# Preface

This book started out as the class notes used in the HarvardX Data Science Series1.

A hardcopy version of the book is available from CRC Press2.

A free PDF of the October 24, 2019 version of the book is available from Leanpub3.

The R markdown code used to generate the book is available on GitHub4. Note that, the graphical theme used for plots throughout the book can be recreated using the ds_theme_set() function from dslabs package.