@ Symbol in Python

@ Symbol in Python

  1. Use the @ Symbol in Decorators in Python
  2. Use the @ Symbol to Multiply Matrices in Python

The most common use case of the @ symbol in Python is in decorators. A decorator lets you change the behavior of a function or class.

The @ symbol can also be used as a mathematical operator, as it can multiply matrices in Python. This tutorial will teach you to use Python’s @ symbol.

Use the @ Symbol in Decorators in Python

A decorator is a function accepting a function as an argument, adding some functionalities to it, and returning the modified function.

For example, see the following code.

def decorator(func):
    return func
@decorator
def some_func():
    pass

This is equivalent to the code below.

def decorator(func):
    return func

def some_func():
    pass

some_func = decorator(some_func)

A decorator modifies the original function without altering any script in the original function.

Let’s see a practical example of the above code snippet.

def message(func):
    def wrapper():
        print("Hello Decorator")
        func()
    return wrapper


def myfunc():
    print("Hello World")

The @ symbol is used with the name of the decorator function. It should be written at the top of the function that will be decorated.

@message
def myfunc():
	print("Hello World")
myfunc()

Output:

Hello Decorator
Hello World

The above decorator example does the same work as this code.

def myfunc():
    print("Hello World")
myfunc = message(myfunc)
myfunc()

Output:

Hello Decorator
Hello World

Some commonly used decorators in Python are @property, @classmethod, and @staticmethod.

Use the @ Symbol to Multiply Matrices in Python

From Python 3.5, the @ symbol can also be used as an operator to perform matrix multiplication in Python.

The following example is a simple implementation of multiplying matrices in Python.

class Mat(list):
    def __matmul__(self, B):
        A = self
        return Mat([[sum(A[i][k]*B[k][j] for k in range(len(B)))
                    for j in range(len(B[0])) ] for i in range(len(A))])

A = Mat([[2,5],[6,4]])
B = Mat([[5,2],[3,5]])
print(A @ B)

Output:

[[25, 29], [42, 32]]

That’s it. The @ symbols in Python are used in decorators and matrix multiplications.

You should now understand what the @ symbol does in Python. We hope you find this tutorial helpful.

Rohan Timalsina avatar Rohan Timalsina avatar

Rohan is a learner, problem solver, and web developer. He loves to write and share his understanding.

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