Paris Trees

Heatmap of 5,000 trees managed by the City of Paris, weighted by tree height.

Layers: HeatmapLayer + ScatterplotLayer | Map: Voyager

Code

url = "https://opendata.paris.fr/api/explore/v2.1/catalog/datasets/les-arbres/exports/geojson?limit=5000"
response = JSON3.read(read(Downloads.download(url), String))
features = response[:features]

lngs = Float64[]
lats = Float64[]
heights = Float64[]
for f in features
    geo = f[:geometry]
    geo === nothing && continue
    coords = geo[:coordinates]
    push!(lngs, Float64(coords[1]))
    push!(lats, Float64(coords[2]))
    h = get(f[:properties], :hauteurenm, nothing)
    push!(heights, h !== nothing && h isa Number ? Float64(h) : 5.0)
end

data = (lng = lngs, lat = lats, height = heights)

heat = HeatmapLayer(
    data = data,
    get_position = [:lng, :lat],
    get_weight = :height,
    radius_pixels = 30,
    intensity = 1.2,
    threshold = 0.03,
    color_range = [
        [255, 255, 178, 25],
        [254, 217, 118, 85],
        [254, 178, 76, 127],
        [253, 141, 60, 170],
        [240, 59, 32, 210],
        [189, 0, 38, 240],
    ],
    opacity = 0.7,
)
scatter = ScatterplotLayer(
    data = data,
    get_position = [:lng, :lat],
    get_fill_color = [34, 139, 34, 80],
    get_radius = 5,
    radius_min_pixels = 1,
    opacity = 0.3,
)

Deck(
    [heat, scatter],
    initial_view_state = ViewState(longitude = 2.34, latitude = 48.86, zoom = 12.5),
    map_style = "https://basemaps.cartocdn.com/gl/voyager-gl-style/style.json",
)