Class of data.table column

Question

I\'d like to know how to ascertain the class of a column in a data.table dt given a character vector w.

Reproducible example:

Answer 1

These seem to work in the way you want:

1. class(dt[[w]])
2. sapply(dt,class)

Also, doing 2 and then subsetting works for 1: sapply(dt,class)[w].