[R] Sorting in R

[Peter Dalgaard BSA]

Jim Robison-Cox <jimrc at gauss.math.montana.edu> writes:

> On Wed, 21 Jun 2000, Art Salwin wrote:
> 
> > Having secondary keys to break ties would be nice, as would
> > the ability to sort (in this example)
> > all 3 vectors at once.
> 
>  That's a bit harder,  I would sort first on the secondary column, then
> the primary.  Or tertiary - secondary - primary.
> 
>  If primary is name, secondary age, tertiary zip:
> spsheet <- spsheet[order(zip),]
> spsheet <- spsheet[order(age),]
> spsheet[order(name),]
>  
>   I hope someone has a better way.

Indeedy:

spsheet[order(name,age,zip),]

Two things (well really the same thing) that R is not good at:

(a) sorting descending
(b) alternate collating sequence

(a) works for numeric vectors (order(-x)) but not character. One might
consider having an ordering-function argument, defaulting to "<"



-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
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