Did you leave out the warning from "+", which should be an error,
as it produces an illegal ordered factor in this case and factor+factor
is nonsensical? Or is the warning missing in the current development
version of R?
> x <- factor("A", ordered=FALSE) + factor(c("B","C"), ordered=TRUE)
Warning message:
Incompatible methods ("Ops.factor", "Ops.ordered") for "+"
> str(x) # 2 levels, so integer codes of 3 is illegal
ordered[1:2] w/ 2 levels B<C: 2 3
Bill Dunlap
TIBCO Software
wdunlap tibco.com
On Mon, Mar 30, 2015 at 1:10 PM, Hadley Wickham <h.wick...@gmail.com> wrote:
> This is admittedly a contrived example, but...
>
> data(housing, package ="MASS")
> x <- housing$Type + housing$Sat
> match(x, unique(x))
>
> Hadley
>
> --
> http://had.co.nz/
>
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