You can edit the grobs in the gtable,
ggplot(diamonds, aes(carat, price, fill = ..density..)) +
xlim(0, 2) + stat_binhex(na.rm = TRUE) + facet_wrap(~ color, ncol = 4)
for(ii in 1:7)
grid.gedit(gPath(paste0("strip_t-", ii), "strip.text"),
grep=TRUE, label=bquote(gamma[.(ii)]))
alternatively, if you want to save a grob,
g <- ggplotGrob(d)
gg <- g$grobs
strips <- grep("strip_t", names(gg))
for(ii in strips)
gg[[ii]] <- editGrob(getGrob(gg[[ii]], "strip.text",
grep=TRUE, global=TRUE),
label=bquote(gamma[.(ii)]))
g$grobs <- gg
using ggsave would require extra (ugly) work, since one has to fool the test for class ggplot... I reckon it will be easier to call pdf() ; grid.draw(g); dev.off()
explicitly.
Edit by Roland:
I made a small correction and wrapped it in a function:
facet_wrap_labeller <- function(gg.plot,labels=NULL) {
#works with R 3.0.1 and ggplot2 0.9.3.1
require(gridExtra)
g <- ggplotGrob(gg.plot)
gg <- g$grobs
strips <- grep("strip_t", names(gg))
for(ii in seq_along(labels)) {
modgrob <- getGrob(gg[[strips[ii]]], "strip.text",
grep=TRUE, global=TRUE)
gg[[strips[ii]]]$children[[modgrob$name]] <- editGrob(modgrob,label=labels[ii])
}
g$grobs <- gg
class(g) = c("arrange", "ggplot",class(g))
g
}
This allows to print nicely and even ggsave
can be used.
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