如何检查我的python对象是否是数字? [英] How can I check if my python object is a number?

问题描述

在 Java 中，数字类型都从 Number 下降，所以我会使用

(x instanceof Number).

python 的等价物是什么?

解决方案

测试你的变量是否是 numbers.Number:

<预><代码>>>>进口号码>>>输入十进制>>>[isinstance(x, numbers.Number) for x in (0, 0.0, 0j, decimal.Decimal(0))][真、真、真、真]

这使用 ABCs 并将适用于所有内置 -在类似数字的类中，也适用于所有第三方类，如果它们值得的话(注册为 Number ABC 的子类).

但是，在许多情况下，您不必担心手动检查类型 - Python 是鸭子类型 和混合一些兼容的类型通常是有效的，但是当某些操作没有意义时它会发出错误消息 (4 - "1")，因此很少真正需要手动检查.这只是一个奖励.您可以在完成一个模块时添加它，以避免在实现细节上纠缠其他人.

这在 从 Python 2.6 开始有效.在旧版本上，您几乎只能检查一些硬编码类型.

In Java the numeric types all descend from Number so I would use

(x instanceof Number).

What is the python equivalent?

解决方案

Test if your variable is an instance of numbers.Number:

>>> import numbers
>>> import decimal
>>> [isinstance(x, numbers.Number) for x in (0, 0.0, 0j, decimal.Decimal(0))]
[True, True, True, True]

This uses ABCs and will work for all built-in number-like classes, and also for all third-party classes if they are worth their salt (registered as subclasses of the Number ABC).

However, in many cases you shouldn't worry about checking types manually - Python is duck typed and mixing somewhat compatible types usually works, yet it will barf an error message when some operation doesn't make sense (4 - "1"), so manually checking this is rarely really needed. It's just a bonus. You can add it when finishing a module to avoid pestering others with implementation details.

This works starting with Python 2.6. On older versions you're pretty much limited to checking for a few hardcoded types.

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