tests/testthat/test-poi-sf.R

In polylabelr: Find the Pole of Inaccessibility (Visual Center) of a Polygon

test_that("poi works with simple features", {
  skip_if_not_installed('sf')
  library(sf)

  # Create some test objects
  p <- st_point(c(1,2))
  pts <- rbind(c(3.2,4), c(3,4.6), c(3.8,4.4), c(3.5,3.8), c(3.4,3.6), c(3.9,4.5))
  mp <- st_multipoint(pts)
  ## MULTIPOINT ((3.2 4), (3 4.6), (3.8 4.4), (3.5 3.8), (3.4 3.6), (3.9 4.5))

  s1 <- rbind(c(0,3),c(0,4),c(1,5),c(2,5))
  ls <- st_linestring(s1)
  ## LINESTRING (0 3, 0 4, 1 5, 2 5)

  s2 <- rbind(c(0.2,3), c(0.2,4), c(1,4.8), c(2,4.8))
  s3 <- rbind(c(0,4.4), c(0.6,5))
  mls <- st_multilinestring(list(s1,s2,s3))
  ## MULTILINESTRING ((0 3, 0 4, 1 5, 2 5), (0.2 3, 0.2 4, 1 4.8, 2 4.8), (0 4.4, 0.6 5))

  p1 <- rbind(c(0,0), c(1,0), c(3,2), c(2,4), c(1,4), c(0,0))
  p2 <- rbind(c(1,1), c(1,2), c(2,2), c(1,1))
  pol <-st_polygon(list(p1,p2))
  # POLYGON ((0 0, 1 0, 3 2, 2 4, 1 4, 0 0), (1 1, 1 2, 2 2, 1 1))

  p3 <- rbind(c(3,0), c(4,0), c(4,1), c(3,1), c(3,0))
  p4 <- rbind(c(3.3,0.3), c(3.8,0.3), c(3.8,0.8), c(3.3,0.8), c(3.3,0.3))[5:1,]
  p5 <- rbind(c(3,3), c(4,2), c(4,3), c(3,3))
  mpol <- st_multipolygon(list(list(p1,p2), list(p3,p4), list(p5)))
  ## MULTIPOLYGON (((0 0, 1 0, 3 2, 2 4, 1 4, 0 0), (1 1, 1 2, 2 2, 1 1)), ((3 0, 4 0, 4 1, 3 1, 3 0), (3.3 0.3, 3.3 0.8, 3.8 0.8, 3.8 0.3, 3.3 0.3)), ((3 3, 4 2, 4 3, 3 3)))

  gc <- st_geometrycollection(list(mp, mpol, ls))

  # These return the first point in the geometry
  expect_equal(poi(p), list(x=1, y=2, dist=0))
  expect_equal(poi(mp), list(x=3.2, y=4, dist=0))
  expect_equal(poi(ls), list(x=0, y=3, dist=0))
  expect_equal(poi(mls), list(x=0, y=3, dist=0))

  # They ignore precision
  expect_equal(poi(p, precision=0.1), list(x=1, y=2, dist=0))
  expect_equal(poi(mp, precision=0.1), list(x=3.2, y=4, dist=0))
  expect_equal(poi(ls, precision=0.1), list(x=0, y=3, dist=0))
  expect_equal(poi(mls, precision=0.1), list(x=0, y=3, dist=0))

  lo_res_poi = list(x=1.875, y=2.625, dist=0.625)
  hi_res_poi = list(x=1.59375, y=2.90625, dist=0.84129)

  expect_equal(poi(pol), lo_res_poi)
  expect_equal(poi(pol, precision=0.1), hi_res_poi, tolerance=0.00001)
  expect_equal(poi(mpol), lo_res_poi)
  expect_equal(poi(mpol, precision=0.1), hi_res_poi, tolerance=0.00001)
  expect_equal(poi(gc), lo_res_poi)
  expect_equal(poi(gc, precision=0.1), hi_res_poi, tolerance=0.00001)
  expect_silent(poi(gc))
})