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

None of above solutions seems to work with calculation by group. Following is the best I got:

for(col in cols)
{
    DT[, (col) := scale(.SD[[col]], center = TRUE, scale = TRUE), g]
}