[R] NAs introduced by coercion in dist()
P.Dalgaard at biostat.ku.dk
Wed May 2 16:17:03 CEST 2007
> I work with Windows and use R version 2.4.1. I am JUST starting to learn this
> I get this warning message 'NAs introduced by coercion' while trying to
> build a distance matrix (to be analyzed with NMDS later) from a 336 x 100
> data matrix. The original matrix has lots of zeros and no missing values,
> but I don't think this should matter.
> I searched this forum and people have suggested that the warning should be
> ignored but when I try to print the distance matrix I only get the row
> numbers (the matrix seems to be 'empty') and I'm not being able to judge
> whether the matrix worked or not.
> To get the distance matrix I wrote:
> dist.PxMx <- dist (PeaksMatrix, method='euclidean', diag=FALSE, upper=FALSE)
> I tried including the p argument (included in the help for dist()) and
> leaving it out, but that didn't seem to change anything. I think that's
> required for one distance measure though, not for euclidean dist.
> Should I really ignore this warning? If so, why am I not being able to see
> the distance matrix?
That error message is often generated by things like
NAs introduced by coercion
so the immediate suspicion is that your data are not what you think they
The output of str(PeaksMatrix) should be illuminating.
O__ ---- Peter Dalgaard Øster Farimagsgade 5, Entr.B
c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K
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~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk) FAX: (+45) 35327907
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