scale_identity: Use values without scaling

In ggplot2: Create Elegant Data Visualisations Using the Grammar of Graphics

Use values without scaling

Description

Use this set of scales when your data has already been scaled, i.e. it already represents aesthetic values that ggplot2 can handle directly. These scales will not produce a legend unless you also supply the breaks, labels, and type of guide you want.

Usage

scale_colour_identity(
  name = waiver(),
  ...,
  guide = "none",
  aesthetics = "colour"
)

scale_fill_identity(name = waiver(), ..., guide = "none", aesthetics = "fill")

scale_shape_identity(
  name = waiver(),
  ...,
  guide = "none",
  aesthetics = "shape"
)

scale_linetype_identity(
  name = waiver(),
  ...,
  guide = "none",
  aesthetics = "linetype"
)

scale_linewidth_identity(
  name = waiver(),
  ...,
  guide = "none",
  aesthetics = "linewidth"
)

scale_alpha_identity(
  name = waiver(),
  ...,
  guide = "none",
  aesthetics = "alpha"
)

scale_size_identity(name = waiver(), ..., guide = "none", aesthetics = "size")

scale_discrete_identity(aesthetics, name = waiver(), ..., guide = "none")

scale_continuous_identity(aesthetics, name = waiver(), ..., guide = "none")

Arguments

name	The name of the scale. Used as the axis or legend title. If waiver(), the default, the name of the scale is taken from the first mapping used for that aesthetic. If NULL, the legend title will be omitted.
...	Other arguments passed on to discrete_scale() or continuous_scale()
guide	Guide to use for this scale. Defaults to "none".
aesthetics	Character string or vector of character strings listing the name(s) of the aesthetic(s) that this scale works with. This can be useful, for example, to apply colour settings to the colour and fill aesthetics at the same time, via aesthetics = c("colour", "fill").

Details

The functions scale_colour_identity(), scale_fill_identity(), scale_size_identity(), etc. work on the aesthetics specified in the scale name: colour, fill, size, etc. However, the functions scale_colour_identity() and scale_fill_identity() also have an optional aesthetics argument that can be used to define both colour and fill aesthetic mappings via a single function call. The functions scale_discrete_identity() and scale_continuous_identity() are generic scales that can work with any aesthetic or set of aesthetics provided via the aesthetics argument.

See Also

The identity scales section of the online ggplot2 book.

Other shape scales: scale_shape(), scale_shape_manual().

Other linetype scales: scale_linetype(), scale_linetype_manual().

Other alpha scales: scale_alpha(), scale_alpha_manual().

Other size scales: scale_size(), scale_size_manual().

Other colour scales: scale_alpha(), scale_colour_brewer(), scale_colour_continuous(), scale_colour_gradient(), scale_colour_grey(), scale_colour_hue(), scale_colour_manual(), scale_colour_steps(), scale_colour_viridis_d()

Examples

ggplot(luv_colours, aes(u, v)) +
  geom_point(aes(colour = col), size = 3) +
  scale_color_identity() +
  coord_fixed()

df <- data.frame(
  x = 1:4,
  y = 1:4,
  colour = c("red", "green", "blue", "yellow")
)
ggplot(df, aes(x, y)) + geom_tile(aes(fill = colour))
ggplot(df, aes(x, y)) +
  geom_tile(aes(fill = colour)) +
  scale_fill_identity()

# To get a legend guide, specify guide = "legend"
ggplot(df, aes(x, y)) +
  geom_tile(aes(fill = colour)) +
  scale_fill_identity(guide = "legend")
# But you'll typically also need to supply breaks and labels:
ggplot(df, aes(x, y)) +
  geom_tile(aes(fill = colour)) +
  scale_fill_identity("trt", labels = letters[1:4], breaks = df$colour,
  guide = "legend")

# cyl scaled to appropriate size
ggplot(mtcars, aes(mpg, wt)) +
  geom_point(aes(size = cyl))

# cyl used as point size
ggplot(mtcars, aes(mpg, wt)) +
  geom_point(aes(size = cyl)) +
  scale_size_identity()

ggplot2 documentation built on Sept. 11, 2025, 9:10 a.m.