This function takes an R color palette and converts it into a base64-encoded LUT (Look-Up Table) image that can be used with Mapbox GL JS v3+ for custom map themes. The LUT applies color transformations to the basemap.
Usage
palette_to_lut(
colors,
n = 5,
method = c("tint", "replace", "duotone", "tritone", "luminosity"),
intensity = 0.5,
lut_size = 32,
reverse = FALSE
)Arguments
- colors
Character vector of colors (hex or R color names) or a function that generates colors (like viridis)
- n
Number of colors to sample from the palette (if colors is a function)
- method
Method for applying colors to the LUT:
"tint": Applies palette as a color tint/overlay"replace": Maps grayscale values to palette colors"duotone": Creates duotone effect with first two colors"tritone": Creates tritone effect with first three colors"luminosity": Applies palette based on pixel luminosity
- intensity
Strength of the effect (0-1)
- lut_size
Size of the LUT (16, 32, or 64)
- reverse
Logical; whether to reverse the color palette
Examples
if (FALSE) { # \dontrun{
# Using viridis palette
theme_data <- palette_to_lut(viridisLite::viridis(5))
# Using a palette function directly
theme_data <- palette_to_lut(viridisLite::plasma, n = 7)
# Using RColorBrewer
theme_data <- palette_to_lut(RColorBrewer::brewer.pal(9, "YlOrRd"))
# Use in mapboxgl (requires Mapbox GL JS v3+)
mapboxgl(
center = c(139.7, 35.7),
zoom = 10,
config = list(
basemap = list(
theme = "custom",
"theme-data" = theme_data
)
)
)
} # }