How do I pass names for new summary columns to data.table in a function?

Question

Say I want to create a function that calculates a summary dataset from a data.table in R, and I want to be able to pass the name of the new calculated variable in programmat

Answer 1

Courtesy of docendo discimus, you can use a named list created with setNames, like this:

groupMeans <- function(out.var, by.var, dat = dt) {
  return(dat[, setNames(list(mean(x)), out.var), by = by.var])  
}

groupMeans("group.means", "by.var")
#    by.var group.means
# 1:      a  -0.1159832
# 2:      b   0.2910531