strip.text angle doesn't work when `facet_wrap` position is "left" or "right"

[rwilson8]

I found a problem with the angle of strip text when using facet_wrap().

I expected the angle of the strip text to rotate according to the angle argument of the element_text() function in the theme function. The text only rotates when strip.position is "top" or "bottom," not "left" or "right."

Here is the code to reproduce the bug:

library(ggplot2)

p <- ggplot(iris, aes(Sepal.Length, Sepal.Width)) +
  geom_point() +
  theme(strip.text = element_text(angle = 45))

p + facet_wrap(~Species, strip.position = "top")

p + facet_wrap(~Species, strip.position = "left")

p + facet_wrap(~Species, strip.position = "right")

p + facet_wrap(~Species, strip.position = "bottom")

[teunbrand]

Thanks for the report! This is due to how theme inheritance works. The 'base' strip text is horizontal by default. In your code, you're setting the angle of this base strip text. Because top/bottom strip text doesn't need to deviate from the base strip text, they inherit the angle directly. In contrast, the left and right strip text is displayed vertically, meaning they already have an angle that override the base text angle. To change these, you'd need to set strip.text.y.left and strip.text.y.right theme elements. This is not a bug, but exactly how theme inheritance works.

[rwilson8]

Thank you for your response and for the clarification.