Create and Format Geography Vectors

These functions create and export geography vectors. Unlike the BigQuery geography constructors, these functions do not sanitize invalid or redundant input using s2_union(). Note that when creating polygons using s2_make_polygon(), rings can be open or closed.

s2_geog_point(longitude, latitude)

s2_make_line(longitude, latitude, feature_id = 1L)

s2_make_polygon(
  longitude,
  latitude,
  feature_id = 1L,
  ring_id = 1L,
  oriented = FALSE,
  check = TRUE
)

s2_geog_from_text(
  wkt_string,
  oriented = FALSE,
  check = TRUE,
  planar = FALSE,
  tessellate_tol_m = s2_tessellate_tol_default()
)

s2_geog_from_wkb(
  wkb_bytes,
  oriented = FALSE,
  check = TRUE,
  planar = FALSE,
  tessellate_tol_m = s2_tessellate_tol_default()
)

s2_as_text(
  x,
  precision = 16,
  trim = TRUE,
  planar = FALSE,
  tessellate_tol_m = s2_tessellate_tol_default()
)

s2_as_binary(
  x,
  endian = wk::wk_platform_endian(),
  planar = FALSE,
  tessellate_tol_m = s2_tessellate_tol_default()
)

s2_tessellate_tol_default()

Arguments

longitude, latitude: Vectors of latitude and longitude
feature_id, ring_id: Vectors for which a change in sequential values indicates a new feature or ring. Use factor() to convert from a character vector.
oriented: TRUE if polygon ring directions are known to be correct (i.e., exterior rings are defined counter clockwise and interior rings are defined clockwise).
check: Use check = FALSE to skip error on invalid geometries
wkt_string: Well-known text
planar: Use TRUE to force planar edges in import or export.
tessellate_tol_m: The maximum number of meters to that a point must be moved to satisfy the planar edge constraint.
wkb_bytes: A list() of raw()
x: geography vectors. These inputs are passed to as_s2_geography(), so you can pass other objects (e.g., character vectors of well-known text) directly.
precision: The number of significant digits to export when writing well-known text. If trim = FALSE, the number of digits after the decimal place.
trim: Should trailing zeroes be included after the decimal place?
endian: The endian-ness of the well-known binary. See wk::wkb_translate_wkb().

Examples

# create point geographies using coordinate values:
s2_geog_point(-64, 45)
#> <geodesic s2_geography[1] with CRS=OGC:CRS84>
#> [1] POINT (-64 45)

# create line geographies using coordinate values:
s2_make_line(c(-64, 8), c(45, 71))
#> <geodesic s2_geography[1] with CRS=OGC:CRS84>
#> [1] LINESTRING (-64 45, 8 71)

# optionally, separate features using feature_id:
s2_make_line(
  c(-64, 8, -27, -27), c(45, 71, 0, 45),
  feature_id = c(1, 1, 2, 2)
)
#> <geodesic s2_geography[2] with CRS=OGC:CRS84>
#> [1] LINESTRING (-64 45, 8 71)  LINESTRING (-27 0, -27 45)

# create polygon geographies using coordinate values:
# (rings can be open or closed)
s2_make_polygon(c(-45, 8, 0), c(64, 71, 90))
#> <geodesic s2_geography[1] with CRS=OGC:CRS84>
#> [1] POLYGON ((-45 64, 8 71, 0 90, -45 64))

# optionally, separate rings and/or features using
# ring_id and/or feature_id
s2_make_polygon(
  c(20, 10, 10, 30, 45, 30, 20, 20, 40, 20, 45),
  c(35, 30, 10, 5, 20, 20, 15, 25, 40, 45, 30),
  feature_id = c(rep(1, 8), rep(2, 3)),
  ring_id = c(1, 1, 1, 1, 1, 2, 2, 2, 1, 1, 1)
)
#> <geodesic s2_geography[2] with CRS=OGC:CRS84>
#> [1] POLYGON ((20 35, 10 30, 10 10, 30 5, 45 20...
#> [2] POLYGON ((40 40, 20 45, 45 30, 40 40))       

# import and export well-known text
(geog <- s2_geog_from_text("POINT (-64 45)"))
#> <geodesic s2_geography[1] with CRS=OGC:CRS84>
#> [1] POINT (-64 45)
s2_as_text(geog)
#> [1] "POINT (-64 45)"

# import and export well-known binary
(geog <- s2_geog_from_wkb(wk::as_wkb("POINT (-64 45)")))
#> <geodesic s2_geography[1] with CRS=OGC:CRS84>
#> [1] POINT (-64 45)
s2_as_binary(geog)
#> [[1]]
#>  [1] 01 01 00 00 00 00 00 00 00 00 00 50 c0 00 00 00 00 00 80 46 40
#> 
#> attr(,"class")
#> [1] "blob"

# import geometry from planar space
s2_geog_from_text(
   "POLYGON ((0 0, 1 0, 0 1, 0 0))",
   planar = TRUE,
   tessellate_tol_m = 1
)
#> <geodesic s2_geography[1] with CRS=OGC:CRS84>
#> [1] POLYGON ((0 0, 1 0, 0.5 0.5, 0.25 0.75, 0 1...

# export geographies into planar space
geog <- s2_make_polygon(c(179, -179, 179), c(10, 10, 11))
s2_as_text(geog, planar = TRUE)
#> [1] "POLYGON ((179 10, 180 10.00149252698408, 181 10, 180.0016175935936 10.50156386165192, 179 11, 179 10))"

# polygons containing a pole need an extra step
geog <- s2_data_countries("Antarctica")
geom <- s2_as_text(
  s2_intersection(geog, s2_world_plate_carree()),
  planar = TRUE
)

Arguments

See also

Examples