Get aesthetic mappings from a layer or plot

get_mappings returns the mappings used by a ggplot object or a single layer extracted from the object with get_geom_layer or get_stat_layer.

Usage

get_mappings(p, local_only = FALSE)

Arguments

p

A ggplot object or a layer extracted from a ggplot object with get_geom_layer or get_stat_layer.

local_only

TRUE or FALSE. Should get_mappings return only the mappings defined locally in a layer. This has no effect when p is a ggplot object.

Value

A list with class uneval, as returned by aes

Components of the list are either quosures or constants.

Details

When passed a ggplot object (i.e. a plot), get_mappings will return only the mappings that have been set globally with ggplot. When passed a single layer from a plot, the behavior of get_mappings will depend on the value of local_only. If local_only = TRUE, get_mappings will return only the mappings defined locally in a layer. When local_only = FALSE, get_mappings will return the combination of global and local methods that will be used to plot a layer.

See also

Other functions for checking mappings: identical_aes(), ith_mappings_use(), ith_mappings(), uses_mappings()

Examples

require(ggplot2)
p <- ggplot(data = mpg, mapping = aes(x = displ, y = hwy)) +
  geom_point(mapping = aes(color = class))
get_mappings(p)
#> Aesthetic mapping: 
#> * `x`      -> `displ`
#> * `y`      -> `hwy`
#> * `colour` -> `class`
get_mappings(get_geom_layer(p, i = 1), local_only = FALSE)
#> Aesthetic mapping: 
#> * `x`      -> `displ`
#> * `y`      -> `hwy`
#> * `colour` -> `class`