add area method for VPolygon

JuliaReach · Apr 10, 2023 · ea182bb · ea182bb
1 parent bec1500
commit ea182bb
Show file tree

Hide file tree

Showing 3 changed files with 36 additions and 6 deletions.
diff --git a/docs/src/lib/sets/VPolygon.md b/docs/src/lib/sets/VPolygon.md
@@ -19,7 +19,8 @@ translate!(::VPolygon, ::AbstractVector)
 remove_redundant_vertices(::VPolygon; ::String="monotone_chain")
 remove_redundant_vertices!(::VPolygon; ::String="monotone_chain")
 permute(::VPolygon, ::AbstractVector{Int})
-linear_map(M::AbstractMatrix, P::VPolygon)
+linear_map(::AbstractMatrix, ::VPolygon)
+area(::VPolygon)
 ```
 Inherited from [`LazySet`](@ref):
 * [`norm`](@ref norm(::LazySet, ::Real))

diff --git a/src/Sets/VPolygon.jl b/src/Sets/VPolygon.jl
@@ -711,3 +711,24 @@ The permuted polygon in vertex representation.
 function permute(V::VPolygon, p::AbstractVector{Int})
     return VPolygon([v[p] for v in V.vertices]; apply_convex_hull=true)
 end
+
+"""
+    area(V::VPolygon)
+
+Compute the area of a polygon in vertex representation.
+
+### Input
+
+- `V` -- polygon in vertex representation
+
+### Output
+
+A number representing the area of `V`.
+
+### Algorithm
+
+See [`area(::LazySet)`](@ref).
+"""
+function area(V::VPolygon)
+    return _area_vlist(V.vertices; apply_convex_hull=false)
+end
diff --git a/test/Sets/Polygon.jl b/test/Sets/Polygon.jl
@@ -1,9 +1,4 @@
 for N in [Float64, Float32, Rational{Int}]
-    # random polygons
-    rand(HPolygon)
-    rand(HPolygonOpt)
-    rand(VPolygon)
-
     # Empty polygon
     p = HPolygon{N}()
 
@@ -474,6 +469,14 @@ for N in [Float64, Float32, Rational{Int}]
     @test Z isa VPolygon{N} && ispermutation(vertices_list(Z), vlist)
     Z = minkowski_sum(X + Y, Singleton(zeros(N, 2)))
     @test Z isa VPolygon{N} && ispermutation(vertices_list(Z), vlist)
+
+    # area
+    v1 = N[1, 3]
+    v2 = N[2, 1]
+    v3 = N[4, 6]
+    v4 = N[9, 2]
+    P = VPolygon([v1, v2, v3, v4])
+    @test area(P) == N(21)
 end
 
 for N in [Float64, Float32]
@@ -654,6 +657,11 @@ for N in [Float64]
     @test isa(Pr, HPolygon{Rational{BigInt}, Vector{Rational{BigInt}}})
 end
 
+# random polygons
+rand(HPolygon)
+rand(HPolygonOpt)
+rand(VPolygon)
+
 # default Float64 constructors
 @test HPolygon() isa HPolygon{Float64, Vector{Float64}}
 @test HPolygonOpt() isa HPolygonOpt{Float64, Vector{Float64}}