Add UnionProcess

Author: juliohm

src/PointPatterns.jl

@@ -24,6 +24,7 @@ export
   # point processes
   PointProcess,
   BinomialProcess,
-  PoissonProcess
+  PoissonProcess,
+  UnionProcess
 
 end # module

src/processes.jl

@@ -20,8 +20,24 @@ Base.rand(p::PointProcess, r::AbstractRegion, n::Int) =
 
 Base.rand(p::PointProcess, r::AbstractRegion) = rand_single(p, r)
 
+"""
+    rand_single(p, r)
+
+Generate a single realization of spatial point process
+`p` inside spatial region `r`.
+"""
+rand_single(p::PointProcess, r::AbstractRegion) = @error "not implemented"
+
+"""
+    p₁ ∪ p₂
+
+Union (or superposition) of spatial point processes `p₁` and `p₂`.
+"""
+Base.union(p₁::PointProcess, p₂::PointProcess) = UnionProcess(p₁, p₂)
+
 #-----------------
 # IMPLEMENTATIONS
 #-----------------
 include("processes/binomial.jl")
 include("processes/poisson.jl")
+include("processes/union.jl")

src/processes/union.jl

@@ -0,0 +1,23 @@
+# ------------------------------------------------------------------
+# Licensed under the ISC License. See LICENSE in the project root.
+# ------------------------------------------------------------------
+
+"""
+    UnionProcess(p₁, p₂)
+
+Union (or superposition) of spatial point processes `p₁` and `p₂`.
+"""
+struct UnionProcess{P₁<:PointProcess,P₂<:PointProcess} <: PointProcess
+  p₁::P₁
+  p₂::P₂
+end
+
+function rand_single(p::UnionProcess, r::AbstractRegion)
+  pp₁ = rand(p.p₁, r)
+  pp₂ = rand(p.p₂, r)
+
+  X = coordinates(pp₁)
+  Y = coordinates(pp₂)
+
+  PointPattern(hcat(X, Y))
+end