What are and how to use modules in Python

Modules are files that contain code Python, which allow us to divide the code into multiple files in a way that makes it more organized and easier to reuse code.

A module in Python is simply a file with a .py extension that contains Python code (within this file, we can include definitions of functions, variables, classes, etc).

Creating a module

To create a module in Python, we simply create a file with a .py extension and write our code in it.

For example, we can create a module called operations.py with some mathematical operation functions:

# operations.py

def add(a, b):
    return a + b

def subtract(a, b):
    return a - b

def multiply(a, b):
    return a * b

def divide(a, b):
    if b != 0:
        return a / b
    else:
        return "Error: Division by zero"

Importing a Module

To use the functions and variables of a module in another Python file, we first need to import it.

We can import a complete module or import only the functions we need.

Importing a complete module

One way to import a module in another is to import it completely (which would import all the functions and definitions it contains)

import operations

result_add = operations.add(5, 3)
print("Result of the addition:", result_add)

result_subtract = operations.subtract(10, 4)
print("Result of the subtraction:", result_subtract)

Importing specific functions from a module

We can also import specific functions from a module (which can be useful if we only need a few functions and do not want to load the entire module).

from operations import multiply, divide

result_multiply = multiply(6, 2)
print("Result of the multiplication:", result_multiply)

result_divide = divide(15, 3)
print("Result of the division:", result_divide)

Aliases in Importing

We can also use aliases when importing modules or functions. This allows us to use a shorter or more convenient name in our code.

import operations as ops

result_add = ops.add(5, 3)
print("Result of the addition:", result_add)

from operations import subtract as subtract

result_subtract = subtract(10, 4)
print("Result of the subtraction:", result_subtract)

Standard Python Modules

In addition to creating our own modules, Python includes a standard library with a wide variety of useful modules for various tasks. Some examples are:

To use these modules, we simply import them in the same way we did with our own operations module.

Basic Example

In many cases, it is common to have a main file that acts as an entry point to our program. This file can import the necessary modules and execute the main code.

For example, let’s suppose we have a file main.py that imports and uses the functions from the operations module.

# main.py

import operations as ops

result_add = ops.add(5, 3)
print("Result of the addition:", result_add)

result_subtract = ops.subtract(10, 4)
print("Result of the subtraction:", result_subtract)