add_categorical_legend function

Add a categorical legend to a Mapbox GL map

This function adds a categorical legend to a Mapbox GL map. It supports customizable colors, sizes, and shapes for legend items.

add_categorical_legend(
  map,
  legend_title,
  values,
  colors,
  circular_patches = FALSE,
  position = "top-left",
  unique_id = NULL,
  sizes = NULL,
  add = FALSE,
  width = NULL,
  layer_id = NULL,
  margin_top = NULL,
  margin_right = NULL,
  margin_bottom = NULL,
  margin_left = NULL
)

Arguments

• map: A map object created by the mapboxgl function.
• legend_title: The title of the legend.
• values: A vector of categories or values to be displayed in the legend.
• colors: The corresponding colors for the values. Can be a vector of colors or a single color.
• circular_patches: Logical, whether to use circular patches in the legend. Default is FALSE.
• position: The position of the legend on the map. One of "top-left", "bottom-left", "top-right", "bottom-right". Default is "top-left".
• unique_id: A unique ID for the legend container. If NULL, a random ID will be generated.
• sizes: An optional numeric vector of sizes for the legend patches, or a single numeric value. If provided as a vector, it should have the same length as values. If circular_patches is FALSE (for square patches), sizes represent the width and height of the patch in pixels. If circular_patches is TRUE, sizes represent the radius of the circle.
• add: Logical, whether to add this legend to existing legends (TRUE) or replace existing legends (FALSE). Default is FALSE.
• width: The width of the legend. Can be specified in pixels (e.g., "250px") or as "auto". Default is NULL, which uses the built-in default.
• layer_id: The ID of the layer that this legend is associated with. If provided, the legend will be shown/hidden when the layer visibility is toggled.
• margin_top: Custom top margin in pixels, allowing for fine control over legend positioning. Default is NULL (uses standard positioning).
• margin_right: Custom right margin in pixels. Default is NULL.
• margin_bottom: Custom bottom margin in pixels. Default is NULL.
• margin_left: Custom left margin in pixels. Default is NULL.

Returns

The updated map object with the legend added.

Examples

## Not run:

library(mapboxgl)
map <- mapboxgl(
    center = c(-96, 37.8),
    zoom = 3
)
map %>% add_categorical_legend(
    legend_title = "Population",
    values = c("Low", "Medium", "High"),
    colors = c("#FED976", "#FEB24C", "#FD8D3C"),
    circular_patches = TRUE,
    sizes = c(10, 15, 20),
    width = "300px"
)
## End(Not run)