Interactive leaflet map for classified rasters — dft_map

Build a toggleable leaflet map from classified SpatRasters or remote COG URLs served via titiler. Includes layer control, legend, and fullscreen.

Usage

dft_map_interactive(
  x,
  aoi = NULL,
  class_table = NULL,
  source = "io-lulc",
  titiler_url = getOption("drift.titiler_url"),
  basemaps = c(Light = "CartoDB.Positron", Satellite = "Esri.WorldImagery"),
  legend_position = "bottomright",
  zoom = 14
)

Arguments

x: A named list of classified terra::SpatRasters (e.g. from dft_rast_classify()) or a named character vector of COG URLs. A single SpatRaster or URL string is auto-wrapped into a length-1 list/vector. Names become the layer toggle labels (years, seasons, etc.).
aoi: An sf polygon for the area of interest outline. NULL (default) omits the AOI layer.
class_table: A tibble with columns code, class_name, color (hex). When NULL, loaded via dft_class_table() using source.
source: Character. Used to load a shipped class table when class_table is NULL. One of "io-lulc" or "esa-worldcover".
titiler_url: Base URL of a titiler instance (e.g. "https://titiler.example.com"). Only used when x contains COG URLs. Defaults to getOption("drift.titiler_url"). If NULL in COG mode, an error is raised prompting the user to set the option.
basemaps: Named character vector of provider tile IDs. The first element is the default basemap. Names become radio button labels.
legend_position: Legend placement passed to leaflet::addLegend(). Set to NULL to suppress the legend.
zoom: Initial zoom level.

Value

A leaflet::leaflet htmlwidget. The first layer in x is visible by default; other layers are hidden but toggleable.

Examples

# Single classified raster — returns a leaflet widget
r <- terra::rast(system.file("extdata", "example_2020.tif", package = "drift"))
classified <- dft_rast_classify(r, source = "io-lulc")
map <- dft_map_interactive(classified)
class(map)
#> [1] "leaflet"    "htmlwidget"

# Multiple years with AOI — toggle between time periods
aoi <- sf::st_read(
  system.file("extdata", "example_aoi.gpkg", package = "drift"),
  quiet = TRUE
)
files <- c("2017" = "example_2017.tif", "2020" = "example_2020.tif",
           "2023" = "example_2023.tif")
rasters <- lapply(files, function(f) {
  terra::rast(system.file("extdata", f, package = "drift"))
})
classified <- dft_rast_classify(rasters, source = "io-lulc")
map <- dft_map_interactive(classified, aoi = aoi)
if (interactive()) map

if (FALSE) { # \dontrun{
# Remote COGs via titiler (requires options(drift.titiler_url = "..."))
cogs <- c("2017" = "https://bucket.s3.amazonaws.com/lulc_2017.tif",
          "2023" = "https://bucket.s3.amazonaws.com/lulc_2023.tif")
dft_map_interactive(cogs, source = "io-lulc")
} # }