Data Science from Scratch, 2nd Edition

Preface to the Second Edition

I am exceptionally proud of the first edition of Data Science from Scratch. It turned out very much the book I wanted it to be. But several years of developments in data science, of progress in the Python ecosystem, and of personal growth as a developer and educator have changed what I think a first book in data science should look like.

In life, there are no do-overs. In writing, however, there are second editions.

Accordingly, I’ve rewritten all the code and examples using Python 3.6 (and many of its newly introduced features, like type annotations). I’ve woven into the book an emphasis on writing clean code. I’ve replaced some of the first edition’s toy examples with more realistic ones using “real” datasets. I’ve added new material on topics such as deep learning, statistics, and natural language processing, corresponding to things that today’s data scientists are likely to be working with. (I’ve also removed some material that seems less relevant.) And I’ve gone over the book with a fine-toothed comb, fixing bugs, rewriting explanations that are less clear than they could be, and freshening up some of the jokes.

The first edition was a great book, and this edition is even better. Enjoy!

• Joel Grus
• Seattle, WA
• 2019

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Using Code Examples

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Acknowledgments

First, I would like to thank Mike Loukides for accepting my proposal for this book (and for insisting that I pare it down to a reasonable size). It would have been very easy for him to say, “Who’s this person who keeps emailing me sample chapters, and how do I get him to go away?” I’m grateful he didn’t. I’d also like to thank my editors, Michele Cronin and Marie Beaugureau, for guiding me through the publishing process and getting the book in a much better state than I ever would have gotten it on my own.

I couldn’t have written this book if I’d never learned data science, and I probably wouldn’t have learned data science if not for the influence of Dave Hsu, Igor Tatarinov, John Rauser, and the rest of the Farecast gang. (So long ago that it wasn’t even called data science at the time!) The good folks at Coursera and DataTau deserve a lot of credit, too.

I am also grateful to my beta readers and reviewers. Jay Fundling found a ton of mistakes and pointed out many unclear explanations, and the book is much better (and much more correct) thanks to him. Debashis Ghosh is a hero for sanity-checking all of my statistics. Andrew Musselman suggested toning down the “people who prefer R to Python are moral reprobates” aspect of the book, which I think ended up being pretty good advice. Trey Causey, Ryan Matthew Balfanz, Loris Mularoni, Núria Pujol, Rob Jefferson, Mary Pat Campbell, Zach Geary, Denise Mauldin, Jimmy O’Donnell, and Wendy Grus also provided invaluable feedback. Thanks to everyone who read the first edition and helped make this a better book. Any errors remaining are of course my responsibility.

I owe a lot to the Twitter #datascience commmunity, for exposing me to a ton of new concepts, introducing me to a lot of great people, and making me feel like enough of an underachiever that I went out and wrote a book to compensate. Special thanks to Trey Causey (again), for (inadvertently) reminding me to include a chapter on linear algebra, and to Sean J. Taylor, for (inadvertently) pointing out a couple of huge gaps in the “Working with Data” chapter.

Above all, I owe immense thanks to Ganga and Madeline. The only thing harder than writing a book is living with someone who’s writing a book, and I couldn’t have pulled it off without their support.