R: Write Text into the Margins of a Plot

mtext {base} | R Documentation

## Write Text into the Margins of a Plot

### Description

Text is written in one of the four margins of the current figure region or one of the outer margins of the device region.

### Usage

    mtext(text, side = 3, line = 0, outer = FALSE, at = NA,
          adj = NA, cex = NA, col = NA, font = NA, vfont = NULL, ...)

### Arguments

`text` | one or more character strings or expressions.
`side` | on which side of the plot (1=bottom, 2=left, 3=top, 4=right).
`line` | on which MARgin line, starting at 0 counting outwards.
`outer` | use outer margins if available.
`at` | give location in user-coordinates. If `length(at)==0` (the default), the location will be determined by `adj`.
`adj` | adjustment for each string. For strings parallel to the axes, `adj=0` means left or bottom alignment, and `adj=1` means right or top aligment. If `adj` is not a finite value (the default), the value `par("las")` determines the adjustment. For strings plotted parallel to the axis the default is to centre the string.
`...` | Further graphical parameters (see `text` and `par`) ; currently supported are:
`cex` | character expansion factor (default = 1).
`col` | color to use.
`font` | font for text.
`vfont` | vector font for text.

### Details

The ``user coordinates'' in the outer margins always range from zero to one, and are not affected by the user coordinates in the figure region(s) — R is differing here from other implementations of S.

The arguments `side`, `line`, `at`, `at`, `adj`, the further graphical parameters and even `outer` can be vectors, and recycling will take place to plot as many strings as the longest of the vector arguments. Note that a vector `adj` has a different meaning from `text`.

`adj = 0.5` will centre the string, but for `outer=TRUE` on the device region rather than the plot region.

Parameter `las` will determine the orientation of the string(s). For strings plotted perpendicular to the axis the default justifcation is to place the end of the string nearest the axis on the specified line.

Note that if the text is to be plotted perpendicular to the axis, `adj` determines the justification of the string and the position along the axis unless `at` is specified.

### Side Effects

The given text is written onto the current plot.

### See Also

`title`, `text`, `plot`, `par`; `plotmath` for details on mathematical annotation.

### Examples

    plot(1:10, (-4:5)^2, main="Parabola Points", xlab="xlab")
    mtext("10 of them")
    for(s in 1:4)
        mtext(paste("mtext(..., line= -1, {side, col, font} = ",s,
              ", cex = ", (1+s)/2, ")"), line = -1,
              side=s, col=s, font=s, cex= (1+s)/2)
    mtext("mtext(..., line= -2)", line = -2)
    mtext("mtext(..., line= -2, adj = 0)", line = -2, adj =0)
    ##--- log axis :
    plot(1:10, exp(1:10), log='y', main="log='y'", xlab="xlab")
    for(s in 1:4) mtext(paste("mtext(...,side=",s,")"), side=s)

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