Importing Modules

A module is useful when you can use its code in another file.

Python uses import for this.

What Does Import Mean?

Import means bringing code from another module into your program.

After importing, you can use functions, variables, or classes from that module.

Basic Import

import math

Now you can use the math module.

Example: square root

import math

print(math.sqrt(25))

Output

5.0

Import Your Own Module

If you created:

tools.py

With:

def hello():
    print("Hello")

Use it in another file:

import tools

tools.hello()

Output

Hello

Import Specific Item

Use from ... import ...

from math import sqrt

print(sqrt(16))

Output

4.0

Now you do not need math. before sqrt.

Import Multiple Items

from math import sqrt, pi

print(sqrt(9))
print(pi)

Output

3.0
3.141592653589793

Use an Alias

An alias is a shorter name.

import math as m

print(m.sqrt(36))

Output

6.0

Why Use Aliases?

Helpful when names are long.

Example:

import pandas as pd

Common Beginner Errors

Wrong File Name

The module name must match the file name.

File Not in Same Folder

Your file should be in the same project folder (for now).

Misspelled Function Name

Check spelling carefully.

Code Along

Import random.

Use:

random.randint(1, 10)

Mini Challenge

Create:

numbers.py

Add:

def triple(n):
    return n * 3

Import it and print:

15

Real World Use Case

Projects import modules for math, files, APIs, data tools, web apps, and reusable code.

Quiz

1. What does import do?
2. What is the difference between import math and from math import sqrt?
3. What is an alias?
4. Why do we import modules?

Assignment

Create your own module with one function and import it using an alias.

Summary

You learned how to import modules, import specific items, and use aliases in Python.