# prepanel.functions: Useful Prepanel Function for Lattice In lattice: Trellis Graphics for R

## Description

These are predefined prepanel functions available in Lattice.

## Usage

 ``` 1 2 3 4 5 6 7 8 9 10``` ```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`

## Author(s)

Deepayan Sarkar Deepayan.Sarkar@R-project.org

Lattice, `xyplot`, `banking`, `panel.loess`, `panel.spline`.