我怎么知道我的变量是什么类型的？

I don't know how to determine type of a given variable while I read Python code. I would like to know the types of variables without the deep knowledge of methods that initialize values for them. Say, I have piece of code:

我在阅读Python代码时不知道如何确定给定变量的类型。我想知道变量的类型，而没有深入了解为它们初始化值的方法。说，我有一段代码：

import numpy as np

np.random.seed(0)
n = 10000
x = np.random.standard_normal(n)
y = 2.0 + 3.0 * x + 4.0 * np.random.standard_normal(n)
xmin = x.min()
xmax = x.max()
ymin = y.min()
ymax = y.max()

How do I know what type x is? In Java it's simple. Even if I don't know the method, I know the variable type.

我怎么知道x是什么类型的？在Java中它很简单。即使我不知道方法，我也知道变量类型。

5 个解决方案

#1

You can use the builtin type function to check the type of a variable.

您可以使用内置类型函数来检查变量的类型。

import numpy as np

np.random.seed(0)
n = 10000
x = np.random.standard_normal(n)
print(type(x))
# numpy.ndarray

If, in the specific case of numpy, you want to check the type of your elements, then you can do

如果，在numpy的特定情况下，您想要检查元素的类型，那么您可以这样做

print(x.dtype)
# dtype('float64')

#2

Python is a dynamically typed language. Technically, when reading code, you won't be able to know the type of a variable without following the code, or if the code is excessively simple.

Python是一种动态类型语言。从技术上讲，在阅读代码时，如果不遵循代码，或者代码过于简单，您将无法知道变量的类型。

A few quotes for you:

给你一些报价：

Python is strongly typed as the interpreter keeps track of all variables types. It's also very dynamic as it rarely uses what it knows to limit variable usage.

Python是强类型的，因为解释器会跟踪所有变量类型。它也非常动态，因为它很少使用它所知道的来限制变量的使用。

In Python, it's the program's responsibility to use built-in functions like isinstance() and issubclass() to test variable types and correct usage.

在Python中，程序有责任使用内置函数（如isinstance（）和issubclass（）来测试变量类型和正确使用。

You can use isinstance(x, type) or type(x) to learn about the variables type information at runtime.

您可以使用isinstance（x，type）或type（x）来了解运行时的变量类型信息。

#3

type(x) is straitforward answer. Normally you don't test type it through type but use isinstance(x, type) to test it.

type（x）是一个明确的回答。通常，您不测试通过类型键入它，但使用isinstance（x，type）来测试它。

#4

Use dtype:

使用dtype：

n = 10000
x = np.random.standard_normal(n)
x.dtype

gives:

得到：

dtype('float64')

---

If you want more detailed information on the array attributes, you could use info:

如果您想了解有关数组属性的更多详细信息，可以使用info：

np.info(x)

gives:

得到：

class:  ndarray
shape:  (10000,)
strides:  (8,)
itemsize:  8
aligned:  True
contiguous:  True
fortran:  True
data pointer: 0xba10c48
byteorder:  little
byteswap:  False
type: float64

#5

in the REPL (interactive console), you can also do

在REPL（交互式控制台）中，您也可以这样做

>>> help(x)

and it will display information about x's class, including it's methods.

它将显示有关x的类的信息，包括它的方法。