Generate a Grid of Points Over a Spatial Extent — generate_grid

Creates a regular grid of points covering the (optionally expanded) extent of a spatial object at a specified resolution. Accepts either an sf object or a SpatVector as input. The output will match the input class.

Usage

generate_grid_points(site_point, expansion_dist, resolution)

Arguments

site_point: A spatial point or set of points, either an sf object or a SpatVector. The extent of this object defines the initial bounds of the grid.
expansion_dist: Numeric vector of length 1 or 2. Distance (in map units) to expand the bounding box in the x and y directions. If a single value is provided, it is used for both directions. To use the exact extent of site_point, set this to 0.
resolution: Numeric vector of length 1 or 2. The spacing between grid points in the x and y directions (in map units). If a single value is provided, it is used for both directions.

Value

A grid of points with regular spacing, returned as the same class as site_point (either sf or SpatVector). Each point includes a site variable identifying its row index (1 to n).

Examples

# single point ----------------------------
site_pt <- terra::vect(
  data.frame(x = -76.67587, y = 34.71413),
  geom = c("x", "y"),
  crs = "EPSG:4326"
  )

# Create a grid of points covering an area expanded by 0.001° (x) and 0.0002°
# (y) # around the input point, with grid points spaced every 0.0001° (x) and
# 0.00005° (y)
grid_pts <- generate_grid_points(
  site_point = site_pt,
  expansion_dist = c(0.001, 0.0002),
  resolution = c(0.0001, 0.00005)
 )

# terra::plot(grid_pts)

# multiple points ---------------------------
site_pts <- terra::vect(
  data.frame(
    x = c(346536.4, 346986.4, 346986.4),
    y = c(3842620,  3842670,  3843270)),
  geom = c("x", "y"),
  crs = "EPSG:26918")

# create a grid of points covering an area expanded by 1000 map units
# (meters) with points spaced every 50 map units (meters)
grid_pts <- generate_grid_points(
  site_point = site_pts,
  expansion_dist = 1000,
  resolution = 50
 )

# terra::plot(grid_pts)