vector(type="logical", length=0) as.vector(x,mode="any") is.vector(x)
vector produces a vector of the given length and type.
Logical vector elements are initialized to
FALSE, numeric vector elements to 0
and character vector elements to "".
as.vector attempts to coerce its argument
into a vector of mode mode
(the default is to coerce to whichever mode is most convenient).
The attributes of x are removed.
is.vector returns TRUE if x
is a vector (of mode logical, factor, integer, real or character) and
FALSE otherwise.