Test whether a ring is convex

TRUE when the geometry's ring turns consistently in one direction. A polygon is judged on its exterior ring.

Usage

ga_is_convex(geometry)

Arguments

geometry

a GeoArrow linestring or polygon array

Value

a boolean array of the same length as geometry

Details

A linestring must be closed, that is form a ring, to be reported convex; an open one is FALSE. A polygon's exterior ring is always closed, so polygons need no special handling. Any other geometry type, or a null geometry, becomes NA rather than FALSE.

References

IsConvex

See also

Other query: ga_closest_point(), ga_interior_point(), ga_line_locate_point()

Examples

square <- sf::st_polygon(list(
  matrix(c(0, 0, 1, 0, 1, 1, 0, 1, 0, 0), ncol = 2, byrow = TRUE)
))
g <- geoarrow::as_geoarrow_array(sf::st_sfc(square))

as.vector(ga_is_convex(g))
#> [1] TRUE