Based on gray.colors(). This is black and white equivalent of scale_colour_gradient().

scale_colour_grey(
...,
start = 0.2,
end = 0.8,
na.value = "red",
aesthetics = "colour"
)

scale_fill_grey(
...,
start = 0.2,
end = 0.8,
na.value = "red",
aesthetics = "fill"
)

## Arguments

... Arguments passed on to discrete_scale paletteA palette function that when called with a single integer argument (the number of levels in the scale) returns the values that they should take (e.g., scales::hue_pal()). breaksOne of: NULL for no breaks waiver() for the default breaks (the scale limits) A character vector of breaks A function that takes the limits as input and returns breaks as output limitsA character vector that defines possible values of the scale and their order. dropShould unused factor levels be omitted from the scale? The default, TRUE, uses the levels that appear in the data; FALSE uses all the levels in the factor. na.translateUnlike continuous scales, discrete scales can easily show missing values, and do so by default. If you want to remove missing values from a discrete scale, specify na.translate = FALSE. scale_nameThe name of the scale that should be used for error messages associated with this scale. nameThe 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. labelsOne of: NULL for no labels waiver() for the default labels computed by the transformation object A character vector giving labels (must be same length as breaks) A function that takes the breaks as input and returns labels as output expandFor position scales, a vector of range expansion constants used to add some padding around the data to ensure that they are placed some distance away from the axes. Use the convenience function expansion() to generate the values for the expand argument. The defaults are to expand the scale by 5% on each side for continuous variables, and by 0.6 units on each side for discrete variables. guideA function used to create a guide or its name. See guides() for more information. positionFor position scales, The position of the axis. left or right for y axes, top or bottom for x axes. superThe super class to use for the constructed scale grey value at low end of palette grey value at high end of palette Colour to use for missing values 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").

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

## Examples

p <- ggplot(mtcars, aes(mpg, wt)) + geom_point(aes(colour = factor(cyl)))
p + scale_colour_grey()p + scale_colour_grey(end = 0)
# You may want to turn off the pale grey background with this scale
p + scale_colour_grey() + theme_bw()
# Colour of missing values is controlled with na.value:
miss <- factor(sample(c(NA, 1:5), nrow(mtcars), replace = TRUE))
ggplot(mtcars, aes(mpg, wt)) +
geom_point(aes(colour = miss)) +
scale_colour_grey()ggplot(mtcars, aes(mpg, wt)) +
geom_point(aes(colour = miss)) +
scale_colour_grey(na.value = "green")