Understanding Python re(gex)?

Learn Python Regular Expressions step-by-step from beginner to advanced levels with hundreds of examples and exercises. The standard library re and the third-party regex module are covered in this book. Visit https://youtu.be/2x2n7ynamm8 for a short video about the book.

The book also includes exercises to test your understanding, which are presented together as a single file in this repo — Exercises.md.

For solutions to the exercises, see Exercise_solutions.md.

You can also use this interactive TUI app to practice most of the exercises from the book.

See Version_changes.md to keep track of changes made to the book.

E-book

You can purchase the pdf/epub versions of the book using these links:
- https://leanpub.com/py_regex
- https://learnbyexample.gumroad.com/l/py_regex
You can also get the book as part of these bundles:
- All books bundle bundle from https://leanpub.com/b/learnbyexample-all-books or https://learnbyexample.gumroad.com/l/all-books
- Learn by example Python bundle from https://leanpub.com/b/python-bundle or https://learnbyexample.gumroad.com/l/python-bundle
- Awesome Regex bundle from https://leanpub.com/b/regex or https://learnbyexample.gumroad.com/l/regex
See https://learnbyexample.github.io/books/ for a list of other books

For a preview of the book, see sample chapters.

The book can also be viewed as a single markdown file in this repo. See my blogpost on generating pdf/epub from markdown using pandoc if you are interested in the ebook creation process.

For the web version of the book, visit https://learnbyexample.github.io/py_regular_expressions/

Testimonials

I love your books on regex...As a student from the Digital VLSI space, it is indeed useful now and definitely in the future. It's really well written and really easy to understand the examples.

— feedback on reddit

Feedback and Contributing

⚠️ ⚠️ Please DO NOT submit pull requests. Main reason being any modification requires changes in multiple places.

I would highly appreciate it if you'd let me know how you felt about this book. It could be anything from a simple thank you, pointing out a typo, mistakes in code snippets, which aspects of the book worked for you (or didn't!) and so on. Reader feedback is essential and especially so for self-published authors.

You can reach me via:

Issue Manager: https://github.com/learnbyexample/py_regular_expressions/issues
E-mail: echo 'bGVhcm5ieWV4YW1wbGUubmV0QGdtYWlsLmNvbQo=' | base64 --decode
Twitter: https://twitter.com/learn_byexample

Table of Contents

Preface
Why is it needed?
re introduction
Anchors
Alternation and Grouping
Escaping metacharacters
Dot metacharacter and Quantifiers
Interlude: Tools for debugging and visualization
Working with matched portions
Character class
Groupings and backreferences
Interlude: Common tasks
Lookarounds
Flags
Unicode
regex module
Gotchas
Further Reading

Acknowledgements

Special thanks to Al Sweigart. His Automate the Boring Stuff book was instrumental for me to get started with Python.

License

The book is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

The code snippets are licensed under MIT, see LICENSE file.

License

learnbyexample/py_regular_expressions

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