Exercise

A non-existing column

Have a close look at 1.1 and 1.2 from the data.table package FAQs.

Type D <- 5 in the console. What do you think is the output of DT[, .(D)] and DT[, D]?

Instructions

50 XP

Possible Answers

Both outputs give an error.
DT[, D] returns 5 as vector, and DT[, .(D)] returns 5 as data.table.
DT[, D] returns 5 as data.table, and DT[, .(D)] returns 5 as vector.
DT[, D] returns 5 as vector, and DT[, .(D)] returns an error.
DT[, D] returns an error, and DT[, .(D)] returns 5 as data.table.

Take Hint (-15 XP)