Sort (order) data frame rows by multiple columns

Question

I want to sort a data frame by multiple columns. For example, with the data frame below I would like to sort by column 'z' (descending) then by column 'b' (ascending):

dd <- data.frame(b = factor(c("Hi", "Med", "Hi", "Low"),        levels = c("Low", "Med", "Hi"), ordered = TRUE),       x = c("A", "D", "A", "C"), y = c(8, 3, 9, 9),       z = c(1, 1, 1, 2)) dd     b x y z 1  Hi A 8 1 2 Med D 3 1 3  Hi A 9 1 4 Low C 9 2 

Answer 1

You can use the order() function directly without resorting to add-on tools -- see this simpler answer which uses a trick right from the top of the example(order) code:

R> dd[with(dd, order(-z, b)), ]     b x y z 4 Low C 9 2 2 Med D 3 1 1  Hi A 8 1 3  Hi A 9 1 

Edit some 2+ years later: It was just asked how to do this by column index. The answer is to simply pass the desired sorting column(s) to the order() function:

R> dd[order(-dd[,4], dd[,1]), ]     b x y z 4 Low C 9 2 2 Med D 3 1 1  Hi A 8 1 3  Hi A 9 1 R>  

rather than using the name of the column (and with() for easier/more direct access).