Using Unicode inside R's expression() command

Question

I'm using expression() in R plots in order to get italicized text. But it appears as if I cannot use Unicode symbols inside expression outside of ASCII characters. Is there some way I can work around this? My goal is to get the fi ligature in various labels in my R barplots (together with italicized text).

I'm using R for Windows version 3.0.2.

CairoPDF(file = "Ligature1.pdf")
plot.new()
text(x =.5, y = .5, labels = "fi", family = "Times New Roman")
dev.off()

CairoPDF(file = "Ligature2.pdf")
plot.new()
text(x =.5, y = .5, labels = expression(paste(italic(m), "u", "fi", italic(m), sep = "")), family = "Times New Roman")
dev.off()

Answer 1

You asked for a work-around. That is all this is. The italic part needs expression, but the "fi" part does not, so print them separately.

plot.new()
offset1 = strwidth(expression(paste(italic(m), "u")), units="figure")
text(x =.5, y = .5, labels = expression(paste(italic(m), "u", sep="")))
text(x =.5+offset1, y = .5, labels ="fi")
offset2 = strwidth("fi ")
text(x =.5+offset1+offset2, y = .5, labels = expression(italic(m)))

But notice that something is not quite right about the spacing of the "fi", so when I computed the width on the screen, I cheated and computed the width of "fi " (with an extra blank). Without the extra spacing, the second italic(m) overlapped the "fi".

Not pretty, but it produces the desired result under Windows.