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. doi:10.2307/2334381.
Gabriel, K. R. and Odoroff, C. L. (1990). Biplots in biomedical research. Statistics in Medicine, 9, 469–485. doi:10.1002/sim.4780090502.
require(graphics)
biplot(princomp(USArrests))