[R] Getting the eigenvectors for the dependent variables from principal components analysis

From: Josh B <joshb41_at_yahoo.com>
Date: Tue, 15 Jun 2010 15:02:11 -0700 (PDT)


Dear listserv,

I am trying to perform a principal components analysis and create an output table of the eigenvalues for the dependent variables. What I want is to see which variables are driving each principal components axis, so I can make statements like, "PC1 mostly refers to seed size" or something like that.

For instance, if I try the example from ?prcomp

> prcomp(USArrests, scale = TRUE)

Now what? None of the components of prcomp-class objects appear to have this information. "rotation" will give me the eigenvectors for the individual data points, NOT the eigenvectors for the dependent variables for each PC axis.

Alternatively, I could try the example from ?princomp

> princomp(USArrests, cor = TRUE)

But I have the same problem -- now what? None of the components of princomp-class objects appear to have the information I'm after.

Thanks very much in advance for any help!



Josh Banta, Ph.D
Center for Genomics and Systems Biology
New York University
100 Washington Square East
New York, NY 10003
Tel: (212) 998-8465
http://plantevolutionaryecology.org
      
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