Elegantly assigning multiple columns in data.table with lapply()

Question

I am trying to figure out an elegant way to use := assignment to replace many columns at once in a data.table by applying a shared function. A typi

Answer 1

These should work if you want to refer to the columns by string name:

n = paste0("V", 20:100)
dt[, (n) := lapply(n, function(x) {sqrt(get(x))})]

or

dt[, (n) := lapply(n, function(x) {sqrt(dt[[x]])})]