Return a random colour gradient — "I'm Feeling Lucky" for palettes

Picks one of the 7140 colour gradients at random and returns it, optionally printing its name so you can re-use it later. Based on Google's "I'm Feeling Lucky" button.

lucky(
  n = 100,
  colorRampPalette = FALSE,
  rev = FALSE,
  message = TRUE,
  nseed,
  frgb = rep(1, 3)
)

Arguments

n

Integer. Number of colours to return when colorRampPalette = FALSE. Ignored when colorRampPalette = TRUE.

colorRampPalette

Logical. If FALSE (default), returns a character vector of n colours. If TRUE, returns a colorRampPalette function — the right choice for plot and ggplot2.

rev

Logical. If TRUE, reverse the gradient order.

message

Logical. If TRUE (default), prints the name and index of the chosen palette to the console.

nseed

Integer. A seed value passed to set.seed for reproducible random selection.

frgb

Numeric vector of length 3. Per-channel scaling factors for c(red, green, blue). Default c(1, 1, 1).

Value

A character vector of hex colours when colorRampPalette = FALSE, or a colorRampPalette function when colorRampPalette = TRUE.

Examples

library(cptcity)

# Random palette each time you call it
image(matrix(1:100), col = lucky())
#> Colour gradient: cmocean_gray, number: 577

image(matrix(1:100), col = lucky())
#> Colour gradient: nd_vermillion_Analogous_08, number: 5957

image(matrix(1:100), col = lucky(rev = TRUE))
#> Colour gradient: jjg_polarity_PiYG, number: 4289


# Reproducible random pick
image(matrix(1:100), col = lucky(nseed = 42))
#> Colour gradient: pj_1_fe2, number: 6532

image(matrix(1:100), col = lucky(nseed = 42))  # same palette
#> Colour gradient: pj_1_fe2, number: 6532

# Silent mode + sf-compatible output
if (FALSE) { # \dontrun{
library(sf)
nc <- st_read(system.file("shape/nc.shp", package = "sf"))
plot(nc["AREA"], pal = lucky(colorRampPalette = TRUE, message = FALSE))
} # }