How to apply same function to every specified column in a data.table

Question

I have a data.table with which I\'d like to perform the same operation on certain columns. The names of these columns are given in a character vector. In this particular ex

Answer 1

I would like to add an answer, when you would like to change the name of the columns as well. This comes in quite handy if you want to calculate the logarithm of multiple columns, which is often the case in empirical work.

cols <- c("a", "b")
out_cols = paste("log", cols, sep = ".")
dt[, c(out_cols) := lapply(.SD, function(x){log(x = x, base = exp(1))}), .SDcols = cols]