GRTS

src/BiodiversityObservationNetworks.jl

@@ -40,6 +40,9 @@ export CubeSampling
 include("fractaltriad.jl")
 export FractalTriad
 
+include("grts.jl")
+export GeneralizedRandomTessellatedStratified
+
 include("uniqueness.jl")
 export Uniqueness
 

src/grts.jl

@@ -0,0 +1,69 @@
+"""
+    GeneralizedRandomTessellatedStratified
+
+@Olsen
+"""
+@kwdef struct GeneralizedRandomTessellatedStratified <: BONSeeder
+    numsites = 50
+    dims = (100, 100)
+end
+
+maxsites(grts::GeneralizedRandomTessellatedStratified) = prod(dims)
+
+function check_arguments(grts::GeneralizedRandomTessellatedStratified)
+    check(TooManySites, grts)
+    check(TooFewSites, grts)
+    return
+end
+
+function _quadrant_fill!(mat)
+    x, y = size(mat)
+    a, b = x ÷ 2, y ÷ 2
+    quad_ids = shuffle([1, 2, 3, 4])
+    mat[begin:a, begin:b] .= quad_ids[1]
+    mat[(a + 1):end, begin:b] .= quad_ids[2]
+    mat[begin:a, (b + 1):end] .= quad_ids[3]
+    mat[(a + 1):end, (b + 1):end] .= quad_ids[4]
+    return mat
+end
+
+function _quadrant_split!(mat, grid_size)
+    x, y = size(mat)
+
+    num_x_grids, num_y_grids = x ÷ grid_size, y ÷ grid_size
+
+    for i in 0:(num_x_grids - 1), j in 0:(num_y_grids - 1)
+        a, b = i * grid_size, j * grid_size
+        bounds = (a + 1, b + 1), (a + grid_size, b + grid_size)
+        mat[bounds[1][1]:bounds[2][1], bounds[1][2]:bounds[2][2]] .=
+            _quadrant_fill!(mat[bounds[1][1]:bounds[2][1], bounds[1][2]:bounds[2][2]])
+    end
+
+    return mat
+end
+
+"""
+_generate!(coords::Vector{CartesianIndex}, grts::GeneralizedRandomTessellatedStratified)
+"""
+function _generate!(
+    coords::Vector{CartesianIndex},
+    grts::GeneralizedRandomTessellatedStratified,
+)
+    x, y = grts.dims # smallest multiple of 4 on each side
+    num_address_grids = Int(ceil(max(log(2, x), log(2, y))))
+
+    grid_sizes = reverse([2^i for i in 1:num_address_grids])
+
+    address_grids =
+        [zeros(Int, 2^num_address_grids, 2^num_address_grids) for _ in grid_sizes]
+
+    map(
+        i -> _quadrant_split!(address_grids[i], grid_sizes[i]),
+        eachindex(address_grids),
+    )
+
+    code_numbers = sum([10^(i - 1) .* ag for (i, ag) in enumerate(address_grids)])
+    sort_idx = sortperm([code_numbers[cidx] for cidx in eachindex(code_numbers)])
+
+    return coords .= CartesianIndices(code_numbers)[sort_idx][1:(grts.numsites)]
+end