plotStep: Plot a Step Function

In sfsmisc: Utilities from 'Seminar fuer Statistik' ETH Zurich

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 à droite, limite à 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.

Side Effects

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

Author(s)

Martin Maechler, Seminar for Statistics, ETH Zurich, [e-mail], 1991 ff.

See Also

The plot methods plot.ecdf and plot.stepfun in R which 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

sfsmisc documentation built on Sept. 11, 2024, 6:53 p.m.