R help - Apr 2011 - Arguments to order()

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

On 11-04-23 2:00 PM, David Neu wrote:
> 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?
Use do.call() to construct the call.

Duncan Murdoch
>
> 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
>
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