R function to generate 2D Density colors for ggplot

density_color_function.R

## Density color function
# usage:
# tbl |> 
#     mutate(density = getDenCols(x, y, transform = TRUE)) |> # transformation here must match aes()
#     arrange(density) |> # ensures highest desity points on top
#     ggplot(aes(log2(x), log2(y), color = density)) +
#     geom_point() +
#     scale_color_vididis_c() # works best with viridis
getDenCols <- function(x, y, transform = TRUE) { # set to TRUE if using log2 transformation of data
  if(transform) {
    df <- data.frame(log2(x), log2(y))
  } else{
    df <- data.frame(x, y)
  }
  z <- grDevices::densCols(df, colramp = grDevices::colorRampPalette(c("black", "white")))
  df$dens <- grDevices::col2rgb(z)[1,] + 1L
  cols <-  grDevices::colorRampPalette(c("#000099", "#00FEFF", "#45FE4F","#FCFF00", "#FF9400", "#FF3100"))(256)
  df$col <- cols[df$dens]
  return(df$dens)
} # End of function