Italics on some of the legend labels

[Luciano Selzer]

Hi Group, I wanted to know if it's possible to make some of the labels of the legend have italic while the others have the normal font. Something like the code below, except it doesn't work. Is it possible to do this? If so, how?

Thank you

dsamp <- diamonds[sample(nrow(diamonds), 1000), ] 
d <- qplot(carat, price, data=dsamp, colour=clarity)

lab <- levels(dsamp$clarity)
lab_italics <- c(expression(italic("Text1")), expression(italic("Text2")), lab[3:length(lab)])

d + scale_colour_hue(breaks=lab, labels=lab_italics)

Luciano

[baptiste auguie]

Hi,

For a reason that is just not clear to me the following works,

l1 <- expression(italic("Text1"), italic("Text2"), lab[3], lab[4],
lab[5], lab[6], lab[7], lab[8])

d + scale_colour_hue(breaks=lab, labels=l1)

while a seemingly similar expression does not,

l1 <- as.expression(do.call(c, list(expression(italic("Text1"),
italic("Text2")), lab[3:length(lab)])))

I hope R help gurus could explain that one.

Best,

baptiste

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[baptiste auguie]

Whoops, the first one doesn't even work properly. Sorry for the noise.

baptiste

[takahashi kohske]

Hi,

easy workaround is using plain annotation for the other labels instead
of simple text:

d + scale_colour_hue(breaks=lab,
labels=parse(text=c(paste('italic(',lab[1:3],')'),
paste('plain(',lab[-c(1:3)],')'))))

it does works in my test.

But I could not find out what the following code actually does in
build_legend, which induced the error when the labels includes some
(but not all) expression:

numeric_labels <- all(sapply(mapping$.label, is.language)) ||
suppressWarnings(all(!is.na(sapply(mapping$.label, "as.numeric"))))
hpos <- numeric_labels * 1

the first all() returns FALSE because some of labels are character,
and then as.numeric() induces error because the other of labels are
expression.

2010/3/9 Luciano Selzer <luciano...@gmail.com>:

[Hadley Wickham]

That code tries to figure out whether to right or left align the
labels. I never considered the case of mixed text and expressions.

Hadley

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Assistant Professor / Dobelman Family Junior Chair
Department of Statistics / Rice University
http://had.co.nz/