symbols {graphics} R Documentation

Draw Symbols (Circles, Squares, Stars, Thermometers, Boxplots) on a Plot

Description

This function draws symbols on a plot. One of six symbols; circles, squares, rectangles, stars, thermometers, and boxplots, can be plotted at a specified set of x and y coordinates. Specific aspects of the symbols, such as relative size, can be customized by additional parameters.

Usage

```symbols(x, y = NULL, circles, squares, rectangles, stars,
thermometers, boxplots, inches = TRUE, add = FALSE,
fg = par("col"), bg = NA, xlab = NULL, ylab = NULL, main = NULL,
xlim = NULL, ylim = NULL, ...)
```

Arguments

 `x, y` the x and y co-ordinates for the centres of the symbols. They can be specified in any way which is accepted by `xy.coords`. `circles` a vector giving the radii of the circles. `squares` a vector giving the length of the sides of the squares. `rectangles` a matrix with two columns. The first column gives widths and the second the heights of rectangles. `stars` a matrix with three or more columns giving the lengths of the rays from the center of the stars. `NA` values are replaced by zeroes. `thermometers` a matrix with three or four columns. The first two columns give the width and height of the thermometer symbols. If there are three columns, the third is taken as a proportion: the thermometers are filled (using colour `fg`) from their base to this proportion of their height. If there are four columns, the third and fourth columns are taken as proportions and the thermometers are filled between these two proportions of their heights. The part of the box not filled in `fg` will be filled in the background colour (default transparent) given by `bg`. `boxplots` a matrix with five columns. The first two columns give the width and height of the boxes, the next two columns give the lengths of the lower and upper whiskers and the fifth the proportion (with a warning if not in [0,1]) of the way up the box that the median line is drawn. `inches` `TRUE`, `FALSE` or a positive number. See Details. `add` if `add` is `TRUE`, the symbols are added to an existing plot, otherwise a new plot is created. `fg` colour(s) the symbols are to be drawn in. `bg` if specified, the symbols are filled with colour(s), the vector `bg` being recycled to the number of symbols. The default is to leave the symbols unfilled. `xlab` the x label of the plot if `add` is not true. Defaults to the `deparse`d expression used for `x`. `ylab` the y label of the plot. Unused if `add = TRUE`. `main` a main title for the plot. Unused if `add = TRUE`. `xlim` numeric vector of length 2 giving the x limits for the plot. Unused if `add = TRUE`. `ylim` numeric vector of length 2 giving the y limits for the plot. Unused if `add = TRUE`. `...` graphics parameters can also be passed to this function, as can the plot aspect ratio `asp` (see `plot.window`).

Details

Observations which have missing coordinates or missing size parameters are not plotted. The exception to this is stars. In that case, the length of any ray which is `NA` is reset to zero.

Argument `inches` controls the sizes of the symbols. If `TRUE` (the default), the symbols are scaled so that the largest dimension of any symbol is one inch. If a positive number is given the symbols are scaled to make largest dimension this size in inches (so `TRUE` and `1` are equivalent). If `inches` is `FALSE`, the units are taken to be those of the appropriate axes. (For circles, squares and stars the units of the x axis are used. For boxplots, the lengths of the whiskers are regarded as dimensions alongside width and height when scaling by `inches`, and are otherwise interpreted in the units of the y axis.)

Circles of radius zero are plotted at radius one pixel (which is device-dependent).

References

Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.

W. S. Cleveland (1985) The Elements of Graphing Data. Monterey, California: Wadsworth.

Murrell, P. (2005) R Graphics. Chapman & Hall/CRC Press.

`stars` for drawing stars with a bit more flexibility. If are about doing “bubble plots” by `symbols(*,circles=*)`, you should really consider using `sunflowerplot` instead.

Examples

```x <- 1:10
y <- sort(10*runif(10))
z <- runif(10)
z3 <- cbind(z, 2*runif(10), runif(10))
symbols(x, y, thermometers=cbind(.5, 1, z), inches=.5, fg = 1:10)
symbols(x, y, thermometers = z3, inches=FALSE)
text(x,y, apply(format(round(z3, dig=2)), 1, paste, collapse = ","),
adj = c(-.2,0), cex = .75, col = "purple", xpd=NA)

## Note that  example(trees)  shows more sensible plots!
N <- nrow(trees)
with(trees, {
## Girth is diameter in inches
symbols(Height, Volume, circles=Girth/24, inches=FALSE,
main="Trees' Girth")# xlab and ylab automatically
## Colours too:
palette(rainbow(N, end = 0.9))
symbols(Height, Volume, circles=Girth/16, inches=FALSE, bg = 1:N,
fg="gray30", main="symbols(*, circles=Girth/16, bg = 1:N)")
palette("default")
})
```

[Package graphics version 2.5.0 Index]