Return the aesthetic mappings used by the ith layer

ith_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

ith_mappings(p, i, local_only = FALSE)

Arguments

p

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

i

A numerical index that corresponds to the first layer of a plot (1), the second layer (2), and so on. ith_mappings_use will check the aesthetics used by the ith layer.

local_only

If TRUE, ith_mappings_use will check only the mappings defined locally in a layer for the presence of mappings. If FALSE, ith_mappings_use will check for mappings in the combination of global and local methods that will be used to plot a layer.

Value

A list with class uneval, as returned by aes

Components of the list are either quosures or constants.

Details

Functions that use the ith_ prefix are designed to eliminate the need to call get_layer to check a specific layer in a plot, e.g. p %>% get_geom_layer(geom = "point") %>% get_mappings().

See also

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

Examples

require(ggplot2)
p <- ggplot(data = mpg, mapping = aes(x = displ, y = hwy)) +
  geom_point(mapping = aes(color = class)) +
  geom_smooth()
ith_mappings(p, i = 1, local_only = FALSE)
#> Aesthetic mapping: 
#> * `x`      -> `displ`
#> * `y`      -> `hwy`
#> * `colour` -> `class`
ith_mappings(p, i = 1, local_only = TRUE)
#> Aesthetic mapping: 
#> * `colour` -> `class`
ith_mappings(p, i = 2, local_only = FALSE)
#> Aesthetic mapping: 
#> * `x` -> `displ`
#> * `y` -> `hwy`