BCA (version 0.9-3)

bpCent: Two Dimensional Biplot of a Clustering Solution

Description

Plot a biplot of a clustering solution on the current graphics device.

Usage

bpCent(pc, clsAsgn, data.pts = TRUE, centroids = TRUE,  choices = 1:2, scale = 1, pc.biplot=FALSE, 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

pc

The prcomp object of the data used in clustering.

clsAsgn

A vector containing the cluster assignment for each record in the clustering data.

data.pts

If TRUE the point for each record is plotted.

centroids

If TRUE the centroid for each cluster is plotted.

choices

length 2 vector specifying the components to plot.

scale

The variables scaled by lambda ^ scale and the observations are scaled by lambda ^ (1-scale), where lambda are the eigen values of the principal components solution. scale should be between 0 and 1.

pc.biplot

If true, then lambda = 1 and the observations are are scaled up the sqrt(n) and the variables scaled down by sqrt(n). In this case the inner product between variables approximate covariances, and the distances between observations approximate Mahalanobis distance. Gabriel refers to this as a "principal component biplot".

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 paletter 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, or 1:n is the dimname is NULL.

ylabs

A vector of character strings to label the second set of points: the default is to use the row dimname of y, or 1:n is the dimname is NULL.

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 by arrow.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.

Side Effects

a plot is produced on the current graphics device.

Details

This function is a reworking of biplot in order to allow the cluster centroids of a clustering solution to be displayed as well as the individual data points. If both data.pts and centroids are set to FALSE then only the variable directional vectors are displayed.

Graphical parameters can also be given to biplot.

See Also

biplot