"Think Stats: Exploratory Data Analysis with Python" (or "Think Stats: Probability and Statistics for Programmers) is an excellent introductory book on statistics, probability and data analysis written by Allen B. Downey. The book is easy to read and its project-based approach demystifies harder statistical concepts. As the title suggests, the book is heavily based on the use of Python and the author makes his code and data available in the book's Github repository.
The goal of this project is to allow R users (or people interested in the R language) to also benefit from this masterpiece. This is a side project and I am not working on it full-time. The book is available for free: