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
maybe, the point is that is.vector "attempts to coerce its argument into a vector", but here it fails is.matrix(as.vector(x1mat)) [1] TRUE Matthias> > 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 > > ______________________________________________ > R-devel@stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel
I would have thought it would be an error to attempt and fail. Actually, to make it a vector all that has to be done is to zap the dim attribute: dim(x1mat) <- NULL # now its a vector It seems to know how to do that in the case of an atomic matrix, just not a non-atomic one. Here it is for an atomic matrix where it does return TRUE: is.vector(as.vector(matrix(1:12,4))) # TRUE <Matthias.Kohl <at> uni-bayreuth.de> writes: : : maybe, the point is that is.vector "attempts to coerce its argument into a : vector", but here it fails : : is.matrix(as.vector(x1mat)) : [1] TRUE : : Matthias : : > : > 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 : > : > ______________________________________________ : > R-devel <at> stat.math.ethz.ch mailing list : > https://stat.ethz.ch/mailman/listinfo/r-devel : : ______________________________________________ : R-devel <at> stat.math.ethz.ch mailing list : https://stat.ethz.ch/mailman/listinfo/r-devel : :
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] FALSEIf 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