data science / r

R for Data Science, Free

R is the language built by statisticians, for statistics — unmatched for analysis, modeling, and visualization. Learn it from the definitive free book and an interactive in-console tutorial. All resources free and current.

While Python dominates general data science, R remains the tool of choice for statistics-heavy work, academic research, and gorgeous visualization (via ggplot2). It's especially strong if your background is stats or you work with tabular data. The two resources below are the canonical free starting points — one a complete book, the other a hands-on tutorial you run inside R itself.