Check your understanding
Quiz
You have finished the data.table section: its syntax and keys, how it compares with dplyr, bigger-than-memory data, and dtplyr. This quiz checks what stuck. The last two steps are live R.
Question 1 of 8
The data.table template
In the DT[i, j, by] template, the j slot is for:
Correct: j says what to do with the columns.
data.table syntax has no file slot.