Paul Lemmens <[EMAIL PROTECTED]> writes:
> Hello!
>
> If I read ?subset, the workings of the argument drop (to me) seem to
> imply equivalence of A and B (R 1.9.0):
>
> #A
> dd <- data.frame(rt=rnorm(10), c=factor(gl(2,5)))
> dd <- subset(dd, c==1)
> dd$c <- dd$c[, drop=TRUE]
> table(dd$c)
>
> 1
> 5
>
>
> #B
> dd <- data.frame(rt=rnorm(10), c=factor(gl(2,5)))
> dd <- subset(dd, c==1, drop=TRUE)
> table(dd$c)
>
> 1 2
> 5 0
>
> So to lose the second level of dd$c, in method B I still need to 'dd$c
> <-
> dd$c[, drop=TRUE]', while the manual seems to imply that with the drop
> argument to subset() this would not be necessary.
>
>
> Could you comment?
Looks like a documentation bug. The actual code ends up doing
x[r, vars, drop = drop]
and "[.data.frame" will not drop factor levels. I wonder if it ever
did...
--
O__ ---- Peter Dalgaard Blegdamsvej 3
c/ /'_ --- Dept. of Biostatistics 2200 Cph. N
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907
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