# F_3_prepanel.functions

##### Useful Prepanel Function for Lattice

These are predefined prepanel functions available in Lattice.

- Keywords
- dplot

##### Usage

```
prepanel.lmline(x, y, …)
prepanel.qqmathline(x, y = x, distribution = qnorm,
probs = c(0.25, 0.75), qtype = 7,
groups, subscripts,
…)
prepanel.loess(x, y, span, degree, family, evaluation,
horizontal = FALSE, …)
prepanel.spline(x, y, npoints = 101,
horizontal = FALSE, …,
keep.data = FALSE)
```

##### Arguments

- x, y
x and y values, numeric or factor

- distribution
quantile function for theoretical distribution. This is automatically passed in when this is used as a prepanel function in

`qqmath`

.- qtype
type of

`quantile`

- probs
numeric vector of length two, representing probabilities. If used with

`aspect="xy"`

, the aspect ratio will be chosen to make the line passing through the corresponding quantile pairs as close to 45 degrees as possible.- span, degree, family, evaluation
Arguments controlling the underlying

`loess`

smooth.- horizontal, npoints
See documentation for corresponding panel function.

- keep.data
Ignored. Present to capture argument of the same name in

`smooth.spline`

.- groups, subscripts
See

`xyplot`

. Whenever appropriate, calculations are done separately for each group and then combined.- …
Other arguments. These are passed on to other functions if appropriate (in particular,

`smooth.spline`

), and ignored otherwise.

##### Details

All these prepanel functions compute the limits to be large enough to contain all points as well as the relevant smooth.

In addition, `prepanel.lmline`

computes the `dx`

and
`dy`

such that it reflects the slope of the linear regression
line; for `prepanel.qqmathline`

, this is the slope of the line
passing through the quantile pairs specified by `probs`

. For
`prepanel.loess`

and `prepanel.spline`

, `dx`

and
`dy`

reflect the piecewise slopes of the nonlinear smooth.

##### Value

usually a list with components `xlim`

, `ylim`

, `dx`

and
`dy`

, the first two being used to calculate panel axes limits,
the last two for banking computations. The form of these components
are described under `xyplot`

. There are also several
prepanel functions that serve as the default for high level functions,
see `prepanel.default.xyplot`

##### See Also

*Documentation reproduced from package lattice, version 0.20-41, License: GPL (>= 2)*