Augment a Dendrogram with Tiles

DESCRIPTION:
Plots vertical barplots of the var argument under each leaf of the dendogram. The screen should be divided by tree.screens or split.screen.

USAGE:
tile.tree(tree, var, screen.arg = ascr + 1, axes = T)

REQUIRED ARGUMENTS:
tree:
fitted model object of class tree. This is assumed to be the result of some function that produces an object with the same named components as that returned by the tree function.
var:
factor to be tiled; if var is numeric, it is first quantized into four equi-sized ordered levels. This must have length agreeing with the data used to grow tree.

OPTIONAL ARGUMENTS:
screen.arg:
integer denoting the screen to be used for the plotting. By default the active current screen plus 1 (the next one) is used. See split.screen and tree.screens for more details.
axes:
logical flag: if TRUE (the default), a vertical axis is drawn at the right edge of the barplots.

VALUE:
invisibly returns the matrix of frequency counts for the observations in each leaf.

SIDE EFFECTS:
vertical barplots of var lined up under each leaf of the dendrogram. The width of each tile shows the count in that level for observations at that node. Assumes that tree.screens has been used to divide the graphics window.

SEE ALSO:
tree .

EXAMPLES:
z.auto <- tree(Mileage ~ Weight, car.test.frame)
tree.screens()
plot(z.auto)
tile.tree(z.auto, HP)