Book Image

The Python Workshop

By : Olivier Pons, Andrew Bird, Dr. Lau Cher Han, Mario Corchero Jiménez, Graham Lee, Corey Wade
Book Image

The Python Workshop

By: Olivier Pons, Andrew Bird, Dr. Lau Cher Han, Mario Corchero Jiménez, Graham Lee, Corey Wade

Overview of this book

Have you always wanted to learn Python, but never quite known how to start? More applications than we realize are being developed using Python because it is easy to learn, read, and write. You can now start learning the language quickly and effectively with the help of this interactive tutorial. The Python Workshop starts by showing you how to correctly apply Python syntax to write simple programs, and how to use appropriate Python structures to store and retrieve data. You'll see how to handle files, deal with errors, and use classes and methods to write concise, reusable, and efficient code. As you advance, you'll understand how to use the standard library, debug code to troubleshoot problems, and write unit tests to validate application behavior. You'll gain insights into using the pandas and NumPy libraries for analyzing data, and the graphical libraries of Matplotlib and Seaborn to create impactful data visualizations. By focusing on entry-level data science, you'll build your practical Python skills in a way that mirrors real-world development. Finally, you'll discover the key steps in building and using simple machine learning algorithms. By the end of this Python book, you'll have the knowledge, skills and confidence to creatively tackle your own ambitious projects with Python.
Table of Contents (13 chapters)

Default Dictionary

The built-in dictionary type considers it to be an error when you try to access the value for a key that doesn't exist. It will raise a KeyError, which you have to handle or your program crashes. Often, that's a good idea. If the programmer doesn't get the key correct, it could indicate a typo or a misunderstanding of how the dictionary is used.

It's often a good idea, but not always. Sometimes, it's reasonable that a programmer doesn't know what the dictionary contains; whether it's created from a file supplied by the user or the content of a network request, for example. In situations like this, any of the keys the programmer expects could be missing, but handling KeyError instances everywhere will be tedious, repetitive, and make the intent of the code harder to see.

For these situations, Python provides the collections.defaultdict type. It works like a regular dictionary, except that you can give it a function that creates...