s2_geog_point: Create and Format Geography Vectors

In s2: Spherical Geometry Operators Using the S2 Geometry Library

Create and Format Geography Vectors

Description

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.

Usage

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	An object that can be converted to an s2_geography vector
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().

See Also

See as_s2_geography() for other ways to construct geography vectors.

BigQuery's geography function reference:

• ST_GEOGPOINT

• ST_MAKELINE

• ST_MAKEPOLYGON

• ST_GEOGFROMTEXT

• ST_GEOGFROMWKB

• ST_ASTEXT

• ST_ASBINARY

Examples

# create point geographies using coordinate values:
s2_geog_point(-64, 45)

# create line geographies using coordinate values:
s2_make_line(c(-64, 8), c(45, 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)
)

# create polygon geographies using coordinate values:
# (rings can be open or closed)
s2_make_polygon(c(-45, 8, 0), c(64, 71, 90))

# 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)
)

# import and export well-known text
(geog <- s2_geog_from_text("POINT (-64 45)"))
s2_as_text(geog)

# import and export well-known binary
(geog <- s2_geog_from_wkb(wk::as_wkb("POINT (-64 45)")))
s2_as_binary(geog)

# import geometry from planar space
s2_geog_from_text(
   "POLYGON ((0 0, 1 0, 0 1, 0 0))",
   planar = TRUE,
   tessellate_tol_m = 1
)

# export geographies into planar space
geog <- s2_make_polygon(c(179, -179, 179), c(10, 10, 11))
s2_as_text(geog, planar = TRUE)

# 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
)

s2 documentation built on May 31, 2023, 9:33 p.m.