Here are some resources from outside of this course that will probably be useful in learning R.

I'm also creating an online course on exploratory data analysis together with DataCamp, an interactive platform to learn R and data science.

Try R: an free interactive in-browser tutorial

Twotorials: a series of two-minute videos introducing R

ggplot2 docs Documentation and detailed examples of all ggplot2 functions

Introduction to the data.table package in R: a tutorial that goes far beyond the discussion of data.table in Lesson 4.

Tidy Data: An excellent paper that lays out an essential guide to shaping your data to make manipulation, analysis and visualization easy

The R Inferno: an amusing guide to some of R's more surprising traps.

R Packages A tutorial to writing and publishing your own R packages

knitr: An R package for producing reproducible reports that integrate R with LaTeX or markdown.

Shiny Easily create interactive web visualizations using R

Bioconductor: A repository of R packages for analyzing genomic data, including genome sequencing and expression analysis.