lboxplot function - boxplots lists of lists

lboxplot.R

lboxplot <- function(x, cols=2:(length(x)+1), ...) {
    xl <- length(x)
    if (xl<2) stop("Length of x must be >=2")
    xn <- sapply(x, length)
    if (!all(xn==xn[1])) stop ("Element lengths of x must all be the same")
    xnames <- sapply(x, names)
    if (!all(apply(xnames, 1, function(y) all(y==y[1])))) stop("Each element of x must have matching names")
    xn <- xn[1]
    xu <- unlist(x, recursive=FALSE)[rep(1:xn, each=xl)+rep((1:xl-1)*xn, xn)]
    boxplot(xu, col=cols, xaxt="n", ...)
    axis(1, seq(1+(xl-1)/2, length(xu)-(xl-1)/2, length.out=xn), names(x[[1]]), las=2)
    abline(v=1:(xn-1)*xl+0.5, lty=2, col="red")
}