AFM Compositions of Aphyric Skye Lavas
The Skye data frame has 23 rows and 3 columns.
Skye
This data frame contains the following columns:
APercentage of sodium and potassium oxides.
FPercentage of iron oxide.
MPercentage of magnesium oxide.
R. N. Thompson, J. Esson and A. C. Duncan (1972) Major element chemical variation in the Eocene lavas of the Isle of Skye. J. Petrology, 13, 219–253.
J. Aitchison (1986) The Statistical Analysis of Compositional Data. Chapman and Hall, p.360.
Venables, W. N. and Ripley, B. D. (2002) Modern Applied Statistics with S. Fourth edition. Springer.
# ternary() is from the on-line answers.
ternary <- function(X, pch = par("pch"), lcex = 1,
add = FALSE, ord = 1:3, ...)
{
X <- as.matrix(X)
if(any(X < 0)) stop("X must be non-negative")
s <- drop(X %*% rep(1, ncol(X)))
if(any(s<=0)) stop("each row of X must have a positive sum")
if(max(abs(s-1)) > 1e-6) {
warning("row(s) of X will be rescaled")
X <- X / s
}
X <- X[, ord]
s3 <- sqrt(1/3)
if(!add)
{
oldpty <- par("pty")
on.exit(par(pty=oldpty))
par(pty="s")
plot(c(-s3, s3), c(0.5-s3, 0.5+s3), type="n", axes=FALSE,
xlab="", ylab="")
polygon(c(0, -s3, s3), c(1, 0, 0), density=0)
lab <- NULL
if(!is.null(dn <- dimnames(X))) lab <- dn[[2]]
if(length(lab) < 3) lab <- as.character(1:3)
eps <- 0.05 * lcex
text(c(0, s3+eps*0.7, -s3-eps*0.7),
c(1+eps, -0.1*eps, -0.1*eps), lab, cex=lcex)
}
points((X[,2] - X[,3])*s3, X[,1], ...)
}
ternary(Skye/100, ord=c(1,3,2))Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.