Points don't inherit font family

[botanize]

I expect that the font-family specified in the theme is applied to all applicable graphical content. However, when specifying some unicode characters for the shape scale I get empty boxes instead of the characters. Point geometries can use arbitrary characters for the shape scale, but not all characters are available in all font families. While constructing the points grob, GeomPoint omits the fontfamily gpar parameter, which means that there is no way to specify a font family that contains the desired characters. The standard ways of specifying a font family for the quartz device don't work for the gpar fontfamily (quartz(family =, or quartzFonts(sans = quartzFont(…).

library(ggplot2)
library(grid)

theme_set(theme_minimal(base_family = 'Apple SD Gothic Neo'))

p = ggplot(data.frame(x = 1:3, y = 1:3, shape = factor(0:2)), aes(x, y)) + geom_point(aes(shape = shape), size = 4) + scale_shape_manual(values = c('0' = '\u2013', '1' = '◀', '2' = '\u25B6')) + theme(text = element_text(family = 'Apple SD Gothic Neo'))
print(p)
data = ggplot_build(p)
gtable = ggplot_gtable(data)
grid.draw(gtable)

# add family to gpar for points grob
gtable$grobs[[6]]$children[[3]]$gp$fontfamily = 'Apple SD Gothic Neo'
grid.newpage()
grid.draw(gtable)

^{Created on 2020-12-29 by the reprex package (v0.3.0)}

I get the behavior I want by adding the font family gpar parameter to the correct grobs as above or to the gtable itself:

data = ggplot_build(p)
gtable = ggplot_gtable(data)
gtable$gp = gpar(fontfamily = 'Apple SD Gothic Neo')
grid.draw(gtable)

From a user perspective, I think this could be fixed by either adding a family parameter to scale_shape or inheriting the family from the theme or device.

[thomasp85]

I agree about your request for this functionality - in the meantime you can use the ragg devices to avoid the boxes as it should be able to figure out a fallback font

[teunbrand]

The layers currently don't know about the theme. Wouldn't it be simpler to add a font argument to geom_point()?

[teunbrand]

After some consideration, I've come to argue that we shouldn't fix this.
The reason is that geom_point() is/should be for shapes 0-25, not for text.
To quote Hiroaki:

I think ggplot2 should have prohibited any use of these single characters as a shape. We can use arbitrary letter here, but I feel this isn't a "point" geom anymore.

The correct solution is to use a text geom, with a label scale. If the argument is 'but then we cannot use the shape symbols', you'd be right, but there are plenty of unicode shapes that capture all types of symbols you can use. As a last resort, you can divide the data over a point/text layer.

Unfortunately, manual_scale() is not exported, but that is a matter for a different issue. We can easily redirect e.g. scale_colour_manual() instead.

library(ggplot2)

data.frame(x = 1:3, y = 1:3, shape = factor(0:2)) |>
  ggplot(aes(x, y)) + 
  geom_text(aes(label = shape), size = 4, family = "Montserrat") +
  scale_colour_manual(
    values = c('0' = '\u2013', '1' = '◀', '2' = '\u25B6'), 
    aesthetics = "label"
  )

^{Created on 2025-02-24 with reprex v2.1.1}

I'm going to close this for now, but we can reopen if new compelling arguments resurface.