Name Plot: Names or Numbers instead of Points in Plot

A utility function which basically calls plot(*, type="n") and text. To have names or numbers instead of points in a plot is useful for identifaction, e.g., in a residual plot, see also TA.plot.

Usage

n.plot(x, y = NULL, nam = NULL, abbr = n >= 20 || max(nchar(nam))>=8,
       type = "n", xlab = NULL, ylab = NULL, log = "",
       cex = par("cex"), col = par("col"), pt.col = par("col"), ...)

Arguments

x, y: coordinates at which to plot. If y is missing, x is used for both, if it's a data.frame, list, 2-column matrix etc – via xy.coords; formula do not work.
nam: the labels to plot at each (x,y). Per default, these taken from the data x and y; case numbers 1:n are taken if no names are available.
abbr: logical indicating if the nam labels should be abbreviated – with a sensible default.
type: passed to plot.default,a string denoting the type of the initial plot() call; the default draws nothing but the axes, etc; type = "l" maybe useful occasionally.
xlab, ylab: labels for the x- and y- axis, the latter being empty by default.
log: character specifying if log scaled axes should be used, see plot.default.
cex: plotting character expansion, see par.
col: color to use for text().
pt.col: color to use for plot() if type is set different to "n".
...: further arguments to be passed to the plot call.

Value

invisibly, a character vector with the labels used.

Author

Martin Maechler, since 1992

Examples

 n.plot(1:20, cumsum(rnorm(20)))

 data(cars)
 with(cars, n.plot(speed, dist, cex = 0.8, col = "forest green"))


## visualize periodicity of  exp(<complex>)   {pass args to plot.default() via `...`}
cpxN <- function(r,i) setNames(complex(real=r, imaginary=i), i)
n.plot(exp(cpxN(2, 0:32)), type = "l", pt.col = "gray", asp = 1,
       col = adjustcolor(rainbow(33), offset = rep(-1/4, 4)),
       panel.first = abline(h=0, v=0, lty=3, col="gray30"))
symbols(0,0, circles = exp(2), inches=FALSE, fg = adjustcolor(2, 1/3), lwd=3, add=TRUE)