[R] princomp with more coloumns than rows: why not?
Bjørn-Helge Mevik
bhx2 at mevik.net
Thu Oct 16 11:14:13 CEST 2003
As of R 1.7.0, princomp no longer accept matrices with more coloumns
than rows. I'm curious: Why was this decision made?
I work a lot with data where more coloumns than rows is more of a rule
than an exception (for instance spectroscopic data). To me, princomp
have two advantages above prcomp: 1) It has a predict method, and 2)
it has a biplot method.
A biplot method shouldn't be too difficult to implement (I believe
I've seen one on R-help).
A predict method seems to be more difficult, because the prcomp object
doesn't include the means that need to be subtracted from the new
data. Would it break conformance with S to let prcomp return the
means as well?
--
Sincerely,
Bjørn-Helge Mevik
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