The default initialization for slots of class "factor" and
"data.frame" gives NULL. This seems odd, since those slots can't
ever
be set to NULL by the user. I would expect zero-length instances of
factor and data.frame.
Here is an example:
setClass("FOO", representation(a="factor",
b="data.frame", c="numeric"))
[1] "FOO"> ff <- new("FOO")
> ff
An object of class "FOO"
Slot "a":
NULL
Slot "b":
NULL
Slot "c":
numeric(0)
sessionInfo()
R version 2.3.0, 2005-12-26, powerpc-apple-darwin8.3.0
attached base packages:
[1] "tools" "methods" "stats"
"graphics" "grDevices" "utils"
[7] "datasets" "base"
Slot c is initialized as I was expecting.
+ seth
you might need a call to "setOldClass"; see Section "Register or Convert?" of the corresponding help page. Matthias Seth Falcon schrieb:>The default initialization for slots of class "factor" and >"data.frame" gives NULL. This seems odd, since those slots can't ever >be set to NULL by the user. I would expect zero-length instances of >factor and data.frame. > >Here is an example: > >setClass("FOO", representation(a="factor", b="data.frame", c="numeric")) >[1] "FOO" > > >>ff <- new("FOO") >>ff >> >> >An object of class "FOO" >Slot "a": >NULL > >Slot "b": >NULL > >Slot "c": >numeric(0) > > >sessionInfo() >R version 2.3.0, 2005-12-26, powerpc-apple-darwin8.3.0 > >attached base packages: >[1] "tools" "methods" "stats" "graphics" "grDevices" "utils" >[7] "datasets" "base" > > >Slot c is initialized as I was expecting. > >+ seth > >______________________________________________ >R-devel at r-project.org mailing list >https://stat.ethz.ch/mailman/listinfo/r-devel > >-- StaMatS - Statistik + Mathematik Service Dipl.Math.(Univ.) Matthias Kohl Gottlieb-Keim-Stra?e 60 95448 Bayreuth Phone: +49 921 50736 457 E-Mail: matthias.kohl at stamats.de www.stamats.de