R/draw_hexTiles.R

In rxlacroix/tilegram: Create a Tilegram from a sf Object

#' Draw hexagon tiles
#'
#' Draw a grid of tessellated hexagons over the bounding box of a SpatialPolygons object
#'
#' @param x An sp object
#' @param cellsize The size of the hexagons, if left blank then will take the average area of the polygons in the SpatialPolygons data.frame
#'
#' @return A SpatialPolygonsDataFrame of tessellated hexagons covering the bounding box of a SpatialPolygons
#' @export
#'

draw_hexTiles <- function(area, offset_x_start = 0, offset_x_end = 4, offset_y_start = 0, offset_y_end = 4) {
  grid <- expand.grid(offset_x_start:offset_x_end, offset_y_start:offset_y_end)
  grid$tessellate <- grid[, 2] %% 2 == 0

  hexes <- sp::SpatialPolygons(lapply(1:nrow(grid), function(i) {
    draw_hex(area, offset_x = grid[i, 1], offset_y = grid[i, 2], id = i, tessellate = grid[i, 3])
  }))

  names(grid) <- c("offset_x", "offset_y", "tessellate")

  grid <- data.frame(id = 1:nrow(grid), grid)

  sp::SpatialPolygonsDataFrame(hexes, grid)
}