2.3. Modules and Packages

Modules and Packages

Programming concept

A module is a collection of functions.

A package is a collection of modules.

The functions we have used so far are available in the Python Standard Library, which means they come automatically as part of your Python distribution. One can also have access to additional functions that are not part of the Python standard library which will provide us with more features that we can use in Python, such as creating plots. To do this we would need to import modules into our Python code.

import statements are normally placed as the first lines of code in your file, before the other code. The syntax to import modules is as follows:

import module_name
import package_name.module_name
import module_name as preferred_name
import package_name.module_name as preferred_name
from package_name import module_name as preferred_name

The third, fourth and fifth example, allows us to specify an alias or alternative name of our choosing to refer to the module. In choosing this preferred_name we need to be careful of name clashes with existing keywords, functions or variables. Once a module is imported, we would be able to access all the functions of this module in our code. Assuming our example module above contains a function called fun1(), after importing the module we can call fun1() from our code as following:

module_name.fun1() or preferred_name.fun1() if a preferred_name was specified when importing the module.

In this practical we will be looking into importing modules from two popular packages; matplotlib and numpy.