biplot
Biplot of Multivariate Data
Plot a biplot on the current graphics device.
- Keywords
- multivariate, hplot
Usage
biplot(x, ...)
"biplot"(x, y, var.axes = TRUE, col, cex = rep(par("cex"), 2), xlabs = NULL, ylabs = NULL, expand = 1, xlim = NULL, ylim = NULL, arrow.len = 0.1, main = NULL, sub = NULL, xlab = NULL, ylab = NULL, ...)
Arguments
- x
- The
biplot
, a fitted object. Forbiplot.default
, the first set of points (a two-column matrix), usually associated with observations. - y
- The second set of points (a two-column matrix), usually associated with variables.
- var.axes
- If
TRUE
the second set of points have arrows representing them as (unscaled) axes. - col
- A vector of length 2 giving the colours for the first and
second set of points respectively (and the corresponding axes). If a
single colour is specified it will be used for both sets. If
missing the default colour is looked for in the
palette
: if there it and the next colour as used, otherwise the first two colours of the palette are used. - cex
- The character expansion factor used for labelling the points. The labels can be of different sizes for the two sets by supplying a vector of length two.
- xlabs
- A vector of character strings to label the first set of
points: the default is to use the row dimname of
x
, or1:n
if the dimname isNULL
. - ylabs
- A vector of character strings to label the second set of
points: the default is to use the row dimname of
y
, or1:n
if the dimname isNULL
. - expand
- An expansion factor to apply when plotting the second set of points relative to the first. This can be used to tweak the scaling of the two sets to a physically comparable scale.
- arrow.len
- The length of the arrow heads on the axes plotted in
var.axes
is true. The arrow head can be suppressed byarrow.len = 0
. - xlim, ylim
- Limits for the x and y axes in the units of the first set of variables.
- main, sub, xlab, ylab, ...
- graphical parameters.
Details
A biplot is plot which aims to represent both the observations and
variables of a matrix of multivariate data on the same plot. There are
many variations on biplots (see the references) and perhaps the most
widely used one is implemented by biplot.princomp
.
The function biplot.default
merely provides the
underlying code to plot two sets of variables on the same figure.
Graphical parameters can also be given to biplot
: the size of
xlabs
and ylabs
is controlled by cex
.
Side Effects
a plot is produced on the current graphics device.
References
K. R. Gabriel (1971). The biplot graphical display of matrices with application to principal component analysis. Biometrika 58, 453--467.
J.C. Gower and D. J. Hand (1996). Biplots. Chapman & Hall.
See Also
biplot.princomp
, also for examples.