Modules, Libraries, & Packages

Key Terms

Understanding the vocabulary helps you know what you're importing and why:

• Script — A .py file you run to automate a task
• Module — A .py file containing reusable functions, classes, or variables that other scripts can import
• Package — A folder (directory) containing multiple related modules, installed via pip
• Library — A broad term for a collection of modules that extend what Python can do

Importing a Module

# Import the entire module — access functions with module.function()
import math
result = math.sqrt(16)       # 4.0

# Import only a specific function — use it directly without the prefix
from math import sqrt
result = sqrt(16)

# Import with an alias — useful for long module names
import math as m
result = m.sqrt(16)

Listing What's Available in a Module

If you want to see all the functions available in a module, use dir():

import math
print(dir(math))    # prints a list of everything in the math module

Getting Help on Any Function or Module

The help() function displays the built-in documentation for anything in Python:

help(print)         # Shows docs for the print() function
help(str.split)     # Shows docs for the string split() method

import os
help(os)            # Shows full documentation for the os module

Useful Built-in Modules (No Install Needed)

These come with Python and are always available:

import os           # File system operations: paths, directories, running commands
import re           # Regular expressions for pattern matching in strings
import json         # Read and write JSON data
import csv          # Read and write CSV files
import ipaddress    # Work with IP addresses and subnets
import datetime     # Work with dates and times
import math         # Mathematical functions (sqrt, floor, ceil, etc.)
import filecmp      # Compare files and directories

The ipaddress Module — Network Automation Example

import ipaddress

# Create a network object and iterate over all hosts in the subnet
network = ipaddress.ip_network("192.0.2.0/24")
for host in network.hosts():
    print(host)
# Automatically skips network address and broadcast address

Installing Third-Party Packages with pip

pip is Python's package manager. Use it in your terminal/command line to install packages from the internet:

pip install netmiko      # SSH connections to network devices
pip install requests     # HTTP/API calls
pip install pandas       # Data analysis
pip install paramiko     # SSH protocol
pip install boto3        # AWS automation

Common Network Automation Libraries

Library	Purpose
Netmiko	SSH connections to routers, switches, firewalls
NAPALM	Interact with multiple network device OS types
Paramiko	Low-level SSHv2 implementation
Requests	Make HTTP requests to REST APIs
Scapy	Craft, send, and receive network packets
Boto3	Amazon Web Services (AWS) automation
Pandas	Data analysis, CSV/Excel file processing