A
| Percentage of sodium and potassium oxides |
F
| Percentage of iron oxide |
M
| Percentage of magnesium oxide |
Skye
data frame has 23 rows and 3 columns.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.
# 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], ...) } data(Skye) ternary(Skye/100, ord=c(1,3,2))