(Leads to: Parsing details, Basic pivoting)
A tidy data frame is a data frame (or tibble) where the variables are in the columns, and the cases (or observations) are in the rows. All the of the built-in datasets that you’ve worked with so far have been tidy, but you’ll soon encounter new datasets that need to be tidied before you can work with them.
Introduction [r4ds-12.1]
Tidy data [r4ds-12.2]