the following (for arbitrary nesting levels)?
print(list(flatten(items)))
[1, 2, 3, 4, 5, 6, 'c', 'i', 'a', 'o', 0, 1, 2, 3, 4, 5]
只需在浅检查旁边添加一个长度检查:
if isinstance(item, shallow) and len(item) == 1:
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