Build a point array from coordinates

Pairs numeric vectors of coordinates into a GeoArrow point array, adding the z and m dimensions when you supply z and m. ga_point() recycles any coordinate of length 1.

Usage

ga_point(x, y, z = NULL, m = NULL, crs = NULL)

Arguments

x, y

numeric vectors or float64 arrays of x and y coordinates; each length 1 or the same length as the longest coordinate

z, m

numeric vectors or float64 arrays of z and m values, or NULL to leave out that dimension

crs

a coordinate reference system to record, or NULL for none

Value

a GeoArrow point array

Details

ga_point() returns a null point for a row where any coordinate is NA, rather than a point at an arbitrary location, so the result always has the same length as the longest input. When every coordinate is full length and has no NA, it reuses the arrays without copying them.

ga_point() stores crs verbatim in the array's GeoArrow metadata and never interprets it, so it never reprojects. It accepts anything a reader would produce, whether an authority code such as "EPSG:4326", WKT, or PROJJSON. If you leave it NULL, ga_point() produces an array with no CRS.

See also

Other construct: ga_linestring(), ga_make_envelope(), ga_make_grid(), ga_make_line(), ga_make_line_agg(), ga_make_polygon(), ga_multilinestring(), ga_multipoint(), ga_multipolygon(), ga_polygon()

Examples

pts <- ga_point(c(0, 1, 2), c(0, 1, 4), crs = "EPSG:4326")
sf::st_as_sfc(geoarrow::as_geoarrow_vctr(pts))
#> Geometry set for 3 features 
#> Geometry type: POINT
#> Dimension:     XY
#> Bounding box:  xmin: 0 ymin: 0 xmax: 2 ymax: 4
#> Geodetic CRS:  WGS 84
#> POINT (0 0)
#> POINT (1 1)
#> POINT (2 4)

# ga_point() recycles a length 1 coordinate
sf::st_as_sfc(geoarrow::as_geoarrow_vctr(ga_point(c(0, 1, 2), 0)))
#> Geometry set for 3 features 
#> Geometry type: POINT
#> Dimension:     XY
#> Bounding box:  xmin: 0 ymin: 0 xmax: 2 ymax: 0
#> CRS:           NA
#> POINT (0 0)
#> POINT (1 0)
#> POINT (2 0)

# supplying z gives a POINT Z
sf::st_as_sfc(geoarrow::as_geoarrow_vctr(ga_point(c(0, 1), c(0, 1), z = c(5, 6))))
#> Geometry set for 2 features 
#> Geometry type: POINT
#> Dimension:     XYZ
#> Bounding box:  xmin: 0 ymin: 0 xmax: 1 ymax: 1
#> z_range:       zmin: 5 zmax: 6
#> CRS:           NA
#> POINT Z (0 0 5)
#> POINT Z (1 1 6)

# ga_point() returns a null point for NA in any coordinate
ga_point(c(0, NA), c(0, 1))$null_count
#> [1] 1