Compute Area Statistics for AoE — aoe

Calculate area statistics for the original supports and their areas of effect, including expansion ratios, masking effects, and core/halo balance.

Usage

aoe_area(x)

Arguments

x: An aoe_result object returned by aoe().

Value

An aoe_area_result data frame with one row per support:

support_id: Support identifier
area_core: Area of core region (same as original support)
area_halo: Area of halo region (AoE minus core, after masking)
area_aoe: Total AoE area after masking
halo_core_ratio: Ratio of halo to core area (theoretically 3.0 without mask)
pct_masked: Percentage of theoretical AoE area removed by masking

Details

With scale \(s\), the AoE expands by multiplier \((1+s)\) from centroid, resulting in \((1+s)^2\) times the area. The theoretical halo:core ratio is \((1+s)^2 - 1\):

Scale 1 (default): ratio 3.0 (core 1 part, halo 3 parts)
Scale 0.414: ratio 1.0 (equal areas)

Masking reduces the halo (and thus the ratio) when the AoE extends beyond hard boundaries.

Examples

library(sf)

support <- st_as_sf(
  data.frame(id = 1),
  geometry = st_sfc(st_polygon(list(
    cbind(c(0, 10, 10, 0, 0), c(0, 0, 10, 10, 0))
  ))),
  crs = 32631
)

pts <- st_as_sf(
  data.frame(id = 1:3),
  geometry = st_sfc(
    st_point(c(5, 5)),
    st_point(c(15, 5)),
    st_point(c(2, 2))
  ),
  crs = 32631
)

result <- aoe(pts, support)
aoe_area(result)