R data.table apply function to rows using columns as arguments

Question

I have the following data.table

x = structure(list(f1 = 1:3, f2 = 3:5), .Names = c(\"f1\", \"f2\"), row.names = c(NA, -3L), class = c(\"data.tab         


        

Answer 1

The most elegant way I've found is with mapply:

x[, value := mapply(func.text, f1, f2)]
x
#    f1 f2    value
# 1:  1  3 21.08554
# 2:  2  4 56.59815
# 3:  3  5 151.4132

Or with the purrr package:

x[, value := purrr::pmap(.(f1, f2), func.text)]