Avoid allocations in vertex of PolyArea (#1135)

* Avoid allocations in 'vertex' of 'PolyArea'

* Update 'vertextest'

* Update src/geometries/polytopes/polyarea.jl

Co-authored-by: Júlio Hoffimann <[email protected]>

* Update 'vertices' of 'PolyArea'

---------

Co-authored-by: Júlio Hoffimann <[email protected]>

Author: eliascarv

src/geometries/polytopes/polyarea.jl

@@ -31,7 +31,19 @@ PolyArea(outer...) = PolyArea(collect(outer))
 Base.isapprox(p₁::PolyArea, p₂::PolyArea; atol=atol(lentype(p₁)), kwargs...) =
   length(p₁.rings) == length(p₂.rings) && all(isapprox(r₁, r₂; atol, kwargs...) for (r₁, r₂) in zip(p₁.rings, p₂.rings))
 
-vertices(p::PolyArea) = mapreduce(vertices, vcat, p.rings)
+function vertex(p::PolyArea, ind)
+  offset = 0
+  for r in p.rings
+    nverts = nvertices(r)
+    if ind ≤ offset + nverts
+      return vertex(r, ind - offset)
+    end
+    offset += nverts
+  end
+  throw(BoundsError(p, ind))
+end
+
+vertices(p::PolyArea) = collect(eachvertex(p))
 
 nvertices(p::PolyArea) = mapreduce(nvertices, +, p.rings)
 

test/multigeoms.jl

@@ -112,5 +112,5 @@
   multi3 = Multi([poly3, poly4])
   vertextest(multi1)
   vertextest(multi2)
-  vertextest(multi3, bytes=3100)
+  vertextest(multi3)
 end

test/polytopes.jl

@@ -652,9 +652,27 @@ end
   @test centroid(poly) == cart(0.5, 0.5)
 
   # single vertex access
-  poly = PolyArea(cart.([(0, 0), (1, 0), (1, 1), (0, 1)]))
+  outer = cart.([(0, 0), (1, 0), (1, 1), (0, 1)])
+  hole1 = cart.([(0.2, 0.2), (0.4, 0.2), (0.4, 0.4), (0.2, 0.4)])
+  hole2 = cart.([(0.6, 0.2), (0.8, 0.2), (0.8, 0.4), (0.6, 0.4)])
+  poly = PolyArea([outer, hole1, hole2])
   @test vertex(poly, 1) == cart(0, 0)
+  @test vertex(poly, 2) == cart(1, 0)
+  @test vertex(poly, 3) == cart(1, 1)
   @test vertex(poly, 4) == cart(0, 1)
+  @test vertex(poly, 5) == cart(0.2, 0.2)
+  @test vertex(poly, 6) == cart(0.4, 0.2)
+  @test vertex(poly, 7) == cart(0.4, 0.4)
+  @test vertex(poly, 8) == cart(0.2, 0.4)
+  @test vertex(poly, 9) == cart(0.6, 0.2)
+  @test vertex(poly, 10) == cart(0.8, 0.2)
+  @test vertex(poly, 11) == cart(0.8, 0.4)
+  @test vertex(poly, 12) == cart(0.6, 0.4)
+  @test_throws BoundsError vertex(poly, 13)
+  # type stability
+  @inferred vertex(poly, 4)
+  @inferred vertex(poly, 8)
+  @inferred vertex(poly, 12)
 
   # point in polygonal area
   outer = cart.([(0, 0), (1, 0), (1, 1), (0, 1)])

test/testutils.jl

@@ -183,9 +183,9 @@ function eachvertexalloc(g)
   end
 end
 
-function vertextest(g; bytes=0)
+function vertextest(g)
   @test collect(eachvertex(g)) == vertices(g)
-  @test eachvertexalloc(g) ≤ bytes
+  @test eachvertexalloc(g) == 0
   # type stability
   @test isconcretetype(eltype(vertices(g)))
   @inferred vertices(g)