Modules

Intermediate Python for Developers

Jasmin Ludolf

Senior Data Science Content Developer

What are modules?

Modules are Python scripts
- Files ending with .py
- Contain functions and attributes
- Can contain other modules

Help us avoid rewriting code that already exists!

Man looking at reflection, seeing further reflections

Python modules

There are around 200 built-in modules
- Documentation

os:
- Used for interacting with our operating system
- Check the current directory
- List available files
- Access environment variables
string:
- Simplifies text processing tasks

Python modules

Importing a module

# General syntax
import <module_name>

# Import the os module
import os

# Check the type
print(type(os))

<class 'module'>

Finding a module's functions

Check the documentation

# Call help()
# Warning - will return a very large output!
print(help(os))

Help on module os:

NAME
    os - OS routines for NT or Posix depending on what system we're on.

MODULE REFERENCE
    https://docs.python.org/3.12/library/os.html
    ...

Getting the current working directory

# Using an os function
print(os.getcwd())

/home/courses/intermediate_python_for_developers

Useful if we need to reference the directory later

# Assign to a variable
work_dir = os.getcwd()

Changing directory

# Changing directory
os.chdir("/home/courses")

# Check the current directory
print(os.getcwd())

/home/courses

# Confirm work_dir has not changed
print(work_dir)

/home/courses/intermediate_python_for_developers

Module attributes

Attributes return values
Functions perform tasks
Don't use parentheses with attributes

# Get the local environment
print(os.environ)

environ{'PATH': '/usr/local/bin',
        'TERM': 'xterm',
        'HOSTNAME': '097a0fe4-d6ce-4325-a6e2-1d0ce2800c2b',
        'TZ': 'Europe/Brussels',
        'LANG': 'en_US.UTF-8',
         ...

String module

import string


print(string.ascii_lowercase)

abcdefghijklmnopqrstuvwxyz

Check if a string contains letters, numbers, or specific characters

Handy for validating user input 💡

print(string.digits)

0123456789

print(string.punctuation)

!"#$%&'()*+,-./:;<=>?@[\]^_`{|}~

Let's practice!

Intermediate Python for Developers