I have a data frame, which looks like that:
P1 P2 P3 T1 T2 T3 I1 I2
1 2 3 5 52 43 61 6 \"b\"
2 6 4 3 72 NA 59 1 \"a\"
3
I used this code to produce your desired output. Is this what you were after?
rum <- read.table(textConnection("P1 P2 P3 T1 T2 T3 I1 I2
2 3 5 52 43 61 6 b
6 4 3 72 NA 59 1 a
1 5 6 55 48 60 6 f
2 4 4 65 64 58 2 b"), header = TRUE)
rum$I2 <- as.character(rum$I2)
rum[order(rum$I1, rev(rum$I2), decreasing = TRUE), ]
P1 P2 P3 T1 T2 T3 I1 I2
1 2 3 5 52 43 61 6 b
3 1 5 6 55 48 60 6 f
4 2 4 4 65 64 58 2 b
2 6 4 3 72 NA 59 1 a