See how to join two data sets by one or more common columns using base R’s merge function, dplyr join functions, and the speedy data.table package.

R data.table code becomes more efficient — and elegant — when you take advantage of its special symbols and functions. With that in mind, we’ll look at some special ways to subset, count ...

A two-way table shows the frequency of data which satisfies two variables. Each row represents one variable, and each column represents another.