On 03/02/2010 7:20 PM, Hadley Wickham wrote:
Currently, for numeric a you can do either
  order(-a)
or
  order(a, decreasing=FALSE)
For nonnumeric types like POSIXct and factors only
the latter works.

Under my proposal your
  order(a, -b, c, d)
would be
  order(a, b, c, d, decreasing=c(FALSE,TRUE,FALSE,TRUE))
and it would work for any ordably class without modifications
to any classes.
Why not use

 order(a, -xtfrm(b), c, -xtfrm(d))

That's a good suggestion.  You could make it even easier to read with
desc <- function(x) -xtfrm(x)

order(a, desc(b), c, desc(d))

Could you remind me what xtfrm stands for?

No, I don't think I ever worked it out. :-)

Duncan Murdoch

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