On Wed, 3 Feb 2010, Duncan Murdoch wrote:
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. :-)
The same logic as strxfrm.
Duncan Murdoch
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Brian D. Ripley, rip...@stats.ox.ac.uk
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