R: Draw symbols on a plot

symbols {base} | R Documentation

## Draw symbols 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, circles, squares, rectangles, stars,
            thermometers, boxplots, inches=TRUE, add=FALSE,
            fg=1, bg=NA, xlab = NULL, ylab = NULL, main = NULL,
            xlim = NULL, ylim = NULL, ...)

### Arguments

`x` | a vector giving the x coordinates of the symbols.
`y` | a vector giving the y coordinates of the symbols.
`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 rectangle symbols.
`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 from their base to this proportion of their height. If there are four columns, the third and fourth columns are taken as proportions. The thermometers are filled between these two proportions of their heights.
`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` | If `inches` is `FALSE`, the units are taken to be those of the x axis. If `inches` is `TRUE`, the symbols are scaled so that the largest symbol is one inch in height. If a number is given the symbols are scaled to make largest symbol this height in inches.
`add` | if `add` is `TRUE`, the symbols are added to an existing plot, otherwise a new plot is created.
`fg` | colors the symbols are to be drawn in (the default is the value of the `col` graphics parameter).
`bg` | if specified, the symbols are filled with this color. The default is to leave the symbols unfilled.
`xlab` | the x label of the plot if `add` is not true; this applies to the following arguments as well. Defaults to the `deparse`d expression used for `x`.
`ylab` | the y label of the plot.
`main` | a main title for the plot.
`xlim` | numeric of length 2 giving the x limits for the plot.
`ylim` | numeric of length 2 giving the y limits for the plot.
`...` | graphics parameters can also be passed to this function.

### 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 rays which are `NA` is reset to zero.

### References

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

### See Also

`stars` for drawing stars with a bit more flexibility; `sunflowerplot`.

### 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)

    data(trees)
    ## Note that  example(trees)  shows more sensible plots!
    N <- nrow(trees)
    attach(trees)
    ## Girth is diameter in inches
    symbols(Height, Volume, circles=Girth/24, inches=FALSE,
            main="Trees' Girth")# xlab and ylab automatically
    ## Colors 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"); detach()

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