R: Draw a Label on an Ellipse-like Object

label.ellipse {heplots}

R Documentation

Draw a Label on an Ellipse-like Object

Description

Draws a label on an ellipse (or similar closed ploygon object) allowing a label.pos argument to specify the position of the label as center, bottom, left, top, or right relative to the object.

Usage

label.ellipse(ellipse, label, col = "black", label.pos = NULL, 
      xpd = TRUE, tweak = 0.5 * c(strwidth("M"), strheight("M")), ...)

Arguments

`ellipse`	A two-column matrix, or an object that can be coerced to one.
`label`	Label text, a character string, or expression (or coercible to such a type).
`col`	Label color
`label.pos`	Label position, an integer (in `0:4`) or character string (in `c("center", "bottom", "left", "top", "right")`). Values of 1, 2, 3 and 4, respectively indicate positions below, to the left of, above and to the right of the max/min coordinates of the ellipse; the value 0 specifies the centroid of the `ellipse` object. The default, `label.pos=NULL` uses the correlation of the `ellipse` to determine "top" (r>=0) or "bottom" (r<0).
`xpd`	logical. Whether to allow the label to go beyond the plot area.
`tweak`	A two element vector specifying minor adjustments applied to the x or y coordinate of the label, depending on `label.pos`. The defaults are one-half the width and height of an uppercase "M" on the current graphics device. Alternatively, you can set `tweak=c(0,0)` and use `offset` to achieve more general adjustments.
`...`	Other arguments passed to `text`, such as `offset`, `srt`, `font`, `family`, etc.

Details

Like text, this function simply adds to an existing base graphics plot.

Value

None.

Author(s)

Michael Friendly

Examples

op <- par(mfrow=c(1,2))
plot(c(-2,2), c(-3,3), type="n", xlab="x", ylab="y")
E <- ellipse(c(0,0), matrix(c(1,2,2,5), 2, 2), 1, add=TRUE)

label.ellipse(E, "default", col="red", cex=2)
label.ellipse(E, "center", label.pos=0)
label.ellipse(E, "bottom", label.pos=1)
label.ellipse(E, "top", label.pos=3)
label.ellipse(E, "left", label.pos=2)
label.ellipse(E, "right", label.pos=4)

plot(c(-2,2), c(-3,3), type="n", xlab="x", ylab="y")
E <- ellipse(c(0,0), matrix(c(1,-2,-2,5), 2, 2), 1, add=TRUE)

label.ellipse(E, "default", col="red", cex=2)
label.ellipse(E, "center", label.pos="center")
label.ellipse(E, "bottom", label.pos=1, cex=1.5)
label.ellipse(E, "top", label.pos=3, cex=1.5)
label.ellipse(E, "left", label.pos=2, cex=1.5)
label.ellipse(E, "right", label.pos=4, cex=1.5)
par(op)

[Package heplots version 1.0-15 Index]