Rotate histogram in R or overlay a density in a barplot

Question

I would like to rotate a histogram in R, plotted by hist(). The question is not new, and in several forums I have found that it is not possible. However, all these answers date

Answer 1

Thank you, Tim and Paul. You made me think harder and use what hist() actually provides.

This is my solution now (with great help from Alex Pl.):

scatterBar.Norm <- function(x,y) {
 zones <- matrix(c(2,0,1,3), ncol=2, byrow=TRUE)
 layout(zones, widths=c(5/7,2/7), heights=c(2/7,5/7))
 xrange <- range(x)
 yrange <- range(y)
 par(mar=c(3,3,1,1))
 plot(x, y, xlim=xrange, ylim=yrange, xlab="", ylab="", cex=0.5)
 xhist <- hist(x, plot=FALSE, breaks=seq(from=min(x), to=max(x), length.out=20))
 yhist <- hist(y, plot=FALSE, breaks=seq(from=min(y), to=max(y), length.out=20))
 top <- max(c(xhist$density, yhist$density))
 par(mar=c(0,3,1,1))
 barplot(xhist$density, axes=FALSE, ylim=c(0, top), space=0)
 x.xfit <- seq(min(x),max(x),length.out=40)
 x.yfit <- dnorm(x.xfit, mean=mean(x), sd=sd(x))
 x.xscalefactor <- x.xfit / seq(from=0, to=19, length.out=40)
 lines(x.xfit/x.xscalefactor, x.yfit, col="red")
 par(mar=c(3,0,1,1))
 barplot(yhist$density, axes=FALSE, xlim=c(0, top), space=0, horiz=TRUE)
 y.xfit <- seq(min(y),max(y),length.out=40)
 y.yfit <- dnorm(y.xfit, mean=mean(y), sd=sd(y))
 y.xscalefactor <- y.xfit / seq(from=0, to=19, length.out=40)
 lines(y.yfit, y.xfit/y.xscalefactor, col="red")
}

For examples:

require(MASS)
#Sigma <- matrix(c(2.25, 0.8, 0.8, 1), 2, 2)
Sigma <- matrix(c(1, 0.8, 0.8, 1), 2, 2)
mvnorm <- mvrnorm(1000, c(0,0), Sigma) ; scatterBar.Norm(mvnorm[,1], mvnorm[,2])

An asymmetric Sigma leads to a somewhat bulkier histogram of the respective axis.

The code is left deliberately "unelegant" in order to increase comprehensibility (for myself when I revisit it later...).

Niels