Module 10 Study Guide – Introduction to Python

Key Terms

Module: A Python file (.py) containing functions, classes, and variables that can be reused through importing.

Standard Library: The collection of modules that come built into Python (math, random, datetime, etc.).

pip: Python's package installer for downloading and installing third-party packages from PyPI.

PyPI: Python Package Index - an online repository of over 400,000 community-created Python packages.

Virtual Environment: An isolated Python environment where packages are installed separately from the system Python.

Dot Notation: Using module.function() to access items inside a module.

Alias: A shorter name for a module created with import module as alias.

The math module provides sqrt(), ceil(), floor(), and the constant pi
ceil() rounds up, floor() rounds down
The random module provides randint(), choice(), and shuffle()
shuffle() modifies the list in place and returns None
The datetime module provides now() for current date/time and strftime() for formatting

import math              # Use as: math.sqrt(16)
from math import sqrt    # Use as: sqrt(16)
import math as m         # Use as: m.sqrt(16)

Avoid from module import * - it causes naming conflicts
Python only runs module code once even with multiple imports
Place imports at the top of your file in this order: standard library, third-party, your own modules

1. What is the difference between import math and from math import sqrt?

2. Why should you avoid from module import *?

3. What happens when Python encounters an import statement for a module that was already imported?

4. What is the purpose of if __name__ == "__main__":?

5. When would you use a virtual environment?

6. What is the difference between pip install and import?

Forgetting to import a module before using it
Using math.sqrt() after from math import sqrt (use just sqrt())
Running pip commands inside a Python file instead of the terminal
Naming your file the same as a module (e.g., math.py conflicts with the built-in math module)
Forgetting that random.shuffle() returns None
Using parentheses with math.pi (it is a constant, not a function)