R ggplot2 scale_colour_discrete 離散色階

默認離散色階。默認為scale_fill_hue() /scale_fill_brewer()，除非指定type(默認為ggplot2.discrete.fill /ggplot2.discrete.colour 選項)。

用法

scale_colour_discrete(..., type = getOption("ggplot2.discrete.colour"))

scale_fill_discrete(..., type = getOption("ggplot2.discrete.fill"))

參數

...

傳遞給比例類型的附加參數，

type

以下之一：

顏色代碼的字符向量。隻要代碼的數量超過數據級別的數量，代碼就用於'manual'色標(如果級別多於代碼，則使用scale_colour_hue()/scale_fill_hue()構建默認標度)。如果這是一個命名向量，則顏色值將根據向量名稱與級別進行匹配。不匹配的數據值將設置為 na.value 。
顏色代碼的字符向量列表。選擇超過數據級別數量的最小長度向量用於顏色縮放。如果您想根據級別數更改調色板，這非常有用。
返回離散顏色/填充比例的函數(例如 scale_fill_hue() 、 scale_fill_brewer() 等)。

例子

# Template function for creating densities grouped by a variable
cty_by_var <- function(var) {
  ggplot(mpg, aes(cty, colour = factor({{var}}), fill = factor({{var}}))) +
    geom_density(alpha = 0.2)
}

# The default, scale_fill_hue(), is not colour-blind safe
cty_by_var(class)


# (Temporarily) set the default to Okabe-Ito (which is colour-blind safe)
okabe <- c("#E69F00", "#56B4E9", "#009E73", "#F0E442", "#0072B2", "#D55E00", "#CC79A7")
withr::with_options(
  list(ggplot2.discrete.fill = okabe),
  print(cty_by_var(class))
)


# Define a collection of palettes to alter the default based on number of levels to encode
discrete_palettes <- list(
  c("skyblue", "orange"),
  RColorBrewer::brewer.pal(3, "Set2"),
  RColorBrewer::brewer.pal(6, "Accent")
)
withr::with_options(
  list(ggplot2.discrete.fill = discrete_palettes), {
  # 1st palette is used when there 1-2 levels (e.g., year)
  print(cty_by_var(year))
  # 2nd palette is used when there are 3 levels
  print(cty_by_var(drv))
  # 3rd palette is used when there are 4-6 levels
  print(cty_by_var(fl))
})


#> Warning: Groups with fewer than two data points have been dropped.
#> Warning: no non-missing arguments to max; returning -Inf

源代碼：R/scale-hue.R、R/zxx.R

相關用法

注：本文由純淨天空篩選整理自Hadley Wickham等大神的英文原創作品 Discrete colour scales。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。