Hi,
?pairlist gives no explanation about what exactly is the difference
between a pairlist and a list (except that a pairlist of length 0
is 'NULL'). So, what's a pairlist?
class(.Options)
[1] "pairlist"
Some strange things about the "pairlist" type:
> showClass("pairlist")
Error in getClass(Class) : "pairlist" is not a defined class
Why the above doesn't work? It works for "list":
> showClass("list")
No Slots, prototype of class "list"
Extends: "vector"
> is.list(.Options)
[1] TRUE
> is.vector(.Options)
[1] FALSE
This doesn't make sense! If 'x' is a list, then it should be considered
a vector too.
Subsetting a pairlist with [] doesn't produce a pairlist:
> class(.Options[1:3])
[1] "list"
Yes, this one is documented, but still...
Cheers,
H.
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
