Add ishomogeneous trait

Author: juliohm

src/PointPatterns.jl

@@ -25,6 +25,7 @@ export
   PointProcess,
   BinomialProcess,
   PoissonProcess,
-  UnionProcess
+  UnionProcess,
+  ishomogeneous
 
 end # module

src/processes.jl

@@ -9,6 +9,13 @@ A spatial point process.
 """
 abstract type PointProcess end
 
+"""
+    ishomogeneous(p)
+
+Tells whether or not the spatial point process `p` is homogeneous.
+"""
+ishomogeneous(p::PointProcess) = false
+
 """
     rand(p, r, n=1)
 

src/processes/binomial.jl

@@ -11,6 +11,8 @@ struct BinomialProcess <: PointProcess
   n::Int
 end
 
+ishomogeneous(p::BinomialProcess) = true
+
 function rand_single(p::BinomialProcess, r::RectangleRegion{T,N}) where {N,T}
   # region configuration
   lo = lowerleft(r)

src/processes/poisson.jl

@@ -7,18 +7,20 @@
 
 A Poisson process with intensity `λ`.
 """
-struct PoissonProcess{L} <: PointProcess
+struct PoissonProcess{L<:Union{Real,Function}} <: PointProcess
   λ::L
 end
 
-function rand_single(p::PoissonProcess, r::RectangleRegion{T,N}) where {N,T}
+ishomogeneous(p::PoissonProcess{<:Real}) = true
+
+# homogeneous case
+function rand_single(p::PoissonProcess{<:Real}, r::RectangleRegion{T,N}) where {N,T}
   # region configuration
   lo = lowerleft(r)
   up = upperright(r)
 
   # simulate number of points
-  λ = p.λ
-  V = volume(r)
+  λ = p.λ; V = volume(r)
   n = rand(Poisson(λ*V))
 
   # product of uniform distributions
@@ -28,4 +30,9 @@ function rand_single(p::PoissonProcess, r::RectangleRegion{T,N}) where {N,T}
   PointPattern(rand(U, n))
 end
 
+# inhomogeneous case
+function rand_single(p::PoissonProcess{<:Function}, r::RectangleRegion{T,N}) where {N,T}
+  # TODO
+end
+
 Base.union(p₁::PoissonProcess, p₂::PoissonProcess) = PoissonProcess(p₁.λ + p₂.λ)

src/processes/union.jl

@@ -12,6 +12,8 @@ struct UnionProcess{P₁<:PointProcess,P₂<:PointProcess} <: PointProcess
   p₂::P₂
 end
 
+ishomogeneous(p::UnionProcess) = ishomogeneous(p.p₁) && ishomogeneous(p.p₂)
+
 function rand_single(p::UnionProcess, r::AbstractRegion)
   pp₁ = rand(p.p₁, r)
   pp₂ = rand(p.p₂, r)