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Calculate minimum least-cost distance from origins to safety

Source: R/distance_time_polygons.R
calc_min_distance_to_safety.Rd

For each origin point, calculates least-cost paths to all candidate safety points and stores the shortest finite path distance. Destination points are appended to the output with distance equal to zero.

Usage

calc_min_distance_to_safety(
  cs,
  origins,
  destinations,
  include_destinations = TRUE,
  progress = FALSE,
  progress_every = 1L,
  check_locations = FALSE,
  return_routes = FALSE
)

Arguments

cs

A leastcostpath conductance surface.

origins

Origin points.

destinations

Escape/safety destination points.

include_destinations

Logical. Add destination points with distance = 0.

progress

Logical. Print simple progress messages.

progress_every

Integer. Print progress every n origins when progress = TRUE.

check_locations

Logical passed to leastcostpath::create_lcp(). The default is FALSE for speed after inputs have already been projected and cropped.

return_routes

Logical. If TRUE, return the selected shortest route for each reachable origin alongside the distance points. The default is FALSE to preserve the original return type and avoid storing route geometries when they are not needed.

Value

A point SpatVector with columns distance and type. When return_routes = TRUE, returns a list with distance_points, routes, and unreachable_origins.

Examples

dem <- terra::rast(nrows = 5, ncols = 5, xmin = 0, xmax = 5, ymin = 0, ymax = 5,
  vals = 1, crs = "EPSG:3857")
cs <- make_conductance_surface(dem)
#> calculating slope...
#> Applying tobler cost function
origins <- terra::vect(data.frame(x = 0.5, y = 0.5), geom = c("x", "y"), crs = "EPSG:3857")
destinations <- terra::vect(data.frame(x = 4.5, y = 4.5), geom = c("x", "y"), crs = "EPSG:3857")
calc_min_distance_to_safety(cs, origins, destinations)
#> class       : SpatVector
#> geometry    : points
#> dimensions  : 2, 2  (geometries, attributes)
#> extent      : 0.5, 4.5, 0.5, 4.5  (xmin, xmax, ymin, ymax)
#> coord. ref. : WGS 84 / Pseudo-Mercator
#> names       : distance   type
#> type        :    <num>  <chr>
#> values      :  5.65685   road
#>                      0 escape