Quantile-Quantile plots for comparing two Distributions
qq(x, data, …)
# S3 method for formula qq(x, data, aspect = "fill", panel = lattice.getOption("panel.qq"), prepanel, scales, strip, groups, xlab, xlim, ylab, ylim, f.value = NULL, drop.unused.levels = lattice.getOption("drop.unused.levels"), …, lattice.options = NULL, qtype = 7, default.scales = list(), default.prepanel = lattice.getOption("prepanel.default.qq"), subscripts, subset)
The object on which method dispatch is carried out.
x should be a formula of the
y ~ x | g1 * g2 * …, where
x should be a
numeric variable, and
y a factor, shingle, character, or
numeric variable, with the restriction that there must be exactly
two levels of
y, which divide the values of
x into two
groups. Quantiles for these groups will be plotted against each
other along the two axes.
formula method, an optional data source (usually a
data frame) in which variables are to be evaluated (see
xyplot for details).
An optional numeric vector of probabilities, quantiles corresponding
to which should be plotted. This can also be a function of a single
integer (representing sample size) that returns such a numeric
vector. A typical value for this argument is the function
ppoints, which is also the S-PLUS default. If specified, the
probabilities generated by this function is used for the plotted
quantiles, through the
f.value defaults to
NULL, which is equivalent to
f.value = function(n) ppoints(n, a = 1)
This has the effect of including the minimum and maximum data values
in the computed quantiles. This is similar to what happens for
qqplot but different from the default behaviour of
x, this argument can be used to restrict the number
of quantiles plotted.
A function, called once for each panel, that uses the packet (subset
of panel variables) corresponding to the panel to create a display.
The default panel function
panel.qq is documented
separately, and has arguments that can be used to customize its
output in various ways. Such arguments can usually be directly
supplied to the high-level function.
type argument for
Fallback prepanel function. See
Further arguments. See corresponding entry in
for non-trivial details.
f.value for specifics.
This and all other high level Trellis functions have several
arguments in common. These are extensively documented only in the
help page for
xyplot, which should be consulted to learn more