How to sort a dataframe by column(s) in R

Question

I want to sort a dataframe by multiple columns in R. 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

With this (very helpful) function by Kevin Wright, posted in the tips section of the R wiki, this is easily achieved.

> sort(dd,by = ~ -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

Answer 2

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

Answer 3

Alternatively, using the package Deducer

library(Deducer)
dd<- sortData(dd,c("z","b"),increasing= c(FALSE,TRUE))

Answer 4

or you can use package doBy

library(doBy)
dd <- orderBy(~-z+b, data=dd)

Answer 5

if SQL comes naturally to you, sqldf handles ORDER BY as Codd intended.

Answer 6

In my R-profile, I have a function that makes sorting like this significantly easier.

esort <- function(x, sortvar, ...) {
attach(x)
x <- x[with(x,order(sortvar,...)),]
return(x)
detach(x)
}

For your example above it would be a nice and easy:

esort(dd, -z, b)