CODEWITHSUNDEEP
rggplot2
thothal
thothal

Reputation: 20399

Determine if a ggplot has a legend

Question

How would I find out programatically if any given ggplot object has a legend? I was thinking of transforming to a grob first and check whether there is a guide-box in the layout, but that feels a bit hackish. Any suggestions on how to do that in a reliable & reproducible way?

Code

library(ggplot2)
library(grid)
bp <- ggplot(iris, aes(Petal.Length, Petal.Width)) + theme(legend.position = "top")
noLegend <- bp + geom_point()
withLegend <- bp + geom_point(aes(color = Species))
gNoLegend <- ggplotGrob(noLegend)
gWithLegend <- ggplotGrob(withLegend)

any(gNoLegend$layout$name == "guide-box")
# [1] FALSE
any(gWithLegend$layout$name == "guide-box")
# [1] TRUE

Upvotes: 3

Views: 171

Answers (1)

Axeman
Axeman

Reputation: 35382

A simple function (although I think your method is fine too):

check_for_legend <- function(x) {
  'gtable' %in% class(try(cowplot::get_legend(x), silent = TRUE))
}
check_for_legend(noLegend)

FALSE

check_for_legend(withLegend)

TRUE

Upvotes: 5

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