mapgl (version 0.4.3)

palette_to_lut: Convert R color palette to mapgl LUT

Description

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
)

Value

Base64-encoded PNG data URI string

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) {
# 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
    )
  )
)
}