biplot.princomp {stats}  R Documentation 
Produces a biplot (in the strict sense) from the output of
princomp
or prcomp
## S3 method for class 'prcomp' biplot(x, choices = 1:2, scale = 1, pc.biplot = FALSE, ...) ## S3 method for class 'princomp' biplot(x, choices = 1:2, scale = 1, pc.biplot = FALSE, ...)
x 
an object of class 
choices 
length 2 vector specifying the components to plot. Only the default is a biplot in the strict sense. 
scale 
The variables are scaled by 
pc.biplot 
If true, use what Gabriel (1971) refers to as a "principal component
biplot", with 
... 
optional arguments to be passed to

This is a method for the generic function biplot
. There is
considerable confusion over the precise definitions: those of the
original paper, Gabriel (1971), are followed here. Gabriel and
Odoroff (1990) use the same definitions, but their plots actually
correspond to pc.biplot = TRUE
.
a plot is produced on the current graphics device.
Gabriel, K. R. (1971). The biplot graphical display of matrices with applications to principal component analysis. Biometrika, 58, 453–467.
Gabriel, K. R. and Odoroff, C. L. (1990). Biplots in biomedical research. Statistics in Medicine, 9, 469–485.
require(graphics) biplot(princomp(USArrests))