OrderedDict 的 (Im) 可变性

Question

Python 的 OrderedDict 数据结构是可变集合吗？

documentation没有说什么，在网上快速搜索后，我还没有找到任何答案。

Answer 1

Since OrderedDict is a mutable data structure, you can perform mutating operations on its instances. You can insert new items, update and remove existing items, and so on. If you insert a new item into an existing ordered dictionary, then the item is added to the end of the dictionary:

他们提供了几个 mutable 操作的例子，比如 insert:

>>> from collections import OrderedDict

>>> numbers = OrderedDict(one=1, two=2, three=3)
>>> numbers
OrderedDict([('one', 1), ('two', 2), ('three', 3)])

>>> numbers["four"] = 4
>>> numbers
OrderedDict([('one', 1), ('two', 2), ('three', 3), ('four', 4)])

一般来说，如果数据类型支持以下operations，则它被认为是可变序列类型。

Answer 2

OrderedDict 是可变的：

from collections import OrderedDict

d = OrderedDict.fromkeys('abcde')
d['a']= 'aretor'
print(d)

>> OrderedDict([('a', 'aretor'), ('b', None), ('c', None), ('d', None), ('e', None)])

print(d['a'])
>> aretor

Answer 3

The documentation does not say anything about it, and after a quick search on the web, I have not found any answer yet.

当对 class 的可变性有疑问时，您可以运行在测试

之后

from collections import OrderedDict
from collections.abc import MutableSequence, MutableSet, MutableMapping
print(issubclass(OrderedDict,(MutableSequence,MutableSet,MutableMapping)))

输出

True

请参阅 collections.abc 文档中的 Collections Abstract Base Classes 以了解可以通过这种方式检查的其他内容。

OrderedDict 的 (Im) 可变性

(Im)mutability of OrderedDict

python

python-3.x

ordereddict