chopin (version 0.9.4)

par_merge_grid: Merge adjacent grid polygons with given rules

Description

Merge boundary-sharing (in "Rook" contiguity) grids with fewer target features than the threshold. This function strongly assumes that the input is returned from the internal function par_make_grid, which has "CGRIDID" as the unique id field.

Usage

par_merge_grid(
  points_in = NULL,
  grid_in = NULL,
  grid_min_features = NULL,
  merge_max = 4L
)

Value

A sf or SpatVector object of computation grids.

Arguments

points_in

sf or SpatVector object. Target points of computation.

grid_in

sf or SpatVector object. The grid generated by the internal function par_make_grid.

grid_min_features

integer(1). Threshold to merge adjacent grids.

merge_max

integer(1). Maximum number of grids to merge per merged set. Default is 4. For example, if the number of grids to merge is 20 and merge_max is 10, the function will split the 20 grids into two sets of 10 grids.

Author

Insang Song

References

• Polsby DD, Popper FJ. (1991). The Third Criterion: Compactness as a Procedural Safeguard Against Partisan Gerrymandering. Yale Law & Policy Review, 9(2), 301–353.

See Also

Other Parallelization: par_cut_coords(), par_grid(), par_grid_mirai(), par_hierarchy(), par_hierarchy_mirai(), par_make_grid(), par_multirasters(), par_multirasters_mirai(), par_pad_balanced(), par_pad_grid(), par_split_list()

Examples

lastpar <- par(mfrow = c(1, 1))
library(sf)
library(igraph)
library(dplyr)
library(spatstat.random)
options(sf_use_s2 = FALSE)

dg <- sf::st_as_sfc(st_bbox(c(xmin = 0, ymin = 0, xmax = 8e5, ymax = 6e5)))
sf::st_crs(dg) <- 5070
dgs <- sf::st_as_sf(st_make_grid(dg, n = c(20, 15)))
dgs$CGRIDID <- seq(1, nrow(dgs))

dg_sample <- sf::st_sample(dg, kappa = 5e-9, mu = 15,
scale = 15000, type = "Thomas")
sf::st_crs(dg_sample) <- sf::st_crs(dg)
dg_merged <- par_merge_grid(sf::st_as_sf(dg_sample), dgs, 100)

plot(sf::st_geometry(dg_merged))
par(lastpar)