Places axis‑aligned rectangular quadrats at random locations inside domain, rejecting candidates that either (i) are not fully contained or (ii) overlap any previously accepted quadrat. A simple rejection‑sampling loop is used with a finite attempt budget.
Arguments
- domain
An sf polygon/multipolygon defining the sampling region. Must carry a valid projected CRS suitable for linear units.
- n_quadrats
Integer (≥1). Target number of non‑overlapping quadrats to place.
- quadrat_size
Numeric vector of length 2, c(width, height), giving quadrat dimensions in the same units as the domain CRS. Both values must be positive and finite.
Value
An sf object (polygons) with:
- quadrat_id
Sequential integer identifier for each placed quadrat.
- geometry
Axis‑aligned rectangular polygon for the quadrat.
If no valid placement is possible, returns an empty sf with the same CRS and emits a warning.
Details
Each candidate center is drawn uniformly from the domain’s bounding box, shrunk so the full rectangle of size quadrat_size = c(width, height) fits inside. The resulting polygon is accepted only if it is entirely within domain and non‑overlapping with all accepted quadrats.
The loop stops when n_quadrats are placed or after n_quadrats * 100 attempts (a warning is issued if the target is not met).
CRS: Use a projected CRS (e.g., meters). quadrat_size is interpreted in the CRS linear units.
Reproducibility: Set a seed (e.g., set.seed(...)) before calling to obtain repeatable placements.
See also
place_quadrats_systematic (regular grid),
place_quadrats_tiled (systematic tiling by cell size),
place_quadrats_voronoi (Voronoi‑based centers),
place_quadrats_transect (parallel transects)