Define the subtraction operation of two objects using Python's __sub__() function

Title: Using Python's __sub__() function to define the subtraction operation of two objects

Python is a concise and efficient programming language, with special methods Allows us to customize the behavior of objects. In this article, we will learn how to use the __sub__() function in Python to define the subtraction operation between two objects. Through sample code, we will show how to overload the subtraction operator so that our objects can be subtracted.

Python's special methods begin and end with double underscores, and they define behavior related to built-in operators and functions. For the subtraction operation, we need to use the special method __sub__() to define the behavior when two objects are subtracted.

Let us use an example to illustrate how to define the subtraction operation of two objects. Suppose we have a custom class called Vector that represents a two-dimensional vector. We want to be able to subtract two vectors and get a new vector.

The following is the definition of the Vector class:

class Vector:
    def __init__(self, x, y):
        self.x = x
        self.y = y

    def __sub__(self, other):
        return Vector(self.x - other.x, self.y - other.y)

    def __str__(self):
        return f"Vector({self.x}, {self.y})"

In the above code, we define a Vector class with two attributes, x and y. The __sub__() method accepts another vector as a parameter, calculates the difference between the two vectors, and returns a new Vector object.

Next, let’s use the Vector class for an example of subtraction:

v1 = Vector(3, 4)
v2 = Vector(1, 2)

v3 = v1 - v2
print(v3)  # 输出：Vector(2, 2)

In the above example, we created two Vector objects v1 and v2, representing the vectors (3, 4 ) and (1, 2). Then, we subtract v1 and v2 by using the subtraction operator "-" and assign the result to v3. Finally, we print v3, and the result is a new Vector object (2, 2), which represents vector (3, 4) minus vector (1, 2).

By using the __sub__() special method, we define the subtraction operation between two objects, making our Vector class have the function of subtraction operation.

To summarize, using Python's __sub__() function can easily define the subtraction operation between two objects. We only need to implement the __sub__() method in the class to handle the subtraction logic of the two objects and return a new object. This way we can customize the object's behavior to suit our programming needs.

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