sfsmisc (version 0.95-8)

plotStep: Plot a Step Function

Description

Plots a step function f(x)= $\sum_i y_i 1_[ t_{i-1}, t_i ](x)$, i.e., a piecewise constant function of one variable. With one argument, plots the empirical cumulative distribution function.

Usage

plotStep(ti, y,
          cad.lag = TRUE,
          verticals = !cad.lag,
          left.points= cad.lag, right.points= FALSE, end.points= FALSE,
	  add = FALSE,
	  pch = par('pch'),
          xlab=deparse(substitute(ti)), ylab=deparse(substitute(y)),
          main=NULL, ...)

Arguments

ti

numeric vector = X[1:N] or t[0:n].

y

numeric vector y[1:n]; if omitted take y = k/N for empirical CDF.

cad.lag

logical: Draw 'cad.lag', i.e., continue � droite, limite � gauche. Default = TRUE.

verticals

logical: Draw vertical lines? Default= ! cad.lag

left.points

logical: Draw left points? Default= cad.lag

right.points

logical: Draw right points? Default= FALSE

end.points

logical: Draw 2 end points? Default= FALSE

add

logical: Add to existing plot? Default= FALSE

pch

plotting character for points, see par().

xlab,ylab

labels of x- and y-axis

main

main title; defaults to the call' if you do not want a title, use main = "".

...

Any valid argument to plot(..).

Value

• invisibly: List with components t and y.

encoding

latin1

Side Effects

Calls plot(..), points(..), segments(..) appropriately and plots on current graphics device.

See Also

The plot methods plot.ecdf and plot.stepfun in Rwhich are conceptually nicer.

segments(..., method = "constant").

Examples

##-- Draw an Empirical CDF  (and see the default title ..)
plotStep(rnorm(15))

plotStep(runif(25), cad.lag=FALSE)
plotStep(runif(25), cad.lag=FALSE, add=TRUE, lty = 2)

ui <- sort(runif(20))
plotStep(ui, ni <- cumsum(rpois(19, lambda=1.5) - 1.5), cad.lag = FALSE)
plotStep(ui, ni, verticals = TRUE, right.points = TRUE)

plotStep(rnorm(201), pch = '.') #- smaller points