# S3 method for prcomp biplot(x, choices = 1:2, scale = 1, pc.biplot = FALSE, …)
# S3 method for princomp biplot(x, choices = 1:2, scale = 1, pc.biplot = FALSE, …)
an object of class
length 2 vector specifying the components to plot. Only the default is a biplot in the strict sense.
The variables are scaled by
lambda ^ scale and the
observations are scaled by
lambda ^ (1-scale) where
lambda are the singular values as computed by
0 <= scale <= 1, and a warning
will be issued if the specified
scale is outside this range.
If true, use what Gabriel (1971) refers to as a "principal component
lambda = 1 and observations scaled up by sqrt(n) and
variables scaled down by sqrt(n). Then inner products between
variables approximate covariances and distances between observations
approximate Mahalanobis distance.
optional arguments to be passed to
a plot is produced on the current graphics device.
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
pc.biplot = TRUE.
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.