[Rd] Proposal unary - operator for factors

[William Dunlap]

> -----Original Message-----
> From: r-devel-bounces at r-project.org 
> [mailto:r-devel-bounces at r-project.org] On Behalf Of Hadley Wickham
> Sent: Wednesday, February 03, 2010 3:10 PM
> To: r-devel at r-project.org
> Subject: [Rd] Proposal unary - operator for factors
> 
> Hi all,
> 
> Why not make the unary minus operator return the factor with levels
> reversed?  This would make it much easier to sort factors in
> descending order in part of an order statement.

It wouldn't make sense in the context of
   vector[-factor]

Wouldn't it be better to allow order's decreasing argument
to be a vector with one element per ... argument?  That
would work for numbers, factors, dates, and anything
else.  Currently order silently ignores decreasing[2] and
beyond.

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com 

> 
> Hadley
> 
> -- 
> http://had.co.nz/
> 
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