add_circle_layer function

Add a circle layer to a Mapbox GL map

add_circle_layer(
  map,
  id,
  source,
  source_layer = NULL,
  circle_blur = NULL,
  circle_color = NULL,
  circle_opacity = NULL,
  circle_radius = NULL,
  circle_sort_key = NULL,
  circle_stroke_color = NULL,
  circle_stroke_opacity = NULL,
  circle_stroke_width = NULL,
  circle_translate = NULL,
  circle_translate_anchor = "map",
  visibility = "visible",
  slot = NULL,
  min_zoom = NULL,
  max_zoom = NULL,
  popup = NULL,
  tooltip = NULL,
  hover_options = NULL,
  before_id = NULL,
  filter = NULL,
  cluster_options = NULL
)

Arguments

• map: A map object created by the mapboxgl function.
• id: A unique ID for the layer.
• source: The ID of the source, alternatively an sf object (which will be converted to a GeoJSON source) or a named list that specifies type and url for a remote source.
• source_layer: The source layer (for vector sources).
• circle_blur: Amount to blur the circle.
• circle_color: The color of the circle.
• circle_opacity: The opacity at which the circle will be drawn.
• circle_radius: Circle radius.
• circle_sort_key: Sorts features in ascending order based on this value.
• circle_stroke_color: The color of the circle's stroke.
• circle_stroke_opacity: The opacity of the circle's stroke.
• circle_stroke_width: The width of the circle's stroke.
• circle_translate: The geometry's offset. Values are c(x, y) where negatives indicate left and up.
• circle_translate_anchor: Controls the frame of reference for circle-translate.
• visibility: Whether this layer is displayed.
• slot: An optional slot for layer order.
• min_zoom: The minimum zoom level for the layer.
• max_zoom: The maximum zoom level for the layer.
• popup: A column name containing information to display in a popup on click. Columns containing HTML will be parsed.
• tooltip: A column name containing information to display in a tooltip on hover. Columns containing HTML will be parsed.
• hover_options: A named list of options for highlighting features in the layer on hover.
• before_id: The name of the layer that this layer appears "before", allowing you to insert layers below other layers in your basemap (e.g. labels).
• filter: An optional filter expression to subset features in the layer.
• cluster_options: A list of options for clustering circles, created by the cluster_options() function.

Returns

The modified map object with the new circle layer added.

Examples

## Not run:

library(mapgl)
library(sf)
library(dplyr)

# Set seed for reproducibility
set.seed(1234)

# Define the bounding box for Washington DC (approximately)
bbox <- st_bbox(
    c(
        xmin = -77.119759,
        ymin = 38.791645,
        xmax = -76.909393,
        ymax = 38.995548
    ),
    crs = st_crs(4326)
)

# Generate 30 random points within the bounding box
random_points <- st_as_sf(
    data.frame(
        id = 1:30,
        lon = runif(30, bbox["xmin"], bbox["xmax"]),
        lat = runif(30, bbox["ymin"], bbox["ymax"])
    ),
    coords = c("lon", "lat"),
    crs = 4326
)

# Assign random categories
categories <- c("music", "bar", "theatre", "bicycle")
random_points <- random_points %>%
    mutate(category = sample(categories, n(), replace = TRUE))

# Map with circle layer
mapboxgl(style = mapbox_style("light")) %>%
    fit_bounds(random_points, animate = FALSE) %>%
    add_circle_layer(
        id = "poi-layer",
        source = random_points,
        circle_color = match_expr(
            "category",
            values = c(
                "music", "bar", "theatre",
                "bicycle"
            ),
            stops = c(
                "#1f78b4", "#33a02c",
                "#e31a1c", "#ff7f00"
            )
        ),
        circle_radius = 8,
        circle_stroke_color = "#ffffff",
        circle_stroke_width = 2,
        circle_opacity = 0.8,
        tooltip = "category",
        hover_options = list(
            circle_radius = 12,
            circle_color = "#ffff99"
        )
    ) %>%
    add_categorical_legend(
        legend_title = "Points of Interest",
        values = c("Music", "Bar", "Theatre", "Bicycle"),
        colors = c("#1f78b4", "#33a02c", "#e31a1c", "#ff7f00"),
        circular_patches = TRUE
    )
## End(Not run)