# Skye

0th

Percentile

##### AFM Compositions of Aphyric Skye Lavas

The Skye data frame has 23 rows and 3 columns.

Keywords
datasets
Skye
##### Format

This data frame contains the following columns:

A

Percentage of sodium and potassium oxides.

F

Percentage of iron oxide.

M

Percentage of magnesium oxide.

##### References

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.

• Skye
##### Examples
# NOT RUN {
# ternary() is from the on-line answers.
ternary <- function(X, pch = par("pch"), lcex = 1,
add = FALSE, ord = 1:3,
# }
# NOT RUN {
…
# }
# NOT RUN {
)
{
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)
{
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],
# }
# NOT RUN {
…
# }
# NOT RUN {
)
}

ternary(Skye/100, ord=c(1,3,2))
# }
Documentation reproduced from package MASS, version 7.3-51.1, License: GPL-2 | GPL-3

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