The argument I have in 'The R Inferno'
is that how you want to combine factors
may differ from someone else's desires.
There are lots of tricky questions:
What about ordered factors?
What if the ordered levels are different in
different objects?
...
Pat
On 04/02/2010 15:53, Hadley Wickham wrote:
Hi all,
Is there are reason that there is no c.factor method? Analogous to
c.Date, I'd expect something like the following to be useful:
c.factor<- function(...) {
factors<- list(...)
levels<- unique(unlist(lapply(factors, levels)))
char<- unlist(lapply(factors, as.character))
factor(char, levels = levels)
}
c(factor("a"), factor("b"), factor(c("c", "b","a")), factor("d"))
# [1] a b c b a d
# Levels: a b c d
Hadley
--
Patrick Burns
pbu...@pburns.seanet.com
http://www.burns-stat.com
(home of 'The R Inferno' and 'A Guide for the Unwilling S User')
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