6 1 Importing Modules Explained

Key Concepts

Importing modules in Python allows you to use code from other files or libraries. The key concepts include:

• Importing Standard Modules
• Importing Specific Functions
• Aliasing Modules
• Importing from Packages
• Creating and Importing Custom Modules

1. Importing Standard Modules

Python comes with a set of standard modules that provide additional functionality. You can import these modules using the import statement.

Example:

import math

result = math.sqrt(16)
print(result)  # Output: 4.0
    

Analogy: Think of a toolbox where you can pick a specific tool (module) to perform a task (function).

2. Importing Specific Functions

Instead of importing the entire module, you can import specific functions from a module using the from ... import ... statement.

Example:

from math import sqrt

result = sqrt(16)
print(result)  # Output: 4.0
    

Analogy: Think of a toolbox where you only take the specific tool (function) you need, not the entire toolbox.

3. Aliasing Modules

You can give a module or function an alias using the as keyword to make it easier to reference in your code.

Example:

import math as m

result = m.sqrt(16)
print(result)  # Output: 4.0
    

Analogy: Think of a toolbox where you label a tool (module) with a shorter name for easier access.

4. Importing from Packages

Packages are collections of modules. You can import modules from packages using the from ... import ... statement.

Example:

from datetime import datetime

now = datetime.now()
print(now)  # Output: Current date and time
    

Analogy: Think of a toolbox (package) containing multiple smaller toolboxes (modules).

5. Creating and Importing Custom Modules

You can create your own modules by writing Python code in a file and then importing it into another script.

Example:

Create a file named mymodule.py with the following content:

# mymodule.py
def greet(name):
    return f"Hello, {name}!"
    

Then, in another script, import and use the custom module:

import mymodule

message = mymodule.greet("Alice")
print(message)  # Output: Hello, Alice!
    

Analogy: Think of creating your own toolbox (module) and using it in your projects.

Putting It All Together

By understanding and using these import techniques effectively, you can leverage existing code and create modular, reusable Python programs.

Example:

import math as m
from datetime import datetime
import mymodule

result = m.sqrt(16)
print(result)  # Output: 4.0

now = datetime.now()
print(now)  # Output: Current date and time

message = mymodule.greet("Alice")
print(message)  # Output: Hello, Alice!