geod function

liblwgeom geodetic functions

liblwgeom geodetic functions

liblwgeom geodetic functions for length, area, segmentizing, covers

st_geod_area(x) st_geod_length(x) st_geod_segmentize(x, max_seg_length) st_geod_covers(x, y, sparse = TRUE) st_geod_covered_by(x, y, sparse = TRUE) st_geod_distance(x, y, tolerance = 0, sparse = FALSE)

Arguments

  • x: object of class sf, sfc or sfg
  • max_seg_length: segment length in degree, radians, or as a length unit (e.g., m)
  • y: object of class sf, sfc or sfg
  • sparse: logical; if TRUE, return a sparse matrix (object of class sgbp), otherwise, return a dense logical matrix.
  • tolerance: double or length units value: if positive, the first distance less than tolerance is returned, rather than the true distance

Details

st_area will give an error message when the area spans the equator and lwgeom is linked to a proj.4 version older than 4.9.0 (see lwgeom_extSoftVersion )

longitude coordinates returned are rescaled to [-180,180)

Note

this function should is used by st_distance , do not use it directly

Examples

library(sf) nc = st_read(system.file("gpkg/nc.gpkg", package="sf")) st_geod_area(nc[1:3,]) # st_area(nc[1:3,]) l = st_sfc(st_linestring(rbind(c(7,52), c(8,53))), crs = 4326) st_geod_length(l) library(units) pol = st_polygon(list(rbind(c(0,0), c(0,60), c(60,60), c(0,0)))) x = st_sfc(pol, crs = 4326) seg = st_geod_segmentize(x[1], set_units(10, km)) plot(seg, graticule = TRUE, axes = TRUE) pole = st_polygon(list(rbind(c(0,80), c(120,80), c(240,80), c(0,80)))) pt = st_point(c(0,90)) x = st_sfc(pole, pt, crs = 4326) st_geod_covers(x[c(1,1,1)], x[c(2,2,2,2)]) pole = st_polygon(list(rbind(c(0,80), c(120,80), c(240,80), c(0,80)))) pt = st_point(c(30,70)) x = st_sfc(pole, pt, crs = 4326) st_geod_distance(x, x)