Achim,
you are right, in principle, but I think I'd rather expect that
as.vector(x1mat, mode = "list")
also removes the dim attributes.
Uwe
Achim Zeileis wrote:
On Sun, 17 Oct 2004 01:51:47 +0000 (UTC) Gabor Grothendieck wrote:
The following, which was recently discussions on the rcom-l list, is a situation where coercing x1mat to a vector using as.vector results in an object that is.vector says is not a vector:
R> x1mat<-matrix(list(1,1.1,1+1i,"a",NA,NaN), 3, 2) R> is.vector(as.vector(x1mat)) [1] FALSE
If you give it a particular mode, it produces a vector:
R> as.vector(x1mat, mode = "character")
[1] "1" "1.1" "1+1i" "a" "NA" "NaN" R> as.vector(x1mat, mode = "numeric")
[1] 1.0 1.1 1.0 NA NA NaN
Warning messages: 1: imaginary parts discarded in coercion 2: out-of-range values treated as 0 in coercion to raw
A somewhat similar and simpler example is:
R> x <- data.frame(a = 1:5, b = 6:10) R> is.vector(as.vector(x)) [1] FALSE
because data.frames are also already vectors of mode "list". The man page of as.vector provides a similar example with:
R> as.vector(x, mode = "numeric") Error in as.vector(x, mode = "numeric") : (list) object cannot be coerced to double
I had discussed this with Kurt (and maybe R-devel, but I cannot find it in the archives) some time ago and the bottom line--if I recall correctly--was that is.vector() and as.vector() do not behave in the way that is.vector(as.vector(x)) always gives TRUE (or an error).
Z
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