如何比较 Python 中的枚举?

2022-01-25 00:00:00 python python-3.x enums compare

问题描述

从 Python 3.4 开始，存在 Enum 类.

Since Python 3.4, the Enum class exists.

我正在编写一个程序，其中一些常量具有特定的顺序，我想知道哪种方式最适合比较它们:

I am writing a program, where some constants have a specific order and I wonder which way is the most pythonic to compare them:

class Information(Enum):
    ValueOnly = 0
    FirstDerivative = 1
    SecondDerivative = 2

现在有一种方法，需要将Information的给定information与不同的枚举进行比较:

Now there is a method, which needs to compare a given information of Information with the different enums:

information = Information.FirstDerivative
print(value)
if information >= Information.FirstDerivative:
    print(jacobian)
if information >= Information.SecondDerivative:
    print(hessian)

直接比较不适用于枚举，所以有三种方法，我想知道哪种方法更受欢迎:

The direct comparison does not work with Enums, so there are three approaches and I wonder which one is preferred:

方法一:使用价值观:

if information.value >= Information.FirstDerivative.value:
     ...

方法 2:使用 IntEnum:

Approach 2: Use IntEnum:

class Information(IntEnum):
    ...

方法 3:根本不使用枚举:

Approach 3: Not using Enums at all:

class Information:
    ValueOnly = 0
    FirstDerivative = 1
    SecondDerivative = 2

每种方法都有效，方法 1 有点冗长，而方法 2 使用不推荐的 IntEnum 类，而方法 3 似乎是在添加 Enum 之前这样做的方式.

Each approach works, Approach 1 is a bit more verbose, while Approach 2 uses the not recommended IntEnum-class, while and Approach 3 seems to be the way one did this before Enum was added.

我倾向于使用方法 1，但我不确定.

I tend to use Approach 1, but I am not sure.

感谢您的建议！

解决方案

我之前没有遇到过 Enum，所以我扫描了文档(https://docs.python.org/3/library/enum.html) ... 并找到了 OrderedEnum(第 8.13.13.2 节)这不是你想要的吗?来自文档:

I hadn'r encountered Enum before so I scanned the doc (https://docs.python.org/3/library/enum.html) ... and found OrderedEnum (section 8.13.13.2) Isn't this what you want? From the doc:

>>> class Grade(OrderedEnum):
...     A = 5
...     B = 4
...     C = 3
...     D = 2
...     F = 1
...
>>> Grade.C < Grade.A
True

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