Book Image

Dancing with Python

By : Robert S. Sutor
Book Image

Dancing with Python

By: Robert S. Sutor

Overview of this book

Dancing with Python helps you learn Python and quantum computing in a practical way. It will help you explore how to work with numbers, strings, collections, iterators, and files. The book goes beyond functions and classes and teaches you to use Python and Qiskit to create gates and circuits for classical and quantum computing. Learn how quantum extends traditional techniques using the Grover Search Algorithm and the code that implements it. Dive into some advanced and widely used applications of Python and revisit strings with more sophisticated tools, such as regular expressions and basic natural language processing (NLP). The final chapters introduce you to data analysis, visualizations, and supervised and unsupervised machine learning. By the end of the book, you will be proficient in programming the latest and most powerful quantum computers, the Pythonic way.
Table of Contents (29 chapters)
Part I: Getting to Know Python
PART II: Algorithms and Circuits
PART III: Advanced Features and Libraries
Other Books You May Enjoy
Appendix C: The Complete UniPoly Class
Appendix D: The Complete Guitar Class Hierarchy
Appendix F: Production Notes

6.4 Return values

A Python function can return nothing, one thing, or many things. That covers all possibilities!

In truth, a Python function always returns one object. Let me explain. Our simple do-nothing function from the beginning of this chapter appears to produce nothing.

def f():

But if we check the type of the result, we see that it is NoneType.

f() is None

The returned object is None, which we discussed in section 3.9.5. We get the same result if we use a bare return in f.

def f():
f() is None

Use return to have the function pass a value back to whatever called the function.

def g(x, y):
    return x + y

g(10, 23)

If you forget the return, you will get None.

def bad_g(x, y):
    x + y

bad_g(10, 23) is None

It’s a common mistake for coders to...