[R] How to set up number of prin comp.

Bjørn-Helge Mevik bhx2 at mevik.net
Fri Feb 25 10:38:08 CET 2005


>         I am trying to use PrinComp to do principle component analysis. I 
> would like to know how to set the number of principle components.

I assume you mean the function princomp (case _does_ matter in R) in
package stats (which is loaded by default).  This function has no way
of specifying how many components to calculate; it always gives you
all components.  You have to select the components you want
afterwards.  See help(princomp) for details.  E.g.

X <- some matrix
pc <- princomp(X)
pc$scores[,1:4]    # The four first score vectors
pc$loadings[,1:4]  # The four first loadings

(The loadings can also be extracted with loadings(pc)[,1:4] .)

-- 
Bjørn-Helge Mevik




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