ggplot query or change plot limits

Question

I have a ggplot object returned by a function in an R package. I want to add some elements to this plot before plotting it. But, I do not know the plot limits. Is there a way to query the ggplot object to find the plot limits? Actually, what I'd really like to do is simply set new limits for subsequent plotting, but I understand this is not possible, based on discussions of the impossibility of plotting data against two different y-axes.

For example, say I want to plot a small rectangle in lower-left corner of plot, but not knowing the plot limits, I don't know where to put it:

p = function() return(ggplot() + xlim(-2, 5) + ylim(-3, 5) +
    geom_rect(mapping=aes(xmin=1, xmax=2, ymin=1, ymax=2)))
gp = p()
gp = gp + geom_rect(mapping=aes(xmin=0, ymin=0, xmax=0.5, ymax=0.5))
print(gp)

score 1 · Answer 1 · answered Nov 20 '18 at 22:45

1

In ggplot2 3.0.0:
ggplot_build(gp)$layout$panel_params[[1]][c("x.range","y.range")]

answered Nov 20 '18 at 22:45

user9075228

11
4

score 0 · Answer 2 · answered Oct 14 '16 at 20:49

0

ggplot_build(p)$layout$panel_ranges[[1]][c("x.range","y.range")]

answered Oct 14 '16 at 20:49

baptiste

75,767
19
198
294

Thanks. That didn't work but led me to the following, which does: ggplot_build(gp)$panel$ranges[[1]][c("x.range","y.range")] – tedtoal Oct 16 '16 at 20:03
probably different ggplot2 versions, feel free to edit – baptiste Oct 16 '16 at 20:54

ggplot query or change plot limits

2 Answers2