Map modeled evacuation bottlenecks — map_evac

Creates a route-density raster and identifies high-use modeled evacuation corridors from supplied least-cost paths or an run_evacpath() result created with keep_routes = TRUE.

Usage

map_evac_bottlenecks(
  routes = NULL,
  evac_result = NULL,
  template = NULL,
  quantile_threshold = 0.9,
  min_count = NULL,
  rescale = FALSE,
  return_polygons = TRUE,
  ...
)

Arguments

routes: An sf or SpatVector line layer of modeled routes.
evac_result: Optional output from run_evacpath() containing retained routes.
template: Optional SpatRaster defining the density grid. When omitted, the function attempts to infer a template from evac_result.
quantile_threshold: Numeric value between 0 and 1. Used to select high-density route cells when min_count is NULL.
min_count: Optional numeric minimum density count. When supplied, this takes precedence over quantile_threshold.
rescale: Logical passed to leastcostpath::create_lcp_density().
return_polygons: Logical. Convert high-density raster cells to polygons.
...: Reserved for future extensions.

Value

An evac_bottleneck list with density rasters, optional polygons, threshold value, and summary.

Examples

template <- terra::rast(nrows = 5, ncols = 5, xmin = 0, xmax = 5, ymin = 0, ymax = 5,
  vals = 1, crs = "EPSG:3857")
routes <- sf::st_sf(
  route = c("a", "b"),
  geometry = sf::st_sfc(
    sf::st_linestring(matrix(c(0.5, 0.5, 4.5, 4.5), ncol = 2, byrow = TRUE)),
    sf::st_linestring(matrix(c(0.5, 4.5, 4.5, 0.5), ncol = 2, byrow = TRUE)),
    crs = 3857
  )
)
map_evac_bottlenecks(routes = routes, template = template)
#> <evac_bottleneck>
#>  n_routes max_density threshold_value area_high_density_m2
#>         2           2             1.2                    1
#>  percent_of_route_area_high_density
#>                            11.11111