Learn Python Basics

What Are Libraries?

A library is a collection of functions that can be added to your Python code and called as necessary, just like any other function. There is no reason to rewrite code that will perform a standard task. With libraries, you can import pre-existing functions and efficiently expand the functionality of your code.

Some examples of popular libraries and their functionalities:

• Requests: an elegant and simple HTTP library for Python, commonly used for REST API calls. (See my other course, Build Your Web Projects With REST APIs, to learn more! 😉 )

• Beautiful Soup: a library for pulling data out of HTML and XML files.  

• Pandas: a fast, powerful, and easy-to-use open-source data analysis and manipulation tool. 

There are thousands of Python libraries that you can use in your Python code!

Install Libraries Using Pip

Pip is a Python package manager.

A package manager is a tool that allows you to install and manage additional libraries through your terminal. Pip comes ready to go with a Python installation, so you’re already good to go!

To install a package using pip in your terminal, we use the following pattern:

pip install <name-of-package>

To view the packages already installed, you can type the following:

pip freeze

That will print a list of all the existing libraries, or dependencies, to your terminal.

Check out the screencast below to learn more about installing and viewing your Python packages using pip!

Import Libraries in Your Code

To import library functionality into your code, use the keyword import. (Shocker, right? 😄 )

Using the  import  keyword at the top of your code file, you can import certain library functions or the entire library at once. For example, to import the entire requests library, you must first install requests using your terminal with  pip install requests . Then you can write the following code in your text editor: 

import requests

 Now to call the get() function in the requests library, write:

requests.get()

If you want to import just one function named  get  from the requests library, write the following:

from requests import get

Now you don’t need to type requests before  get()  because the method itself has already been imported.

Level Up: Import Python Libraries

Context:

In this exercise, you will explore the concept of importing modules to enhance the calculator you previously developed. The goal is to group the calculation functionalities into a separate function, which will allow for better code organization and more efficient reuse of calculation functionalities in other parts of the program. You will learn how to import this calculation function into the main program, enabling you to use the calculation functionalities in a more modular and efficient manner.

Instructions:

• In the module named  operations.py  , add the following functions:

  • addition(a, b): which returns the sum of two numbers a and b;

  • multiplication(a, b) : which returns the product of two numbers a and b.

• In the main file, import the  operations.py module and use its functions to perform the following mathematical operations:

  • Addition of 10 and 5;

  • Multiplication of 8 and 4.

• Display the results of the operations in the console.

Once you have completed the exercise, you can run the following command in the VS code terminal  pytest tests.py.

Let’s Recap!

• A library is a collection of existing functions that can be used in your code. 

• Pip is a Python package manager that lets you install and manage your external libraries. 

• The import keyword lets you import entire libraries or specific library functions into your code.

Nice, you’ve learned how to import libraries using pip! Next, you’ll learn how to use these libraries to extract web data. Exciting stuff, right?