Reorder rows in data.table in a specific order

Question

I have a data.table dumdt:

set.seed(123)
dumdt <- data.table(v1=sample(1:10, 5), v2=1:5)

whose rows I\'d like to r

Answer 1

If I understand correctly, you can just add a col and then order by it:

setorder(dumdt[, .r := order(to_ord)], .r)[, .r := NULL]

   v1 v2
1:  4  3
2:  6  5
3:  8  2
4:  3  1
5:  7  4