使用 Python 输入模块指定序列或列表的长度 [英] Specify length of Sequence or List with Python typing module

问题描述

我正在尝试 Python typing 模块.

I'm giving the Python typing module a shot.

我知道像下面这样指定 List 的长度是有效的*:

I know that it's valid to specify the length of a List like the following*:

List[float, float, float]   # List of 3 floats <-- NOTE: this is not valid Python

是否有更长列表的简写?如果我想将它设置为 10 个浮点数怎么办?

Is there any shorthand for longer lists? What if I want to set it to 10 floats?

List[float * 10]   # This doesn't work.

如果这是可能的任何想法，这会很方便.

Any idea if this is possible, this would be handy.

*注意:事实证明，以这种方式向 Sequence[](及其子类)提供多个参数目前不是有效的 Python.此外，目前无法以这种方式使用 typing 模块指定 Sequence 长度.

*NOTE: It turns out that supplying multiple arguments to Sequence[] (and its subclasses) in this manner is currently NOT valid Python. Furthermore, it is currently not possible to specify a Sequence length using the typing module in this way.

推荐答案

你不能.列表是可变的、可变长度结构.如果您需要固定长度的结构，请改用元组:

You can't. A list is a mutable, variable length structure. If you need a fixed-length structure, use a tuple instead:

Tuple[float, float, float, float, float, float, float, float, float, float]

或者更好的是，使用一个命名元组，它具有索引和命名属性:

Or better still, use a named tuple, which has both indices and named attributes:

class BunchOfFloats(NamedTuple):
    foo: float
    bar: float
    baz: float
    spam: float
    ham: float
    eggs: float
    monty: float
    python: float
    idle: float
    cleese: float

列表只是固定长度数据结构的错误数据类型.

A list is simply the wrong data type for a fixed-length data structure.

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