| strwidth {graphics} | R Documentation |
Plotting Dimensions of Character Strings and Math Expressions
Description
These functions compute the width or height, respectively, of the
given strings or mathematical expressions s[i] on
the current plotting device in user coordinates, inches
or as fraction of the figure width par("fin").
Usage
strwidth(s, units = "user", cex = NULL, font = NULL, vfont = NULL, ...)
strheight(s, units = "user", cex = NULL, font = NULL, vfont = NULL, ...)
Arguments
s |
a character or expression vector whose dimensions
are to be determined. Other objects are coerced by
|
units |
character indicating in which units |
cex |
numeric character expansion factor; multiplied
by |
font, vfont, ... |
additional information about the font,
possibly including the graphics parameter |
Details
Note that the ‘height’ of a string is determined only by the
number of linefeeds ("\n", aka “newline”s) it contains: it is the (number of
linefeeds - 1) times the line spacing plus the height of "M" in
the selected font. For an expression it is the height of the
bounding box as computed by plotmath. Thus in both cases it is
an estimate of how far above the final baseline the typeset
object extends. (It may also extend below the baseline.) The
inter-line spacing is controlled by cex,
par("lheight") and the ‘point size’ (but not the
actual font in use).
Measurements in "user" units (the default) are only available
after plot.new has been called – otherwise an error is
thrown.
Value
Numeric vector with the same length as s, giving the estimate of
width or height for each s[i]. NA strings are given
width and height 0 (as they are not plotted).
See Also
Examples
str.ex <- c("W","w","I",".","WwI.")
op <- par(pty = "s"); plot(1:100, 1:100, type = "n")
sw <- strwidth(str.ex); sw
all.equal(sum(sw[1:4]), sw[5])
#- since the last string contains the others
sw.i <- strwidth(str.ex, "inches"); 25.4 * sw.i # width in [mm]
unique(sw / sw.i)
# constant factor: 1 value
mean(sw.i / strwidth(str.ex, "fig")) / par('fin')[1] # = 1: are the same
## See how letters fall in classes
## -- depending on graphics device and font!
all.lett <- c(letters, LETTERS)
shL <- strheight(all.lett, units = "inches") * 72 # 'big points'
table(shL) # all have same heights ...
mean(shL)/par("cin")[2] # around 0.6
(swL <- strwidth(all.lett, units = "inches") * 72) # 'big points'
split(all.lett, factor(round(swL, 2)))
sumex <- expression(sum(x[i], i=1,n), e^{i * pi} == -1)
strwidth(sumex)
strheight(sumex)
par(op) #- reset to previous setting