AFM Compositions of Aphyric Skye Lavas
Arguments
A
|
Percentage of sodium and potassium oxides
|
F
|
Percentage of iron oxide
|
M
|
Percentage of magnesium oxide
|
SUMMARY
The Skye
data frame has 23 rows and 3 columns.DATA DESCRIPTION
This data frame contains the following columns:SOURCE
J. Aitchison (1986)
The Statistical Analysis of Compositional Data.
Chapman and Hall, p.360.
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.Examples
# ternary() is from the on-line answers.
ternary <- function(X, pch = par("pch"), lcex = 1,
add = F, ord = 1:3, ...)
{
X <- as.matrix(X)
if(any(X) < 0) stop("X must be non-negative")
s <- drop(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=F,
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], ...)
}
data(Skye)
ternary(as.matrix(Skye)/100, ord=c(1,3,2))