mtext 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, padj = NA, cex = NA, col = NA, font = NA, ...)

Arguments

text	a character or expression vector specifying the text to be written. Other objects are coerced by as.graphicsAnnot.
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 of each string in user coordinates. If the component of at corresponding to a particular text item is not a finite value (the default), the location will be determined by adj.
adj	adjustment for each string in reading direction. For strings parallel to the axes, adj = 0 means left or bottom alignment, and adj = 1 means right or top alignment. If adj is not a finite value (the default), the value of par("las") determines the adjustment. For strings plotted parallel to the axis the default is to centre the string.
padj	adjustment for each string perpendicular to the reading direction (which is controlled by adj). For strings parallel to the axes, padj = 0 means right or top alignment, and padj = 1 means left or bottom alignment. If padj is not a finite value (the default), the value of par("las") determines the adjustment. For strings plotted perpendicular to the axis the default is to centre the string.
cex	character expansion factor. NULL and NA are equivalent to 1.0. This is an absolute measure, not scaled by par("cex") or by setting par("mfrow") or par("mfcol"). Can be a vector.
col	color to use. Can be a vector. NA values (the default) mean use par("col").
font	font for text. Can be a vector. NA values (the default) mean use par("font").
...	Further graphical parameters (see par), including family, las and xpd. (The latter defaults to the figure region unless outer = TRUE, otherwise the device region. It can only be increased.)

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 differs here from other implementations of S.

All of the named arguments 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 justification is to place the end of the string nearest the axis on the specified line. (Note that this differs from S, which uses srt if at is supplied and las if it is not. Parameter srt is ignored in R.)

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.

Graphics parameter "ylbias" (see par) determines how the text baseline is placed relative to the nominal line.

Side Effects

The given text is written onto the current plot.

References

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

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)