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#' Sequential, diverging and qualitative colour scales from colorbrewer.org
#'
#' ColorBrewer provides sequential, diverging and qualitative colour schemes
#' which are particularly suited and tested to display discrete values (levels
#' of a factor) on a map. ggplot2 can use those colours in discrete scales. It
#' also allows to smoothly interpolate 6 colours from any palette to a
#' continuous scale (6 colours per palette gives nice gradients; more results in
#' more saturated colours which do not look as good). However, the original
#' colour schemes (particularly the qualitative ones) were not intended for this
#' and the perceptual result is left to the appreciation of the user.
#'
#' See \url{http://colorbrewer2.org} for more information.
#'
#' @inheritParams scales::brewer_pal
#' @inheritParams scale_colour_hue
#' @inheritParams scale_colour_gradient
#' @inheritParams scales::gradient_n_pal
#' @family colour scales
#' @rdname scale_brewer
#' @export
#' @examples
#' dsamp <- diamonds[sample(nrow(diamonds), 1000), ]
#' (d <- qplot(carat, price, data = dsamp, colour = clarity))
#'
#' # Change scale label
#' d + scale_colour_brewer()
#' d + scale_colour_brewer("clarity")
#' d + scale_colour_brewer(expression(clarity[beta]))
#'
#' # Select brewer palette to use, see ?scales::brewer_pal for more details
#' d + scale_colour_brewer(type = "seq")
#' d + scale_colour_brewer(type = "seq", palette = 3)
#'
#' d + scale_colour_brewer(palette = "Blues")
#' d + scale_colour_brewer(palette = "Set1")
#'
#' # scale_fill_brewer works just the same as
#' # scale_colour_brewer but for fill colours
#' ggplot(diamonds, aes(x = price, fill = cut)) +
#' geom_histogram(position = "dodge", binwidth = 1000) +
#' scale_fill_brewer()
#'
#' # Generate map data
#' library(reshape2) # for melt
#' volcano3d <- melt(volcano)
#' names(volcano3d) <- c("x", "y", "z")
#'
#' # Basic plot
#' v <- ggplot() + geom_tile(aes(x = x, y = y, fill = z), data = volcano3d)
#' v
#' v + scale_fill_distiller()
#' v + scale_fill_distiller(palette = 2)
#' v + scale_fill_distiller(type = "div")
#' v + scale_fill_distiller(palette = "Spectral")
#' v + scale_fill_distiller(palette = "Spectral", trans = "reverse")
#' v + scale_fill_distiller(type = "qual")
#' # Not appropriate for continuous data, issues a warning
scale_colour_brewer <- function(..., type = "seq", palette = 1) {
discrete_scale("colour", "brewer", brewer_pal(type, palette), ...)
}
#' @export
#' @rdname scale_brewer
scale_fill_brewer <- function(..., type = "seq", palette = 1) {
discrete_scale("fill", "brewer", brewer_pal(type, palette), ...)
}
#' @export
#' @rdname scale_brewer
scale_colour_distiller <- function(..., type = "seq", palette = 1, values = NULL, space = "Lab", na.value = "grey50") {
# warn about using a qualitative brewer palette to generate the gradient
type <- match.arg(type, c("seq", "div", "qual"))
if (type == "qual") {
warning("Using a discrete colour palette in a continuous scale.\n Consider using type = \"seq\" or type = \"div\" instead", call. = FALSE)
}
continuous_scale("colour", "distiller",
gradient_n_pal(brewer_pal(type, palette)(6), values, space), na.value = na.value, ...)
# NB: 6 colours per palette gives nice gradients; more results in more saturated colours which do not look as good
}
#' @export
#' @rdname scale_brewer
scale_fill_distiller <- function(..., type = "seq", palette = 1, values = NULL, space = "Lab", na.value = "grey50") {
type <- match.arg(type, c("seq", "div", "qual"))
if (type == "qual") {
warning("Using a discrete colour palette in a continuous scale.\n Consider using type = \"seq\" or type = \"div\" instead", call. = FALSE)
}
continuous_scale("fill", "distiller",
gradient_n_pal(brewer_pal(type, palette)(6), values, space), na.value = na.value, ...)
}
# icon.brewer <- function() {
# rectGrob(c(0.1, 0.3, 0.5, 0.7, 0.9), width = 0.21,
# gp = gpar(fill = RColorBrewer::brewer.pal(5, "PuOr"), col = NA)
# )
# }
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