Sort rows in data.table in decreasing order on string key `order(-x,v)` gives error on data.table 1.9.4 or earlier
Update
data.table v1.9.6+ now supports OP's original attempt and the following answer is no longer necessary.
You can use DT[order(-rank(x), y)].
x y v1: c 1 72: c 3 83: c 6 94: b 1 15: b 3 26: b 6 37: a 1 48: a 3 59: a 6 6
You can only use - on the numeric entries, so you can use decreasing and negate the ones you want in increasing order:
DT[order(x,-v,decreasing=TRUE),] x y v [1,] c 1 7 [2,] c 3 8 [3,] c 6 9 [4,] b 1 1 [5,] b 3 2 [6,] b 6 3 [7,] a 1 4 [8,] a 3 5 [9,] a 6 6
DT[order(-x)] works as expected. I have data.table version 1.9.4. Maybe this was fixed in a recent version.
Also, I suggest the setorder(DT, -x) syntax in keeping with the set* commands like setnames, setkey