wrapping legend text to fit the plot window

Question

I am using ggplot to chart some data and I noticed that legends text are very long and not fitting the window.

+ opts(legend.position = 'bottom', legend.direction = 'horizontal', size=0.1)  +
    guides(colour = guide_legend(nrow = 3), size=1) 

Is there an option in ggplot to wrap the legend text to fit the window.

Answer 1

Not as far as I know, so I have resorted to a workaround using strwidth(), which calculates the width of text in base graphics.

title <- "This is a really excessively wide title for a plot, especially since it probably won't fit"

Use par("din") to get the width of the device, and strwidth() to calculate the text size:

par("din")[1]
[1] 8.819444
strwidth(title, units="inches")
[1] 11.47222

Use it in a function and plot:

wrapTitle <- function(x, width=par("din")[1]){
  xx <- strwrap(x, width=0.8 * nchar(x) * width / strwidth(x, units="inches"))
  paste(xx, collapse="\n")
}

wrapTitle(title)
[1] "This is a really excessively wide title for a plot, especially since it\nprobably won't fit, meaning we somehow have to wrap it"

The plot:

ggplot(mtcars, aes(wt, mpg)) + geom_point() + opts(title=wrapTitle(title))

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If you want to save the plot to file, then you can replace par("din") with the actual saved plot dimensions.