[EMAIL PROTECTED] wrote:
Hi. I don't know if this a bug or just annoying to me:
x <- c(1,2,3,NA)
table(x, exclude=NULL)
x
1 2 3 <NA>
1 1 1 1
table(factor(x), exclude=NULL)
1 2 3
1 1 1
I don't think many people use factor(x, exclude=NULL): it is not the
default handling of character data by read.table().
Cheers, David Duffy.
I've moved this to "wishlist" in the bug repository. It's a documented
annoyance, but we might be able to do better.
The underlying issue is the following:
> f <- factor(c(1:3,NA),labels=letters[3:1])
> f
[1] c b a <NA>
Levels: c b a
> factor(f)
[1] c b a <NA>
Levels: c b a
> factor(f,exclude=NULL)
[1] c b a <NA>
Levels: c b a <NA>
> factor(f,levels=levels(f),exclude=NULL)
[1] c b a <NA>
Levels: c b a
> factor(f,levels=c(levels(f),NA),exclude=NULL)
[1] c b a <NA>
Levels: c b a <NA>
and this code in table() suggests that the latter is what was intended
(since we actually try to pass exclude=NULL):
cat <- if (is.factor(a)) {
if (!missing(exclude)) {
ll <- levels(a)
factor(a, levels = ll[!(ll %in% exclude)], exclude = if
(is.null(exclude))
NULL
else NA)
}
else a
(levels = if(is.null(exclude)) c(ll,NA) else ll[!(ll %in% exclude)]
should do. This will change behaviour of the case where you have mixed
factors and non-factors, so I'm not just implementing it right away.
--
O__ ---- Peter Dalgaard Øster Farimagsgade 5, Entr.B
c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907
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