Hi,

 

I am using "biplot" (in package "stats") to visualize the results of some
PCA analyses.  When I use scale=0 in the biplot function, it draws X (PC1)
and Y (PC2) axes, with the scales multiplied by sqrt(N), where N is the
sample size.  Is there a way to change these scales so that the actual
values of PC1 and PC2 are shown, instead of multiplication by sqrt(n)?   

 

Also, how can I plot the points in biplot with different colors or symbols
corresponding to a grouping variable, instead of sample row number?

 

Thanks for any suggestions.

 

Best,

Ravi.

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Ravi Varadhan, Ph.D.

Assistant Professor, The Center on Aging and Health

Division of Geriatric Medicine and Gerontology 

Johns Hopkins University

Ph: (410) 502-2619

Fax: (410) 614-9625

Email: rvaradhan@jhmi.edu

Webpage:  http://www.jhsph.edu/agingandhealth/People/Faculty/Varadhan.html

 

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