Back to Back Histograms

Takes two vectors or a list with x and y components, and produces back to back histograms of the two datasets.

Usage

histbackback(x, y, brks=NULL, xlab=NULL, axes=TRUE, probability=FALSE,
             xlim=NULL, ylab='', ...)

Arguments

x,y: either two vectors or a list given as x with two components. If the components have names, they will be used to label the axis (modification FEH).
brks: vector of the desired breakpoints for the histograms.
xlab: a vector of two character strings naming the two datasets.
axes: logical flag stating whether or not to label the axes.
probability: logical flag: if TRUE, then the x-axis corresponds to the units for a density. If FALSE, then the units are counts.
xlim: x-axis limits. First value must be negative, as the left histogram is placed at negative x-values. Second value must be positive, for the right histogram. To make the limits symmetric, use e.g. ylim=c(-20,20).
ylab: label for y-axis. Default is no label.
...: additional graphics parameters may be given.

Value

a list is returned invisibly with the following components:

left: the counts for the dataset plotted on the left.
right: the counts for the dataset plotted on the right.
breaks: the breakpoints used.

Side Effects

a plot is produced on the current graphics device.

Author

Pat Burns
Salomon Smith Barney
London
pburns@dorado.sbi.com

Examples

options(digits=3)
set.seed(1)
histbackback(rnorm(20), rnorm(30))



fool <- list(x=rnorm(40), y=rnorm(40))
histbackback(fool)

age <- rnorm(1000,50,10)
sex <- sample(c('female','male'),1000,TRUE)
histbackback(split(age, sex))

agef <- age[sex=='female']; agem <- age[sex=='male']
histbackback(list(Female=agef,Male=agem), probability=TRUE, xlim=c(-.06,.06))