These functions operate on one or more geography vectors and return a geography vector.

```
s2_boundary(x)
s2_centroid(x)
s2_closest_point(x, y)
s2_minimum_clearance_line_between(x, y)
s2_difference(x, y, options = s2_options())
s2_sym_difference(x, y, options = s2_options())
s2_intersection(x, y, options = s2_options())
s2_union(x, y = NULL, options = s2_options())
s2_snap_to_grid(x, grid_size)
s2_simplify(x, tolerance, radius = s2_earth_radius_meters())
s2_rebuild(x, options = s2_options())
s2_buffer_cells(
x,
distance,
max_cells = 1000,
min_level = -1,
radius = s2_earth_radius_meters()
)
s2_convex_hull(x)
s2_centroid_agg(x, na.rm = FALSE)
s2_coverage_union_agg(x, options = s2_options(), na.rm = FALSE)
s2_rebuild_agg(x, options = s2_options(), na.rm = FALSE)
s2_union_agg(x, options = s2_options(), na.rm = FALSE)
s2_convex_hull_agg(x, na.rm = FALSE)
s2_point_on_surface(x, na.rm = FALSE)
```

- 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.- y
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.- options
An

`s2_options()`

object describing the polygon/polyline model to use and the snap level.- grid_size
The grid size to which coordinates should be snapped; will be rounded to the nearest power of 10.

- tolerance
The minimum distance between vertexes to use when simplifying a geography.

- radius
Radius of the earth. Defaults to the average radius of the earth in meters as defined by

`s2_earth_radius_meters()`

.- distance
The distance to buffer, in units of

`radius`

.- max_cells
The maximum number of cells to approximate a buffer.

- min_level
The minimum cell level used to approximate a buffer (1 - 30). Setting this value too high will result in unnecessarily large geographies, but may help improve buffers along long, narrow regions.

- na.rm
For aggregate calculations use

`na.rm = TRUE`

to drop missing values.

The geometry model indicates whether or not a geometry includes its boundaries.
Boundaries of line geometries are its end points.
OPEN geometries do not contain their boundary (`model = "open"`

); CLOSED
geometries (`model = "closed"`

) contain their boundary; SEMI-OPEN geometries
(`model = "semi-open"`

) contain half of their boundaries, such that when two polygons
do not overlap or two lines do not cross, no point exist that belong to
more than one of the geometries. (This latter form, half-closed, is
not present in the OpenGIS "simple feature access" (SFA) standard nor DE9-IM on
which that is based). The default values for `s2_contains()`

(open)
and covers/covered_by (closed) correspond to the SFA standard specification
of these operators.

BigQuery's geography function reference:

```
# returns the boundary:
# empty for point, endpoints of a linestring,
# perimeter of a polygon
s2_boundary("POINT (-64 45)")
#> <geodesic s2_geography[1] with CRS=OGC:CRS84>
#> [1] GEOMETRYCOLLECTION EMPTY
s2_boundary("LINESTRING (0 0, 10 0)")
#> <geodesic s2_geography[1] with CRS=OGC:CRS84>
#> [1] MULTIPOINT ((0 0), (10 0))
s2_boundary("POLYGON ((0 0, 10 0, 10 10, 0 10, 0 0))")
#> <geodesic s2_geography[1] with CRS=OGC:CRS84>
#> [1] LINESTRING (0 0, 10 0, 10 10, 0 10, 0 0...
# returns the area-weighted centroid, element-wise
s2_centroid("POLYGON ((0 0, 10 0, 10 10, 0 10, 0 0))")
#> <geodesic s2_geography[1] with CRS=OGC:CRS84>
#> [1] POINT (5 5.00595863)
s2_centroid("LINESTRING (0 0, 10 0)")
#> <geodesic s2_geography[1] with CRS=OGC:CRS84>
#> [1] POINT (5 0)
# s2_point_on_surface guarantees a point on surface
# Note: this is not the same as st_point_on_surface
s2_centroid("POLYGON ((0 0, 10 0, 1 1, 0 10, 0 0))")
#> <geodesic s2_geography[1] with CRS=OGC:CRS84>
#> [1] POINT (2.00377112 2.00234355)
s2_point_on_surface("POLYGON ((0 0, 10 0, 1 1, 0 10, 0 0))")
#> <geodesic s2_geography[1] with CRS=OGC:CRS84>
#> [1] POINT (0.450236802 0.450222902)
# returns the unweighted centroid of the entire input
s2_centroid_agg(c("POINT (0 0)", "POINT (10 0)"))
#> <geodesic s2_geography[1] with CRS=OGC:CRS84>
#> [1] POINT (5 0)
# returns the closest point on x to y
s2_closest_point(
"POLYGON ((0 0, 10 0, 10 10, 0 10, 0 0))",
"POINT (0 90)" # north pole!
)
#> <geodesic s2_geography[1] with CRS=OGC:CRS84>
#> [1] POINT (5 10.037423)
# returns the shortest possible line between x and y
s2_minimum_clearance_line_between(
"POLYGON ((0 0, 10 0, 10 10, 0 10, 0 0))",
"POINT (0 90)" # north pole!
)
#> <geodesic s2_geography[1] with CRS=OGC:CRS84>
#> [1] LINESTRING (5 10.037423, 0 90)
# binary operations: difference, symmetric difference, intersection and union
s2_difference(
"POLYGON ((0 0, 10 0, 10 10, 0 10, 0 0))",
"POLYGON ((5 5, 15 5, 15 15, 5 15, 5 5))",
# 32 bit platforms may need to set snap rounding
s2_options(snap = s2_snap_level(30))
)
#> <geodesic s2_geography[1] with CRS=OGC:CRS84>
#> [1] POLYGON ((5.00000004 10.0374231, 3.55739019e-08 10, 3.55739019e-08 3.55739019e-08, 10 3.50334544e-08, 10 5.01900178...
s2_sym_difference(
"POLYGON ((0 0, 10 0, 10 10, 0 10, 0 0))",
"POLYGON ((5 5, 15 5, 15 15, 5 15, 5 5))",
# 32 bit platforms may need to set snap rounding
s2_options(snap = s2_snap_level(30))
)
#> <geodesic s2_geography[1] with CRS=OGC:CRS84>
#> [1] MULTIPOLYGON (((5.00000004 10.0374231, 3.55739019e-08 10, 3.55739019e-08 3.55739019e-08, 10 3.50334544e-08, 10 5.01900178...
s2_intersection(
"POLYGON ((0 0, 10 0, 10 10, 0 10, 0 0))",
"POLYGON ((5 5, 15 5, 15 15, 5 15, 5 5))",
# 32 bit platforms may need to set snap rounding
s2_options(snap = s2_snap_level(30))
)
#> <geodesic s2_geography[1] with CRS=OGC:CRS84>
#> [1] POLYGON ((5.00000004 4.99999997, 10 5.01900178, 10 9.99999999, 5.00000004 10.0374231, 5.00000004 4.99999997...
s2_union(
"POLYGON ((0 0, 10 0, 10 10, 0 10, 0 0))",
"POLYGON ((5 5, 15 5, 15 15, 5 15, 5 5))",
# 32 bit platforms may need to set snap rounding
s2_options(snap = s2_snap_level(30))
)
#> <geodesic s2_geography[1] with CRS=OGC:CRS84>
#> [1] POLYGON ((5.00000004 10.0374231, 3.55739019e-08 10, 3.55739019e-08 3.55739019e-08, 10 3.50334544e-08, 10 5.01900178...
# s2_convex_hull_agg builds the convex hull of a list of geometries
s2_convex_hull_agg(
c(
"POLYGON ((0 0, 10 0, 10 10, 0 10, 0 0))",
"POLYGON ((5 5, 15 5, 15 15, 5 15, 5 5))"
)
)
#> <geodesic s2_geography[1] with CRS=OGC:CRS84>
#> [1] POLYGON ((0 0, 10 0, 15 5, 15 15, 5 15...
# use s2_union_agg() to aggregate geographies in a vector
s2_coverage_union_agg(
c(
"POLYGON ((0 0, 10 0, 10 10, 0 10, 0 0))",
"POLYGON ((5 5, 15 5, 15 15, 5 15, 5 5))"
),
# 32 bit platforms may need to set snap rounding
s2_options(snap = s2_snap_level(30))
)
#> <geodesic s2_geography[1] with CRS=OGC:CRS84>
#> [1] POLYGON ((5.00000004 10.0374231, 3.55739019e-08 10, 3.55739019e-08 3.55739019e-08, 10 3.50334544e-08, 10 5.01900178...
# snap to grid rounds coordinates to a specified grid size
s2_snap_to_grid("POINT (0.333333333333 0.666666666666)", 1e-2)
#> <geodesic s2_geography[1] with CRS=OGC:CRS84>
#> [1] POINT (0.33 0.67)
```