Generate discrete color values for numerous categories (>10)

all_the_colors.R

library(ggplot2)

# Make a vector of colors of size n based on an RColorBrewer palette
# or list of colors.
get_extended_palette = function(original_palette = 'Paired', n){
  brewer_palettes = rownames(RColorBrewer::brewer.pal.info)
  if(length(original_palette)>=2){
    original_palette_values = original_palette
  } else if(original_palette %in% brewer_palettes){
      original_palette_values = RColorBrewer::brewer.pal(9, original_palette) # most of the palettes have 9 colors to start with
  } else {
    stop('Unknown palette name')
  }
  generate_palette = colorRampPalette(original_palette_values)
  generate_palette(n)
}

color_count = 20
# Pass in a brewer palette which serves as a base for colors generated. 
palette = sample(get_extended_palette(original_palette = 'Set1',n=color_count))

tibble(x=1:color_count) %>%
  ggplot() +
  geom_vline(aes(xintercept = x, color=as.factor(x)), size=5) +
  scale_color_manual(values = palette) +
  theme(legend.position = 'none')

# Or pass in a list of colors to start with instead. 
palette = sample(get_extended_palette(original_palette = c('gold','black','green4','violetred'),n=color_count))

tibble(x=1:color_count) %>%
  ggplot() +
  geom_vline(aes(xintercept = x, color=as.factor(x)), size=5) +
  scale_color_manual(values = palette) +
  theme(legend.position = 'none')