R ggplot2 scale_colour_discrete 离散色阶

默认离散色阶。默认为scale_fill_hue() /scale_fill_brewer()，除非指定type(默认为ggplot2.discrete.fill /ggplot2.discrete.colour 选项)。

用法

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

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

参数

...

传递给比例类型的附加参数，

type

以下之一：

颜色代码的字符向量。只要代码的数量超过数据级别的数量，代码就用于'manual'色标(如果级别多于代码，则使用scale_colour_hue()/scale_fill_hue()构建默认标度)。如果这是一个命名向量，则颜色值将根据向量名称与级别进行匹配。不匹配的数据值将设置为 na.value 。
颜色代码的字符向量列表。选择超过数据级别数量的最小长度向量用于颜色缩放。如果您想根据级别数更改调色板，这非常有用。
返回离散颜色/填充比例的函数(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

源代码：R/scale-hue.R、R/zxx.R

相关用法

注：本文由纯净天空筛选整理自Hadley Wickham等大神的英文原创作品 Discrete colour scales。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。