flexclust (version 0.8-1)

projAxes: Add Arrows for Projeted Axes to a Plot

Description

Adds arrows for original coordinate axes to a projection plot. Currently only a method for the results of prcomp exists.

Usage

projAxes(object, which=1:2, center=NULL,
                     col="red", radius=NULL,
                     minradius=0.1, textargs=list(col=col),
                     col.names=getColnames(object),
                     which.names="", ...)
placeLabels(object)
## S3 method for class 'projAxes':
placeLabels(object)

Arguments

object

Return value of a projection method like prcomp.

which

Index number of dimensions of (projected) input space that have been plotted.

center

Center of the coordinate system to use in projected space. Default is the center of the plotting region.

col

Color of arrows.

radius

Relative size of the arrows.

minradius

Minimum radius of arrows to include (relative to arrow size).

textargs

List of arguments for text.

col.names

Variable names of the original data.

which.names

A regular expression which variable names to include in the plot.

...

Passed to arrows.

Value

• projAxes returns an object of class "projAxes", which is added to the current plot by its show and plot method.

Examples

data(milk)
milk.pca <- prcomp(milk, scale=TRUE)

## create a biplot step by step
plot(predict(milk.pca), type="n")
text(predict(milk.pca), rownames(milk), col="green", cex=0.8)
projAxes(milk.pca)

## the same, but arrows are blue, centered at origin and all arrows are
## plotted 
plot(predict(milk.pca), type="n")
text(predict(milk.pca), rownames(milk), col="green", cex=0.8)
projAxes(milk.pca, col="blue", center=0, minradius=0)

## use points instead of text, plot PC2 and PC3, manual radius
## specification, store result
plot(predict(milk.pca)[,c(2,3)])
arr <- projAxes(milk.pca, which=c(2,3), radius=1.2)
plot(arr)