Modules

A module is a collection of Python code that can be imported for use in your code. When a module is imported, the code in the module is executed, which makes it possible to use the functions and variables defined in the module. Python includes several modules in its standard library and you can also create and install more. In this section, we will sample a few of the standard library modules so you can get a feel for how modules work.

Importing modules

We will be using the sys module in this section as an example. The sys module provides access to some variables such as the Python version and the current platform the code is running on.

To use a module, you must first import it. You can import a module using the import keyword. After importing a module, you can access its functions and variables by using the dot operator. For example, to print the current Python version, you can do the following:

import sys
print(sys.version)

If you only want to use a specific function or variable from a module, you can import it directly using the from keyword.

from sys import version

And if you want to import multiple functions or variables from a module, you can do the following:

from sys import version, platform

You can even change the name of what you are importing.

import sys as system
from sys import version as python_version
from sys import version, platform as sys_version, sys_platform

Exercise

Use the sys module to print the current Python version and platform.

The random module

The random module provides functions for generating random numbers amount other things. The randint function imported from a module. The randint function takes two integers as arguments and will return a random integer between the two numbers. For example, the following code will print a random number between 1 and 100, including 1 and 100.

from random import randint
print(randint(1, 100))

Exercise

Using randint create a random number x from 1 to 4. Then, print the number as a word. For example, if the number is 1, print one.

The math module

The math module is another useful module to know. It provides access to many mathematical functions and constants that you would find on a calculator. Such as math.pi.

import math
print(math.pi)

Exercise

Using the math modules sqrt function, print the square root of 90.

The os module

The os module provides access to functions that allow you to interact with the operating system, like working with files and directories. Another feature is the ability to read environment variables set by the operating system.

import os
print(os.getenv("PATH"))

Exercise

Using the os module, print the environment variables of the HOME directory