r - passing variables as data.table column names

Question

The more I use it, the more data.table is replacing dplyr as my \'goto\' package as the speed it offers is a big plus.

Question

Answer 1

We can use eval(as.name(..

dt[eval(as.name(myCol[1]))> eval(as.name(myCol[2]))]

Or we can specify it in the .SDcols

dt[dt[, .I[.SD[[1]]> .SD[[2]]], .SDcols= myCol]]

Or an option using get by @thelatemail

dt[get(myCol[1]) > get(myCol[2])]

If there are only two elements, we can also use Reduce with mget (a slight variation of @thelatemail's answer)

dt[Reduce('>', mget(myCol))]