Create a ggplot2 annotation given some aesthetics, parameters, and facet variables + values.

This function is based on ggplot2::annotate(). The two main differences are: it returns an unevaluated function call rather than a ggproto object; and it can handle limiting annotations to (specified) facet level(s).

Usage

make_layer(geom, aes = NULL, params = NULL, facets = NULL)

Arguments

geom: Geom to annotate, such as "text".
aes: Named list of aesthetics with corresponding data values, as in `list(x = 3, y = 30, label = "A label")`.
params: Optional. Named list of parameters for geom, such as `list(colour = "black")`
facets: Optional. Named list of facets; the name is the variable and the value if the level, such as `list(cyl = 4)`.

Value

A call

Examples

library(ggplot2)

base_plot <- ggplot(mtcars, aes(x = wt, y = mpg)) +
  geom_point() +
  facet_wrap(~cyl)

my_annot_call <- make_layer("text",
  aes = list(x = 3, y = 30, label = "A label"),
  facets = list(cyl = 6),
  params = list(col = "red")
)

my_annotation <- eval(my_annot_call)

base_plot + my_annotation