Improve your skills at viewing data types in Python

Data type viewing skills in Python

In Python programming, accurately understanding data types is very important for data processing. Python provides a variety of methods to view data types, helping us to be more efficient and accurate when writing programs. This article will introduce several commonly used data type viewing techniques, with specific code examples.

1. Use the type() function to view basic data types

The built-in type() function in Python can return the data type of a given variable. By passing the variable to be viewed as a parameter to the type() function, the specific data type of the variable can be returned. The following is a sample code:

x = 5
y = "Hello World"
z = [1, 2, 3, 4, 5]

print(type(x))    # 输出<class 'int'>
print(type(y))    # 输出<class 'str'>
print(type(z))    # 输出<class 'list'>

In this example, we define an integer, a string and a list respectively. Through the type() function, we can see that x is of type int, y is of type str, and z is of type list.

2. Use the isinstance() function to check the inheritance relationship

Sometimes we need to determine whether the type of an object is an instance of a certain class, so we need to use the isinstance() function. The isinstance() function can determine whether an object is an instance of a specified class or a subclass of the specified class. The following is a sample code:

class Animal:
    def eat(self):
        print("Animal is eating...")

class Dog(Animal):
    def bark(self):
        print("Dog is barking...")

class Cat(Animal):
    def meow(self):
        print("Cat is meowing...")

dog = Dog()
cat = Cat()

print(isinstance(dog, Dog))     # 输出True
print(isinstance(cat, Animal))  # 输出True
print(isinstance(cat, Dog))     # 输出False

In this example, we define an Animal class, and then define the Dog and Cat classes, which are all subclasses of the Animal class. By using the isinstance() function, we can determine that dog is an instance of the Dog class and cat is an instance of the Animal class, but not an instance of the Dog class.

3. Use the dir() function to view object attributes and methods

In addition to having their own data types, objects in Python can also have attributes and methods. The dir() function can return a list of all properties and methods contained in an object. We can use the dir() function to view all properties and methods of an object to better understand the functionality of the object. The following is a sample code:

class Student:
    def __init__(self, name, age):
        self.name = name
        self.age = age

    def study(self):
        print("Student is studying...")

    def sleep(self):
        print("Student is sleeping...")

s = Student("Alice", 18)

print(dir(s))

In this example, we define a Student class, which contains two attributes: name and age, and two methods: study() and sleep(). By using the dir() function, we can see the list of all properties and methods of the s object.

Through these data type viewing techniques, we can better understand and use data types in Python and improve programming efficiency and accuracy. I hope the code examples in this article can be helpful to everyone in your study and work.

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