我想这个就可以了

if isinstance(obj, str)

要获取类型，使用__class__成员，如unknown_thing.__class__

Talk of duck-typing is useless here because it doesn't answer a perfectly good question. In my application code I never need to know the type of something, but it's still useful to have a way to learn an object's type. Sometimes I need to get the actual class to validate a unit test. Duck typing gets in the way there because all possible objects have the same API, but only one is correct. Also, sometimes I'm maintaining somebody else's code, and I have no idea what kind of object I've been passed. This is my biggest problem with dynamically typed languages like Python. Version 1 is very easy and quick to develop. Version 2 is a pain in the buns, especially if you didn't write version 1. So sometimes, when I'm working with a function I didn't write, I need to know the type of a parameter, just so I know what methods I can call on it.

这就是__class__参数派上用场的地方。这(据我所知)是获取对象类型的最佳方法(可能是唯一的方法)。

你很接近了!字符串是模块，不是类型。你可能想比较obj的类型和字符串的类型对象，即str:

type(obj) == str  # this works because str is already a type

另外:

type(obj) == type('')

注意，在python2中，如果obj是unicode类型，那么上述两种方法都不能工作。isinstance()也不会。看看约翰对这篇文章的评论，了解如何解决这个问题……我已经试着记住它大约10分钟了，但是有一个记忆块!

isinstance()

在你的例子中，isinstance("this is a string"， str)将返回True。

你可能还想读这个:http://www.canonical.org/~kragen/isinstance/

使用str代替string

type ( obj ) == str

解释

>>> a = "Hello"
>>> type(a)==str
True
>>> type(a)
<type 'str'>
>>>

使用isinstance(object, type)。如上所述，如果你知道正确的类型，这很容易使用，例如，

isinstance('dog', str) ## gives bool True

但对于更深奥的对象，这可能很难使用。 例如:

import numpy as np 
a = np.array([1,2,3]) 
isinstance(a,np.array) ## breaks

但你可以用这个技巧:

y = type(np.array([1]))
isinstance(a,y) ## gives bool True 

所以我建议用你想检查的对象类型(例如，type(np.array())实例化一个变量(在本例中是y)，然后使用isinstance。