R: Plot Annotation

title {graphics} | R Documentation

## Plot Annotation

### Description

This function can be used to add labels to a plot. Its first four principal arguments can also be used as arguments in most high-level plotting functions. They must be of type `character` or `expression`. In the latter case, quite a bit of mathematical notation is available such as sub- and superscripts, greek letters, fractions, etc: see plotmath

### Usage

    title(main = NULL, sub = NULL, xlab = NULL, ylab = NULL,
          line = NA, outer = FALSE, ...)

### Arguments

`main` | The main title (on top) using font and size (character expansion) `par("font.main")` and color `par("col.main")`.
`sub` | Sub-title (at bottom) using font and size `par("font.sub")` and color `par("col.sub")`.
`xlab` | X axis label using font and character expansion `par("font.lab")` and color `par("col.lab")`.
`ylab` | Y axis label, same font attributes as `xlab`.
`line` | specifying a value for `line` overrides the default placement of labels, and places them this many lines outwards from the plot edge.
`outer` | a logical value. If `TRUE`, the titles are placed in the outer margins of the plot.
`...` | further graphical parameters from `par`. Use e.g., `col.main` or `cex.sub` instead of just `col` or `cex`. `adj` controls the justification of the titles. `xpd` can be used to set the clipping region: this defaults to the figure region unless `outer = TRUE`, otherwise the device region and can only be increased. `mgp` controls the default placing of the axis titles.

### Details

The labels passed to `title` can be character strings or language objects (names, calls or expressions), or a list containing the string to be plotted, and a selection of the optional modifying graphical parameters `cex=`, `col=` and `font=`. Other objects will be coerced by `as.graphicsAnnot`.

The position of `main` defaults to being vertically centered in (outer) margin 3 and justified horizontally according to `par("adj")` on the plot region (device region for `outer = TRUE`).

The positions of `xlab`, `ylab` and `sub` are `line` (default for `xlab` and `ylab` being `par("mgp")[1]` and increased by `1` for `sub`) lines (of height `par("mex")`) into the appropriate margin, justified in the text direction according to `par("adj")` on the plot/device region.

### References

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

### See Also

`mtext`, `text`; `plotmath` for details on mathematical annotation.

### Examples

    plot(cars, main = "") # here, could use main directly
    title(main = "Stopping Distance versus Speed")

    plot(cars, main = "")
    title(main = list("Stopping Distance versus Speed", cex = 1.5,
                      col = "red", font = 3))

    ## Specifying "..." :
    plot(1, col.axis = "sky blue", col.lab = "thistle")
    title("Main Title", sub = "sub title",
          cex.main = 2,   font.main= 4, col.main= "blue",
          cex.sub = 0.75, font.sub = 3, col.sub = "red")

    x <- seq(-4, 4, len = 101)
    y <- cbind(sin(x), cos(x))
    matplot(x, y, type = "l", xaxt = "n",
            main = expression(paste(plain(sin) * phi, "  and  ",
                                    plain(cos) * phi)),
            ylab = expression("sin" * phi, "cos" * phi), # only 1st is taken
            xlab = expression(paste("Phase Angle ", phi)),
            col.main = "blue")
    axis(1, at = c(-pi, -pi/2, 0, pi/2, pi),
         labels = expression(-pi, -pi/2, 0, pi/2, pi))
    abline(h = 0, v = pi/2 * c(-1,1), lty = 2, lwd = .1, col = "gray70")

[Package graphics version 3.1.2 Index]