Labels from lookup tables

Use label_dictionary() for looking up succinct breaks in a named character vector giving complete labels.

Usage

label_dictionary(dictionary = character(), nomatch = NULL)

Arguments

dictionary

A named character vector of labels. The names are expected to match the breaks, and the values become the labels.

nomatch

A string to label breaks that do not match any name in dictionary. When NULL (default), the breaks are not translated but are kept as-is.

Value

All label_() functions return a "labelling" function, i.e. a function that takes a vector x and returns a character vector of length(x) giving a label for each input value.

Labelling functions are designed to be used with the labels argument of ggplot2 scales. The examples demonstrate their use with x scales, but they work similarly for all scales, including those that generate legends rather than axes.

See also

Other labels for discrete scales: label_glue(), label_parse(), label_wrap()

Examples

# Example lookup table
lut <- c(
  "4" = "four wheel drive",
  "r" = "rear wheel drive",
  "f" = "front wheel drive"
)

# Typical usage
demo_discrete(c("4", "r", "f"), labels = label_dictionary(lut))
#> scale_x_discrete(labels = label_dictionary(lut))

# By default, extra values ('w') will remain as-is
demo_discrete(c("4", "r", "f", "w"), labels = label_dictionary(lut))
#> scale_x_discrete(labels = label_dictionary(lut))

# Alternatively, you can relabel extra values
demo_discrete(
  c("4", "r", "f", "w"),
  labels = label_dictionary(lut, nomatch = "unknown")
)
#> scale_x_discrete(labels = label_dictionary(lut, nomatch = "unknown"))