# qqmath

##### Q-Q Plot with Theoretical Distribution

Quantile-Quantile plot of a sample and a theoretical distribution

- Keywords
- dplot

##### Usage

`qqmath(x, data, ...)`
## S3 method for class 'formula':
qqmath(x,
data,
allow.multiple = is.null(groups) || outer,
outer = !is.null(groups),
distribution = qnorm,
f.value = NULL,
auto.key = FALSE,
aspect = "fill",
panel = lattice.getOption("panel.qqmath"),
prepanel = NULL,
scales, strip, groups,
xlab, xlim, ylab, ylim,
drop.unused.levels = lattice.getOption("drop.unused.levels"),
...,
lattice.options = NULL,
default.scales = list(),
subscripts,
subset)
## S3 method for class 'numeric':
qqmath(x, data = NULL, ylab, \dots)

##### Details

`qqmath`

produces a Q-Q plot of the given sample and a
theoretical distribution. The default behaviour of `qqmath`

is
different from the corresponding S-PLUS function, but is similar to
`qqnorm`

. See the entry for `f.value`

for specifics.

The implementation details are also different from S-PLUS. In
particular, all the important calculations are done by the panel (and
prepanel function) and not `qqmath`

itself. In fact, both the
arguments `distribution`

and `f.value`

are passed unchanged
to the panel and prepanel function. This allows, among other things,
display of grouped Q-Q plots, which are often useful. See the help
page for `panel.qqmath`

for further details.

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
detailed usage.

##### Value

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.

##### See Also

`xyplot`

, `panel.qqmath`

,
`panel.qqmathline`

, `prepanel.qqmathline`

,
`Lattice`

, `quantile`

##### Examples

```
qqmath(~ rnorm(100), distribution = function(p) qt(p, df = 10))
qqmath(~ height | voice.part, aspect = "xy", data = singer,
prepanel = prepanel.qqmathline,
panel = function(x, ...) {
panel.qqmathline(x, ...)
panel.qqmath(x, ...)
})
vp.comb <-
factor(sapply(strsplit(as.character(singer$voice.part), split = ""),
"[", 1),
levels = c("Bass", "Tenor", "Alto", "Soprano"))
vp.group <-
factor(sapply(strsplit(as.character(singer$voice.part), split = ""),
"[", 2))
qqmath(~ height | vp.comb, data = singer,
groups = vp.group, auto.key = list(space = "right"),
aspect = "xy",
prepanel = prepanel.qqmathline,
panel = function(x, ...) {
panel.qqmathline(x, ...)
panel.qqmath(x, ...)
})
```

*Documentation reproduced from package lattice, version 0.17-10, License: GPL (>= 2)*