Python modules, packages and pip

Modules: toolboxes you can import

A module is a Python file full of ready-made functions and values. Python ships with hundreds of them (the *standard library*), and you can install thousands more.

• A module is one .py file.
• A package is a folder of modules.
• pip is the tool that downloads and installs packages from the internet.

Three ways to import

import math                       # 1. the whole module; use math.sqrt()
print(math.sqrt(49))

from math import sqrt, pi         # 2. only some names; use sqrt() directly
print(sqrt(49), pi)

import datetime as dt             # 3. a short nickname (alias)
print(dt.date.today())

Avoid from math import *: it pulls in every name and can silently replace your own variables.

The math module

import math
r = 7
print(f"Area of the circle: {math.pi * r ** 2:.2f}")

The random module

import random
print(random.randint(1, 6))               # dice roll: 1 to 6, both included
print(random.random())                    # a float from 0.0 up to (not including) 1.0
print(random.choice(["Asha", "Ravi"]))    # one random item
names = ["A", "B", "C", "D"]
random.shuffle(names)                     # shuffles the list in place
print(random.sample(range(1, 50), 6))     # 6 different numbers

Example: a 4-digit OTP.

otp = random.randint(1000, 9999)
print("Your OTP is", otp)

The datetime module

from datetime import date, datetime

today = date.today()
print(today)                              # 2026-10-29
print(today.strftime("%d/%m/%Y"))         # 29/10/2026

exam = date(2027, 3, 1)
print((exam - today).days, "days left")   # subtracting dates gives a timedelta

now = datetime.now()
print(now.strftime("%I:%M %p"))           # 05:42 PM

Make your own module

Save functions in a file, for example school_utils.py:

# school_utils.py
def grade(marks):
    return "Pass" if marks >= 33 else "Fail"

SCHOOL = "Model School"

Then import it from another file in the same folder:

# main.py
import school_utils
print(school_utils.grade(45), school_utils.SCHOOL)

if __name__ == "__main__"

Code at the bottom of a module runs when the module is imported. To run test code only when the file is run directly, put it under this check:

if __name__ == "__main__":
    print(grade(50))      # runs for 'python school_utils.py', not for 'import school_utils'

pip: install packages from the internet

Run pip in a terminal (Command Prompt), not inside Python:

pip install tabulate
pip list
pip uninstall tabulate

Then use the package:

from tabulate import tabulate
rows = [["Asha", 91], ["Ravi", 78]]
print(tabulate(rows, headers=["Name", "Marks"]))

If pip is not found, try python -m pip install tabulate.

Common mistakes

• Naming your own file random.py or math.py: Python imports your file instead of the real module.
• Typing pip install inside the Python shell: it is a terminal command.
• ModuleNotFoundError: the package is not installed, or it was installed for a different Python.
• Forgetting the module name: after import math, write math.sqrt(), not sqrt().

Key points

• import module, from module import name, and import module as alias are the three import styles.
• math, random and datetime come with Python; nothing to install.
• Any .py file can be imported as a module from the same folder.
• pip install name adds third-party packages.

Practice questions

import random
a, b = random.randint(1, 6), random.randint(1, 6)
print(a, b, "total", a + b)

from datetime import date
born = date(2010, 5, 14)
print((date.today() - born).days)