rootogram: Trellis Displays of Tukey's Hanging Rootograms

Description

Displays hanging rootograms.

Usage

rootogram(x, ...)
## S3 method for class 'formula':
rootogram(x, data = parent.frame(),
          ylab = expression(sqrt(P(X == x))),
          prepanel = prepanel.rootogram,
          panel = panel.rootogram,
          ...)
prepanel.rootogram(x, y = table(x),
                   dfun = NULL,
                   transformation = sqrt,
                   hang = TRUE,
                   ...)
panel.rootogram(x, y = table(x),
                dfun = NULL,
                col = plot.line$col,
                lty = plot.line$lty,
                lwd = plot.line$lwd,
                alpha = plot.line$alpha,
                transformation = sqrt,
                hang = TRUE,
                ...)

Arguments

x, y

For rootogram, x is the object on which method dispatch is carried out. For the "formula" method, x is a formula describing the form of conditioning plot. The formula can be either of the f

data

For the "formula" method, a data frame containing values for any variables in the formula, as well as those in groups and subset if applicable (groups is currently ignored by the default pane

dfun

a probability mass function, to be evaluated at unique x values

prepanel, panel

panel and prepanel function used to create the display.

ylab

the y-axis label; typically a character string or an expression.

col, lty, lwd, alpha

graphical parameters

transformation

a vectorized function. Relative frequencies (observed) and theoretical probabilities (dfun) are transformed by this function before being plotted.

hang

logical, whether lines representing observed relative freuqncies should hang from the curve representing the theoretical probabilities.

...

extra arguments, passed on as appropriate. Standard lattice arguments as well as arguments to panel.rootogram can be supplied directly in the high level rootogram call.

Value

rootogram produces an object of class "trellis". The update method can be used to update components of the object and the print method (usually called by default) will plot it on an appropriate plotting device.

Details

This function implements Tukey's hanging rootograms. Also consider the rootogram function in the vcd package, especially if the number of unique values is small.

Examples

Run this code

library(lattice)

x <- rpois(1000, lambda = 50)

p <- rootogram(~x, dfun = function(x) dpois(x, lambda = 50))
p

lambdav <- c(30, 40, 50, 60, 70)

update(p[rep(1, length(lambdav))],
       aspect = "xy",
       panel = function(x, ...) {
           panel.rootogram(x,
                           dfun = function(x)
                           dpois(x, lambda = lambdav[panel.number()]))
       })


lambdav <- c(46, 48, 50, 52, 54)

update(p[rep(1, length(lambdav))],
       aspect = "xy",
       prepanel = function(x, ...) {
           tmp <-
               lapply(lambdav,
                      function(lambda) {
                          prepanel.rootogram(x,
                                             dfun = function(x)
                                             dpois(x, lambda = lambda))
                      })
           list(xlim = range(sapply(tmp, "[[", "xlim")),
                ylim = range(sapply(tmp, "[[", "ylim")),
                dx = do.call("c", lapply(tmp, "[[", "dx")),
                dy = do.call("c", lapply(tmp, "[[", "dy")))
       },
       panel = function(x, ...) {
           panel.rootogram(x,
                           dfun = function(x)
                           dpois(x, lambda = lambdav[panel.number()]))
           grid::grid.text(bquote(Poisson(lambda == .(foo)),
                                  where = list(foo = lambdav[panel.number()])),
                           y = 0.15,
                           gp = grid::gpar(cex = 1.5))
       },
       xlab = "",
       sub = "Random sample from Poisson(50)")