Discrete scale constructor.

discrete_scale(aesthetics, scale_name, palette, name = waiver(),
breaks = waiver(), labels = waiver(), limits = NULL,
expand = waiver(), na.translate = TRUE, na.value = NA,
drop = TRUE, guide = "legend", position = "left",
super = ScaleDiscrete)

## Arguments

aesthetics The names of the aesthetics that this scale works with The name of the scale A palette function that when called with a single integer argument (the number of levels in the scale) returns the values that they should take. 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. One of: NULL for no breaks waiver() for the default breaks computed by the transformation object A character vector of breaks A function that takes the limits as input and returns breaks as output One 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 A character vector that defines possible values of the scale and their order. 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 expand_scale() 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. Unlike 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. If na.translate = TRUE, what value aesthetic value should missing be displayed as? Does not apply to position scales where NA is always placed at the far right. Should 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. A function used to create a guide or its name. See guides() for more info. The position of the axis. "left" or "right" for vertical scales, "top" or "bottom" for horizontal scales The super class to use for the constructed scale