# panel.functions

##### Useful Panel Functions

These are predefined panel functions available in lattice for use in constructing new panel functions (usually on-the-fly).

- Keywords
- dplot

##### Usage

```
panel.abline(a = NULL, b = 0,
h = NULL, v = NULL,
reg = NULL, coef = NULL,
col, col.line, lty, lwd, alpha, type,
...)
```panel.curve(expr, from, to, n = 101,
curve.type = "l",
col, lty, lwd, type,
...)
panel.rug(x = NULL, y = NULL,
regular = TRUE,
start = if (regular) 0 else 0.97,
end = if (regular) 0.03 else 1,
x.units = rep("npc", 2),
y.units = rep("npc", 2),
col, lty, lwd, alpha,
...)
panel.average(x, y, fun = mean, horizontal = TRUE,
lwd, lty, col, col.line, type,
...)
panel.linejoin(x, y, fun = mean, horizontal = TRUE,
lwd, lty, col, col.line, type,
...)panel.fill(col, border, ...)
panel.grid(h=3, v=3, col, col.line, lty, lwd, ...)
panel.lmline(x, y, ...)
panel.loess(x, y, span = 2/3, degree = 1,
family = c("symmetric", "gaussian"),
evaluation = 50,
lwd, lty, col, col.line, type,
horizontal = FALSE,
...)
panel.mathdensity(dmath = dnorm, args = list(mean=0, sd=1),
n = 50, col, col.line, lwd, lty, type,
...)

##### Details

`panel.abline`

adds a line of the form `y=a+bx`

or vertical
and/or horizontal lines. Graphical parameters are obtained from
`reference.line`

for panel.grid, and `add.line`

for the
others (can be set using `trellis.par.set`

)

`panel.curve`

adds a curve, similar to what `curve`

does
with `add = TRUE`

. Graphical parameters for the line are obtained
from the `add.line`

setting.

`panel.average`

treats one of x and y as a factor (according to
the value of `horizontal`

), calculates `fun`

applied to the
subsets of the other variable determined by each unique value of the
factor, and joins them by a line. Can be used in conjunction with
`panel.xyplot`

and more commonly with panel.superpose to produce
interaction plots. See `xyplot`

documentation for an
example. `panel.linejoin`

is an alias for `panel.average`

retained for back-compatibility and may go away in future.

`panel.mathdensity`

plots a (usually theoretical) probability
density function. This can be useful in conjunction with
`histogram`

and `densityplot`

to visually estimate goodness
of fit (note, however, that `qqmath`

is more suitable for this).

`panel.rug`

adds a *rug* representation of the (marginal)
data to the panel, much like `rug`

.

`panel.lmline(x, y)`

is equivalent to
`panel.abline(lm(y~x))`

.

##### See Also

`loess.smooth`

,
`panel.axis`

, `panel.identify`

`identify`

, `trellis.par.get`

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