boxplot2() function
added October 11, 2012
Code File
The code for the boxplot2() function is contained in the file boxplot2.R. You can source the file directly into R by calling
source("http://www.biostat.jhsph.edu/~pmurakam/boxplot2.R")
The code is licensed under the GNU General Public License version 3, or (at your option) any later version.
Manual page
Description:
A function to produce boxplots, stratified by the values of a second factor and distinguished by different colors.
Usage:
boxplot2(y, x, by, ylab=NULL, col=NULL, ...)
Arguments:
y - a numeric vector of data values to be split into groups according to the grouping variable x (usually a factor)
x - the grouping variable (usually a factor) by which to split the numeric data y
by - the second grouping variable by which to split the numeric data y
ylab - ylab argument to boxplot()
col - vector of colors, one for each unique value of by
... - additional arguments to pass to boxplot()
See also:
boxplot, stripchart, bwplot in the lattice package
Examples:
set.seed(5678)
y = c(rnorm(20,2), rnorm(27,3), rnorm(23,0), rnorm(30,1))
x = factor(rep(c("a","b"),c(47,53)))
by = factor(rep(c("group1","group2","group1","group2"),c(20,27,23,30)))
boxplot2(y=y, x=x, by=by, ylab="y")