# panel.mysymbols: Draw Symbols (User Defined) on a Lattice Plot In TeachingDemos: Demonstrations for Teaching and Learning

## Description

This function draws symbols on a lattice plot. It is similar to the builtin `symbols` function with the difference that it plots symbols defined by the user rather than a prespecified set of symbols.

## Usage

 ```1 2``` ```panel.my.symbols(x, y, symb, inches=1, polygon=FALSE, ..., symb.plots=FALSE, subscripts, MoreArgs) ```

## Arguments

 `x, y` The `x` and `y` coordinates for the position of the symbols to be plotted. These can be specified in any way which is accepted by `xy.coords`. `symb` Either a matrix, list, or function defining the symbol to be plotted. If it is a matrix or list it needs to be formatted that it can be passed directly to the `llines` function. It then defines the shape of the symbol on on a range/domain of -1 to 1. If this is a function it can either return a matrix or list as above (points on the range/domain of -1 to 1). `inches` The size of the square containing the symbol in inches (note: unlike `symbols` this cannot be `FALSE`). `polygon` If TRUE, use `lpolygon` function to plot rather than the `llines` function. `symb.plots` Currently not implemented. `...` Additional arguments will be replicated to the same length as `x` then passed to `symb` (if `symb` is a function) and/or the `lines` function (one value per symbol drawn). `subscripts` subscripts for the current panel `MoreArgs` A list with any additional arguments to be passed to the `symb` function (as is, without being replicated/split).

## Details

The `symb` argument can be a 2 column matrix or a list with components 'x' and 'y' that defines points on the interval [-1,1] that will be connected with lines to draw the symbol. If you want a closed polygon then be sure to replicate the 1st point as the last point or use the `polygon` option.

If any point contains an NA then the line will not be drawn to or from that point. This can be used to create a symbol with disjoint parts that should not be connected.

If `symb` is a function then any unmatched arguments that end up in the '...' argument will be replicated to the same length as 'x' (using the `rep` function) then the values will be passed one at a time to the `symb` function. If `MoreArgs` is specified, the elements of it will also be passed to `symb` without modification. The `symb` function can either return a matrix or list with the points that will then be passed to the `llines` function (see above).

## Value

This function is run for its side effect of plotting, it returns an invisible NULL.

## Note

Plotting coordinates and sizes are based on the size of the device at the time the function is called. If you resize the device after plotting, all bets are off.

## Author(s)

Greg Snow [email protected]

`symbols`, `my.symbols`, `subplot`, `mapply`, `ms.polygram`, `lines`
 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30``` ```if(require(lattice)) { tmpdf <- data.frame( x=1:10, y=1:10, g=rep( c("A","B"), each=5 ), z=c(1:5,5:1) ) xyplot( y ~ x, tmpdf, panel=panel.my.symbols, symb=ms.female, inches=0.3 ) xyplot( y ~ x | g, tmpdf, panel=panel.my.symbols, symb=ms.male, inches=0.3) xyplot( y ~ x, tmpdf, panel=panel.superpose, groups=g, panel.groups= function(group.number, ...) { if(group.number==1) { panel.my.symbols(..., symb=ms.male) } else { panel.my.symbols(..., symb=ms.female) } }, inches=0.3 ) xyplot( y ~ x, tmpdf, panel=panel.my.symbols, symb=ms.polygram, n=tmpdf\$z, inches=0.3) xyplot( y ~ x | g, tmpdf, panel=panel.my.symbols, symb=ms.polygram, n=tmpdf\$z, inches=0.3) xyplot( y ~ x, tmpdf, panel=panel.superpose, groups=g, panel.groups = panel.my.symbols, inches=0.3, symb=ms.polygon, n=tmpdf\$z, polygon=TRUE, adj=rep(c(0,pi/4),5) ) } ```