[R] Arguments to order()

[David Neu]

Hi,

The rows of a data frame can be sorted lexicographically as shown in
this example,

my.df <- data.frame(x=c(1,1,1,2,2), y=c(1,2,3,2,1))
my.df[order(my.df$x,my.df$y, decreasing=TRUE), ]

however, I'm wondering if it's possible to pass a variable in as the
first argument to order() so that the actual set of columns used in
the sort can be easily varied?

FWIW, the first argument to order() is of type "..." and page 2 of R
Language Manual says that "Users cannot easily get hold of objects of"
this type.

Many thanks for any ideas!

Cheers,
Dave