How to plot a fan (Polar) Dendrogram in R?

Question

I'm referring to something like this:

suggested dataset for showing a solutions:

data(mtcars)
plot(hclust(dist(mtcars)))

Answer 1

In phylogenetics, this is a fan phylogram, so you can convert this to phylo and use ape:

library(ape)
library(cluster) 
data(mtcars)
plot(as.phylo(hclust(dist(mtcars))),type="fan")

Result:

Answer 2

Did you see this post? http://groups.google.com/group/ggplot2/browse_thread/thread/8e1efd0e7793c1bb

Take the example, add coord_polar() and reverse the axes and you get pretty close:

library(cluster) 
data(mtcars)
x <- as.phylo(hclust(dist(mtcars)))

p <- ggplot(data=x)
p <- p + geom_segment(aes(y=x,x=y,yend=xend,xend=yend), colour="blue",alpha=1) 
p <- p + geom_text(data=label.phylo(x), aes(x=y, y=x, label=label),family=3, size=3) + xlim(0, xlim) + coord_polar()

theme <- theme_update(  axis.text.x = theme_blank(),
                        axis.ticks = theme_blank(),
                        axis.title.x = theme_blank(),
                        axis.title.y = theme_blank(),
                        legend.position = "none"
                     )
p <- p + theme_set(theme)
print(p)