Python Importing Modules

In Python, modules are a way to organize and reuse code. Importing modules allows you to access a module’s functions, classes, and variables in your program. In this tutorial, we’ll learn how to import built-in modules, import specific functions or classes, and even create and use custom modules.

1. What is a Python Module?

A Python module is a file with a .py extension that contains Python code—such as functions, classes, and variables. Modules allow you to logically organize your Python programs and reuse code across different programs.

2. Importing a Python Module

To use the functions and variables in a module, you need to import it. The most basic way to import a module is by using the import statement:

Example: Importing a Built-in Module

import math

result = math.sqrt(16)
print(result)

Here, we import the math module and use its sqrt() function to calculate the square root of 16.

3. Importing Specific Functions or Classes from a Module

If you only need specific functions or classes from a module, you can import them directly using the from keyword. This avoids the need to reference the module name every time you call a function or class.

Example: Importing Specific Functions

from math import sqrt

result = sqrt(16)
print(result)

Here, we import the sqrt() function directly from the math module, so we don’t need to reference math.sqrt() each time.

4. Renaming a Module on Import

You can rename a module when importing it using the as keyword. This is especially useful when dealing with long module names or to avoid name conflicts.

Example: Renaming a Module

import math as m

result = m.sqrt(16)
print(result)

In this example, we import the math module and rename it as m. Now we can reference the module with the shorter name m.

5. Importing All Functions from a Module

Another way to import a module is by importing everything from the module. This allows you to directly access all functions, classes, and variables without needing to reference the module name.

Example: Importing All Functions

from math import *

result = sqrt(16)
print(result)

Here, we import everything from the math module, so we can use the sqrt() function directly without referencing math.sqrt().

6. Importing from a Custom Module

In addition to built-in modules, you can also create your own custom modules. A custom module is just a Python file containing functions or classes that you want to reuse in other scripts.

Example: Creating a Custom Module

# my_module.py
def add(a, b):
    return a + b

Now, you can import and use the add() function from your custom module in another Python file.

Example: Using a Custom Module

import my_module

result = my_module.add(5, 3)
print(result)

In this example, we import the my_module module and call the add() function defined inside it.

7. Importing from a Module in a Different Directory

If your module is located in a different directory, you can specify its path using the sys.path variable or by modifying the PYTHONPATH environment variable.

Example: Importing from a Different Directory

import sys
sys.path.append('/path/to/your/module/directory')

import my_module

In this example, we add the directory containing our custom module to the system path, allowing us to import the module from that location.

Conclusion

Importing modules is a powerful way to organize and reuse code in Python. You can import built-in modules, specific functions or classes, and even your custom modules to make your programs more modular and efficient.