R ggplot2 scale_gradient 漸變色階

scale_colour_gradient(
  ...,
  low = "#132B43",
  high = "#56B1F7",
  space = "Lab",
  na.value = "grey50",
  guide = "colourbar",
  aesthetics = "colour"
)

scale_fill_gradient(
  ...,
  low = "#132B43",
  high = "#56B1F7",
  space = "Lab",
  na.value = "grey50",
  guide = "colourbar",
  aesthetics = "fill"
)

scale_colour_gradient2(
  ...,
  low = muted("red"),
  mid = "white",
  high = muted("blue"),
  midpoint = 0,
  space = "Lab",
  na.value = "grey50",
  guide = "colourbar",
  aesthetics = "colour"
)

scale_fill_gradient2(
  ...,
  low = muted("red"),
  mid = "white",
  high = muted("blue"),
  midpoint = 0,
  space = "Lab",
  na.value = "grey50",
  guide = "colourbar",
  aesthetics = "fill"
)

scale_colour_gradientn(
  ...,
  colours,
  values = NULL,
  space = "Lab",
  na.value = "grey50",
  guide = "colourbar",
  aesthetics = "colour",
  colors
)

scale_fill_gradientn(
  ...,
  colours,
  values = NULL,
  space = "Lab",
  na.value = "grey50",
  guide = "colourbar",
  aesthetics = "fill",
  colors
)

scales::seq_gradient_pal() 了解底層調色板的詳細信息，scale_colour_steps() 了解這些比例的分級變體。

其他色標：scale_alpha()、scale_colour_brewer()、scale_colour_continuous()、scale_colour_grey()、scale_colour_hue()、scale_colour_steps()、scale_colour_viridis_d()

set.seed(1)
df <- data.frame(
  x = runif(100),
  y = runif(100),
  z1 = rnorm(100),
  z2 = abs(rnorm(100))
)

df_na <- data.frame(
  value = seq(1, 20),
  x = runif(20),
  y = runif(20),
  z1 = c(rep(NA, 10), rnorm(10))
)

# Default colour scale colours from light blue to dark blue
ggplot(df, aes(x, y)) +
  geom_point(aes(colour = z2))


# For diverging colour scales use gradient2
ggplot(df, aes(x, y)) +
  geom_point(aes(colour = z1)) +
  scale_colour_gradient2()


# Use your own colour scale with gradientn
ggplot(df, aes(x, y)) +
  geom_point(aes(colour = z1)) +
  scale_colour_gradientn(colours = terrain.colors(10))


# Equivalent fill scales do the same job for the fill aesthetic
ggplot(faithfuld, aes(waiting, eruptions)) +
  geom_raster(aes(fill = density)) +
  scale_fill_gradientn(colours = terrain.colors(10))


# Adjust colour choices with low and high
ggplot(df, aes(x, y)) +
  geom_point(aes(colour = z2)) +
  scale_colour_gradient(low = "white", high = "black")

# Avoid red-green colour contrasts because ~10% of men have difficulty
# seeing them

# Use `na.value = NA` to hide missing values but keep the original axis range
ggplot(df_na, aes(x = value, y)) +
  geom_bar(aes(fill = z1), stat = "identity") +
  scale_fill_gradient(low = "yellow", high = "red", na.value = NA)


 ggplot(df_na, aes(x, y)) +
   geom_point(aes(colour = z1)) +
   scale_colour_gradient(low = "yellow", high = "red", na.value = NA)
#> Warning: Removed 10 rows containing missing values (`geom_point()`).