Composite Sampling

Generates sampling points for composite sampling from equal-area strata. Multiple samples per stratum are grouped into composites.

Usage

ss_composite(
  x,
  n_strata = NULL,
  n_composites,
  n_try = 1L,
  n_cells = 2500L,
  seed = NULL,
  verbose = FALSE
)

Arguments

x

An sf object representing the study area, OR an ss_strata object with equal_area = TRUE.

n_strata

Integer, number of strata. Only used if x is an sf object.

n_composites

Integer, number of composite samples to create.

n_try

Integer, number of random initializations (default 1).

n_cells

Integer, approximate number of grid cells (default 2500).

seed

Optional integer seed for reproducibility.

verbose

Logical, whether to print progress (default FALSE).

Value

An object of class ss_samples with a composite column indicating composite group membership.

Details

Composite sampling is used when individual samples are combined before analysis. This function creates equal-area strata and generates multiple random samples per stratum, grouped into composite samples.

Each composite includes one sample from each stratum.

See also

ss_coverage_equal_area(), ss_stratified()

Examples

library(sf)
#> Linking to GEOS 3.12.1, GDAL 3.8.4, PROJ 9.4.0; sf_use_s2() is TRUE
poly <- st_polygon(list(rbind(c(0, 0), c(100, 0), c(100, 50), c(0, 50), c(0, 0))))
study_area <- st_sf(geometry = st_sfc(poly))

# Create 3 composite samples from 20 strata
samples <- ss_composite(study_area, n_strata = 20, n_composites = 3)