# 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, b, ...)
panel.abline(coef, ...)
panel.abline(reg, ...)
panel.abline(h= ,v= , ...)
panel.curve(expr, from, to, n = 101,
curve.type = "l", ...)
panel.rug(x = NULL, y = NULL,
regular = TRUE, start, end, ...)
panel.fill(col="grey", ...)
panel.grid(h=3, v=3, ...)
panel.lmline(x,y,...) = panel.abline(lm(y~x), ...)
panel.loess(x, y, span = 2/3, degree = 1,
family = c("symmetric", "gaussian"),
evaluation = 50, ...)
panel.linejoin(x, y, fun = mean, horizontal = TRUE, ...)
panel.mathdensity(dmath = dnorm, args = list(mean=0, sd=1))
```

##### Arguments

- x, y
- variables defining the contents of the panel
- a, b
- Coefficients of the line to be added
- coef
- Coefficients of the line to be added as a length 2 vector
- reg
- A regression object. The corresponding fitted line will be drawn
- h,v
- For
`panel.abline`

, numerical vectors giving y and x locations respectively of horizontal and vertical lines to be added to the plot. For panel.grid, number of horizontal and vertical reference lines to be added to the plot; h=-1 an - expr
- expression as a function of x or a function to plot as a curve
- n
- the number of points to use for drawing the curve
- regular
- logical indicating whether `rug' to be drawn on the regular side (left / bottom) or not (right / top)
- start, end
- endpoints of rug segments, in normalized parent coordinates (between 0 and 1). Defaults depend on value of regular, and cover 3% of the panel width and height
- from, to
- optional lower and upper x-limits of curve. If missing, limits of current panel are used
- curve.type
- type of curve ('p' for points, etc), passed to
`llines`

- col
- color
- span, degree, family, evaluation
- arguments to
`loess.smooth`

, around which`panel.loess`

is essentially a wrapper - fun
- the function that will be applied to the subset of x(y) determined by the unique values of y(x)
- horizontal
- logical. If FALSE, the plot is `transposed' in the
sense that the behaviours of x and y are switched. x is now
the `factor'. Interpretation of other arguments change
accordingly. See documentation of
`bwplot`

for a fuller expla - dmath
- A vectorized function that produces density values
given a numeric vector named
`x`

, e.g.,`dnorm`

- args
- list giving additional arguments to be passed to dmath
- ...
- graphical parameters can be supplied. see function
definition for details. Color can usually be specified by
`col, col.line`

and`col.symbol`

, the last two overriding the first for lines and points respectively.

##### 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.linejoin`

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.mathdensity`

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

and `densityplot`

to visually estimate goodness of fit.

`panel.axis`

draws axis tick marks INSIDE a panel. It honours the
(native) axis scales within the panel, but the locations need to be
explicitly specified. Used in `panel.pairs`

for
`splom`

.

`panel.identify`

is similar to `identify`

. When
called as part of the panel function, it waits for the user to
identify points (in the panel being drawn) via mouse clicks.
Clicks other than left-clicks terminate the procedure. It is less
sophisticated than `identify`

in the sense that it does not keep
track of points already identified.

##### synopsis

panel.abline(a, b = NULL, h = numeric(0), v = numeric(0), col, col.line = add.line$col, lty = add.line$lty, lwd = add.line$lwd, ...) panel.curve(expr, from, to, n = 101, curve.type = "l", col = add.line$col, lty = add.line$lty, lwd = add.line$lwd, type = NULL, ...) panel.rug(x = NULL, y = NULL, regular = TRUE, start = if (regular) 0 else 0.97, end = if (regular) 0.03 else 1, col, ...) panel.linejoin(x, y, fun = mean, horizontal = TRUE, lwd = reference.line$lwd, lty = reference.line$lty, col, col.line = reference.line$col, ...)

##### See Also

*Documentation reproduced from package lattice, version 0.10-10, License: GPL version 2 or later*