devtools::load_all("~/packages/scales/")
#> ℹ Loading scales

# 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_lut(lut))
#> scale_x_discrete(labels = label_lut(lut))

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

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