Build multilinestrings from coordinate columns

Returns one multilinestring per run of multilinestring_id, with one line per run of linestring_id inside it.

Usage

ga_multilinestring(
  x,
  y,
  z = NULL,
  m = NULL,
  multilinestring_id = NULL,
  linestring_id = NULL,
  crs = NULL
)

Arguments

x, y

numeric vectors or float64 arrays of coordinates, one row per vertex

z, m

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

multilinestring_id

a numeric vector, character vector, or Arrow array naming the multilinestring of each row, or NULL for a single multilinestring

linestring_id

a numeric vector, character vector, or Arrow array naming the line of each row within its multilinestring, or NULL for one line per multilinestring

crs

a coordinate reference system to record, or NULL for none

Value

a GeoArrow multilinestring array with one element per multilinestring

Details

ga_multilinestring() matches sfheaders::sf_multilinestring(), taking the columns themselves rather than a data frame and their names. You must keep the rows of each multilinestring together: ga_multilinestring() errors when a multilinestring_id returns after a different one, and orders the multilinestrings by where each id first appears. It starts a new line at the start of each multilinestring and wherever linestring_id changes, so you can number the lines of every multilinestring from 1.

ga_multilinestring() adds the z and m dimensions when you supply z and m. It errors on NA in any coordinate or id, and reuses the coordinate arrays without copying them.

See also

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

Examples

lines <- ga_multilinestring(
  c(0, 1, 5, 6, 10, 11),
  c(0, 1, 5, 6, 0, 1),
  multilinestring_id = c(1, 1, 1, 1, 2, 2),
  linestring_id = c(1, 1, 2, 2, 1, 1)
)
sf::st_as_sfc(geoarrow::as_geoarrow_vctr(lines))
#> Geometry set for 2 features 
#> Geometry type: MULTILINESTRING
#> Dimension:     XY
#> Bounding box:  xmin: 0 ymin: 0 xmax: 11 ymax: 6
#> CRS:           NA
#> MULTILINESTRING ((0 0, 1 1), (5 5, 6 6))
#> MULTILINESTRING ((10 0, 11 1))