I would like to format a ggplot such that a geom_label is in the same vertical position in the panel regardless of the y limits, e.g. place the label 10% of the panel height from the panel bottom. Is there a straightforward way of doing this that doesn't involve creating a dataframe of label positions in advance?
1 Answers
Yes. You can use annotation_custom. Let's load ggplot2 and create some data first:
library(ggplot2)
set.seed(1)
df <- data.frame(x = 1:10, y = rnorm(10))
Now we will create a plot with a custom text annotation. The text annotation has to be a "textGrob", and we specify the units as "npc". In this case, we will draw some red text which is always at 90% of the plot's x axis and 90% of its y axis:
p <- ggplot(df, aes(x, y)) +
geom_point() +
annotation_custom(grid::textGrob(label = "my label",
x = unit(0.9, "npc"),
y = unit(0.9, "npc"),
gp = grid::gpar(col = "red")))
p
If we draw this again with different x (or y) limits, the label stays in the same place relative to the rest of the plot:
p + xlim(c(0, 50))
Created on 2020-09-15 by the reprex package (v0.3.0)
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