Produces a plot in which both the observations and the variables
are represented in a two dimensional space.
This function is an S Version 3 generic (see Methods);
method functions can be written to handle specific
S Version 3 classes of data. Classes which already
have methods for this function include:
princomp
,
factanal.
a logical vector giving the variables for which arrows should be drawn.
This may have names, which are (partially) matched against the names
of the variables, or without names it is replicated to have length
equal to the number of variables.
col
vector of length 1 or 2 stating which colors to use for the observations
and for the variables.
The default is
par("col") for the observations and
par("col")+1 for
the variables.
cex
vector of length 1 or 2 giving the
cex parameter for the observations
and for the variables.
The default is to use the current
cex for both.
olab
vector of character strings which label the observations.
This will be replicated to be the proper length.
The default is to use the dimnames from
obs if present, and the
observation number otherwise.
vlab
vector of character strings which label the variables; this must have
length equal to the number of variables.
This may also be a logical vector giving which variables to label.
The default is to use the appropriate dimnames from
bivars.
expand
a number giving the factor by which to expand or contract the computed scale
for the variables.
xlim
the limits for the x-axis on the scale of the observations.
ylim
the limits for the y-axis on the scale of the observations.
Graphical parameters may also be supplied as arguments to
this function (see
).
SIDE EFFECTS:
a plot is created on the current graphics device.
REFERENCES:
Gabriel, K. R. (1971).
The biplot graphical display of matrices with applications to principal
component analysis.
Biometrika58 453-467.
Gabriel, K. R. and Odoroff, C. L. (1990).
Biplots in biomedical research.
Statistics in Medicine.9 469-485.
Seber, G. A. F. (1984).
Multivariate Observations.
Wiley; New York.