Legend key glyph: an icon

A ggplot2::draw_key() function that draws the icon itself as the legend key glyph, instead of a generic point/rect. This is geom_icon()'s default key_glyph; set key_glyph = draw_key_icon on another geom to borrow it.

Usage

draw_key_icon(data, params, size)

Arguments

data

A single row data frame containing the scaled aesthetics to display in this key

params

A list of additional parameters supplied to the geom.

size

Width and height of key in mm.

Value

A grob.

Examples

library(ggplot2)

# bundled placeholder shapes; a real pack (e.g. icons::fontawesome) works the same
shapes <- icons::icon_set(system.file("icons", package = "ggicons"))

# borrowed onto geom_point() so its legend key shows the mapped icon
df <- data.frame(x = 1:3, y = c(1, 3, 2), cat = c("a", "b", "c"))
ggplot(df, aes(x, y, colour = cat, icon = cat)) +
  geom_point(size = 10, key_glyph = draw_key_icon) +
  scale_icon_manual(values = c(shapes$square, shapes$circle, shapes$triangle))