R/new-scale.R

In ggnewscale: Multiple Fill and Colour Scales in 'ggplot2'

#' Adds a new scale to a plot
#'
#' Creates a new scale "slot". Geoms added to a plot after this function will
#' use a new scale definition.
#'
#' @param new_aes A string with the name of the aesthetic for which a new scale
#' will be created.
#'
#' @details
#' `new_scale_color()`, `new_scale_colour()` and `new_scale_fill()` are just
#' aliases to `new_scale("color")`, etc...
#'
#' @examples
#' library(ggplot2)
#'
#' # Equivalent to melt(volcano), but we don't want to depend on reshape2
#' topography <- expand.grid(x = 1:nrow(volcano),
#'                           y = 1:ncol(volcano))
#' topography$z <- c(volcano)
#'
#' # point measurements of something at a few locations
#' measurements <- data.frame(x = runif(30, 1, 80),
#'                            y = runif(30, 1, 60),
#'                            thing = rnorm(30))
#'
#' ggplot(mapping = aes(x, y)) +
#'   geom_contour(data = topography, aes(z = z, color = stat(level))) +
#'   # Color scale for topography
#'   scale_color_viridis_c(option = "D") +
#'   # geoms below will use another color scale
#'   new_scale_color() +
#'   geom_point(data = measurements, size = 3, aes(color = thing)) +
#'   # Color scale applied to geoms added after new_scale_color()
#'   scale_color_viridis_c(option = "A")
#'
#' @export
new_scale <- function(new_aes) {
  structure(ggplot2::standardise_aes_names(new_aes), class = "new_aes")
}

#' @export
#' @rdname new_scale
new_scale_fill <- function() {
  new_scale("fill")
}

#' @export
#' @rdname new_scale
new_scale_color <- function() {
  new_scale("colour")
}

#' @export
#' @rdname new_scale
new_scale_colour <- function() {
  new_scale("colour")
}