strwidth {base}

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)
strheight(s, units = "user", cex = NULL)

Arguments

s	character vector or expressions whose string widths in plotting units are to be determined.
units	character indicating in which units s is measured; must be one of "user", "inches", "figure" .
cex	character expansion to which is applies. Per default, the current par("cex") is used.

Value

integer vector with the same length as s, giving the width for each s[i].

See Also

text, nchar

Examples

str.ex <- c("W","w","I",".","WwI.")
op <- par(pty='s'); plot(1:100,1:100); par('usr')
sw <- strwidth(str.ex); sw
sum(sw[1:4] == sw[5])#- since the last string contains the others
sw / strwidth(str.ex, cex = .5)
# between 1.5 and 4.2 (!),  font dependent

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")
table(shL)# all have same heights ..
mean(shL) / par("cin")[2] # should be 1 (exactly?)

swL <- strwidth(all.lett)
swL <- 3 * swL / min(swL)
all(swL == round(swL))#- TRUE !
swL <- as.integer(swL)
n.classes <- length(tL <- table(swL)); tL
iL <- order(swL)
structure(swL[iL], names = all.lett[iL])
lett.classes <- structure(vector("list", n.classes), names= names(tL))
for(i in 1:n.classes)
  lett.classes[[i]] <- all.lett[swL == as.numeric(names(tL)[i])]
lett.classes

sumex <- expression(sum(x[i], i=1,n), e^{i * pi} == -1)
strwidth(sumex)
strheight(sumex)

rm(sumex); par(op)#- reset to previous setting

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