Test whether a ring is convex

TRUE when the geometry's ring turns consistently in one direction. ga_is_convex() judges a polygon 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

ga_is_convex() reports a linestring as convex only when it is closed, that is forms a ring, and returns FALSE for an open one. A polygon's exterior ring is always closed, so ga_is_convex() needs no special case for them. ga_is_convex() returns NA rather than FALSE for any other geometry type or a null geometry.

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