Build a point array from x and y coordinates

Pairs two numeric vectors into a GeoArrow point array. The shorter of the two is recycled when it is length 1.

Usage

ga_xy(x, y, crs = NULL)

Arguments

x

a numeric vector or float64 array of x coordinates

y

a numeric vector or float64 array of y coordinates; length 1 or the same length as x

crs

a coordinate reference system to record, or NULL for none

Value

a GeoArrow point array

Details

A row where either coordinate is NA gives a null point rather than a point at an arbitrary location, so the result always has the same length as the longer input.

crs is stored verbatim in the array's GeoArrow metadata and is never interpreted, so nothing here reprojects. Anything a reader would produce works, whether an authority code such as "EPSG:4326", WKT, or PROJJSON. Leaving it NULL produces an array with no CRS.

See also

Other construct: ga_make_line()

Examples

pts <- ga_xy(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)

# a length 1 coordinate is recycled
sf::st_as_sfc(geoarrow::as_geoarrow_vctr(ga_xy(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)

# NA in either coordinate gives a null point
ga_xy(c(0, NA), c(0, 1))$null_count
#> [1] 1