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

6.12 Recursion

A recursive function is one that calls itself. At first thought, this could be a problem because it might seem that the execution would never stop: the function would call itself, which would call itself, which would call itself, and so on. Indeed, this simple example function does just that:

def f(x):


Eventually, Python will give up and raise an error:

File "<stdin>", line 1, in <module>
File "<stdin>", line 1, in f
File "<stdin>", line 1, in f
File "<stdin>", line 1, in f
[Previous line repeated 996 more times]
RecursionError: maximum recursion depth exceeded

Python is saying: “Look, I tried doing the same thing a thousand times, but enough is enough, and you probably didn’t intend to do it.” The recursion depth can vary from system to system. In what follows, I assume it is 1,000.

I give...