areaOfEffect (version 0.2.4)

aoe_sample.aoe_border_result: Stratified Sampling from Border AoE Results

Description

Sample points from an aoe_border_result with control over side and/or core/halo balance.

Usage

# S3 method for aoe_border_result
aoe_sample(
  x,
  n = NULL,
  ratio = NULL,
  by = c("side", "class"),
  replace = FALSE,
  ...
)

Value

An aoe_border_result object containing the sampled points.

Arguments

x

An aoe_border_result object returned by aoe_border().

n

Total number of points to sample. If NULL, uses all available points subject to the ratio constraint.

ratio

Named numeric vector specifying target proportions. Names should match the side names used in aoe_border() (e.g., c(side_1 = 0.5, side_2 = 0.5)) or use c(core = 0.5, halo = 0.5) for distance-based sampling. Must sum to 1.

by

Character. What to stratify by:

• "side" (default): sample by side of the border

• "class": sample by core/halo classification

replace

Logical. Sample with replacement? Default is FALSE.

...

Additional arguments (ignored).

Examples

library(sf)

# Create a border line
border <- st_as_sf(
  data.frame(id = 1),
  geometry = st_sfc(st_linestring(matrix(
    c(0, 0, 100, 100), ncol = 2, byrow = TRUE
  ))),
  crs = 32631
)

# Create points
pts <- st_as_sf(
  data.frame(id = 1:6),
  geometry = st_sfc(
    st_point(c(10, 20)),
    st_point(c(30, 10)),
    st_point(c(50, 80)),
    st_point(c(80, 40)),
    st_point(c(5, 5)),
    st_point(c(95, 95))
  ),
  crs = 32631
)

result <- aoe_border(pts, border, width = 20,
                     side_names = c("west", "east"))

# Equal sampling from each side
balanced <- aoe_sample(result, ratio = c(west = 0.5, east = 0.5))

# Sample by core/halo instead
by_class <- aoe_sample(result, ratio = c(core = 0.5, halo = 0.5),
                       by = "class")