p.tachoPlot function

Draw Symbol on a Plot

Puts a symbol (pointer) on a plot at each of the specified locations.

p.tachoPlot(x, y, z, angle=c(pi/4,3*pi/4), size,
            method = c("robust", "sensitive", "rank"),
            legend = TRUE, show.method = legend,
            xlab = deparse(substitute(x)), ylab = deparse(substitute(y)),
            xlim, ylim, ...)

Arguments

• x,y,z: coordinates of points. Numeric vectors of the same length. Missing values (NAs) are allowed.

• angle: numeric vector whose elements give the angles between the horizontal baseline and the minimum and maximum direction of the pointer measured clockwise in radians.

• size: length of the pointers in cm.

• method: string specifying the method to calculate the angle of the pointer. One of "sensitive", "robust" or "rank". Only the first two characters are necessary.

  The minimum and maximum direction of the pointer corresponds to min(z) and max(z) if method is "sensitive" or "rank"

  and to the upper and lower extreme of z if method is "robust"

  (see boxplot or rrange for details). The angle is proportional to z or rank(z) in case of method="rank".

• legend: logical flag: if TRUE (default), a legend giving the values of the minimum and maximum direction of the pointer is drawn.

• show.method: logical flag, defaulting to legend; if true, the method name is printed.

• xlab,ylab: labels for x and y axis; defaults to the expression used in the function call.

• xlim,ylim: numeric of length 2, the limits for the x and y axis, respectively; see plot.default.

• ...: further arguments to plot. Graphical parameters (see par) may also be supplied as arguments to this function.

Side Effects

A plot is created on the current graphics device.

Details

A scatter plot of the variables x and y is plotted. The value of the third variable z is given by the direction of a pointer (similar to a tachometer). Observations whose z-coordinate is missing are marked by a dot.

Author(s)

Christian Keller, June 1995

See Also

symbols

Examples

data(state)
data(USArrests)
p.tachoPlot(state.center $x, state.center $y, USArrests[,"UrbanPop"])

data(mtcars)
par(mfrow=c(2,2))
## see the difference between the three methods (not much differ. here!)

p.tachoPlot(mtcars$hp, mtcars$disp, mtcars$mpg, method="sens")
p.tachoPlot(mtcars$hp, mtcars$disp, mtcars$mpg, method="rank")
p.tachoPlot(mtcars$hp, mtcars$disp, mtcars$mpg, method="rob")