What are the methods for checking data types in python?

The methods for viewing data types in python are: 1. type() function; 2. isinstance() function; 3. dir() function; 4. hasattr() function; 5. isinstance() function and type () function comparison; 6. collections module. Detailed introduction: 1. type() function, which is the most basic data type checking method. It can return the type of an object; 2. isinstance() function, this function can check an object and so on.

The operating system for this tutorial: Windows 10 system, Python version 3.11.4, DELL G3 computer.

In Python, there are multiple ways to view data types. The following are some common methods:

1. type(): This is the most basic data type checking method. It can return the type of an object. For example:

x = 10  
print(type(x))  # <class &#39;int&#39;>  
  
y = &#39;hello&#39;  
print(type(y))  # <class &#39;str&#39;>

2. isinstance(): This function can check whether an object is a given type. For example:

x = 10  
print(isinstance(x, int))  # True  
  
y = 'hello'  
print(isinstance(y, str))  # True

Please note that the isinstance() function can also check whether the object is one of certain types, such as a list or dictionary. For example:

x = [1, 2, 3]  
print(isinstance(x, (list, tuple)))  # True  
  
y = {'name': 'Alice', 'age': 25}  
print(isinstance(y, dict))  # True

3. dir(): This function can return a list of all properties and methods of an object. By looking at this list, you can learn what type an object is. For example:

x = [1, 2, 3]  
print(dir(x))  # A list of x's attributes and methods.

4. hasattr(): This function can check whether an object has specific attributes or methods. For example:

x = [1, 2, 3]  
print(hasattr(x, '__getitem__'))  # True, because all list objects have this method.

5. Comparison of isinstance() and type(): Although both can be used to check Python's data type, it is usually recommended to use isinstance(). This is because isinstance() is a safer function and can handle inheritance and multiple inheritance situations, while type() cannot. At the same time, isinstance() is also a more commonly used function, which is more robust in handling possible exceptions. For example, if you try to use type() to check for an attribute that doesn't exist, Python will throw an AttributeError. If you use isinstance(), this problem will not occur. For example:

class MyClass:  
    pass  
  
obj = MyClass()  
print(hasattr(obj, 'non_existent_attribute'))  # False, as expected.  
print(hasattr(obj, 'non_existent_attribute'))  # Raises AttributeError.

6. Collections module: Python’s collections module contains a series of abstract base classes that define various types of interfaces. For example, Counter, defaultdict, OrderedDict, etc. are all part of this module. By looking at the definitions of these classes, you can learn about the properties and methods of various data types in Python. For example: collections.Counter is a dictionary subclass used to count hashable objects. Its initialization method accepts an iterable object as a parameter and then counts each element. You can learn how it works by looking at its source code.

The above is the detailed content of What are the methods for checking data types in python?. For more information, please follow other related articles on the PHP Chinese website!