[R] How to scale arrows to approximately fill a plot region?

[Mark Difford]

On Dec 07, 2011 at 10:20pm Michael Friendly asked:

> How to scale arrows to approximately fill a plot region?

Michael,

Following Uwe...If you want code that does it then look at what Daniel
Chessel did in package ade4:

##
> scatter.dudi
function (x, xax = 1, yax = 2, clab.row = 0.75, clab.col = 1, 
    permute = FALSE, posieig = "top", sub = NULL, ...) 
{
    if (!inherits(x, "dudi")) 
        stop("Object of class 'dudi' expected")
    opar <- par(mar = par("mar"))
    on.exit(par(opar))
    coolig <- x$li[, c(xax, yax)]
    coocol <- x$c1[, c(xax, yax)]
    if (permute) {
        coolig <- x$co[, c(xax, yax)]
        coocol <- x$l1[, c(xax, yax)]
    }
    s.label(coolig, clab = clab.row)
    born <- par("usr")
    k1 <- min(coocol[, 1])/born[1]
    k2 <- max(coocol[, 1])/born[2]
    k3 <- min(coocol[, 2])/born[3]
    k4 <- max(coocol[, 2])/born[4]
    k <- c(k1, k2, k3, k4)
    coocol <- 0.9 * coocol/max(k)
    s.arrow(coocol, clab = clab.col, add.p = TRUE, sub = sub, 
        possub = "bottomright")
    add.scatter.eig(x$eig, x$nf, xax, yax, posi = posieig, ratio = 1/4)
}
<environment: namespace:ade4>

Regards, Mark.

-----
Mark Difford (Ph.D.)
Research Associate
Botany Department
Nelson Mandela Metropolitan University
Port Elizabeth, South Africa
--
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