R/make_grid.R
st_make_grid.Rd
Create a square or hexagonal grid covering the bounding box of the geometry of an sf or sfc object
numeric of length 1 or 2 with target cellsize: for square or rectangular cells the width and height, for hexagonal cells the distance between opposite edges (edge length is cellsize/sqrt(3)). A length units object can be passed, or an area unit object with area size of the square or hexagonal cell.
numeric of length 2; lower left corner coordinates (x, y) of the grid
integer of length 1 or 2, number of grid cells in x and y direction (columns, rows)
object of class crs
; coordinate reference system of the target of the target grid in case argument x
is missing, if x
is not missing, its crs is inherited.
character; one of: "polygons"
, "corners"
, or "centers"
logical; if FALSE
, create hexagonal grid
logical; if TRUE
generate flat topped hexagons, else generate pointy topped
Object of class sfc
(simple feature geometry list column) with, depending on what
and square
,
square or hexagonal polygons, corner points of these polygons, or center points of these polygons.
plot(st_make_grid(what = "centers"), axes = TRUE)
plot(st_make_grid(what = "corners"), add = TRUE, col = 'green', pch=3)
sfc = st_sfc(st_polygon(list(rbind(c(0,0), c(1,0), c(1,1), c(0,0)))))
plot(st_make_grid(sfc, cellsize = .1, square = FALSE))
plot(sfc, add = TRUE)
# non-default offset:
plot(st_make_grid(sfc, cellsize = .1, square = FALSE, offset = c(0, .05 / (sqrt(3)/2))))
plot(sfc, add = TRUE)
nc = st_read(system.file("shape/nc.shp", package="sf"))
#> Reading layer `nc' from data source
#> `/tmp/RtmpxmZ5jE/temp_libpathf41261b39098/sf/shape/nc.shp'
#> using driver `ESRI Shapefile'
#> Simple feature collection with 100 features and 14 fields
#> Geometry type: MULTIPOLYGON
#> Dimension: XY
#> Bounding box: xmin: -84.32385 ymin: 33.88199 xmax: -75.45698 ymax: 36.58965
#> Geodetic CRS: NAD27
g = st_make_grid(nc)
plot(g)
plot(st_geometry(nc), add = TRUE)
# g[nc] selects cells that intersect with nc:
plot(g[nc], col = '#ff000088', add = TRUE)