address possibility of different encodings for summands

Author: ablaom

src/arithmetic.jl

@@ -6,19 +6,14 @@ const ERR_DIFFERENT_SAMPLE_SPACES = ArgumentError(
 
 import Base: +, *, /, -
 
-function _plus(d1, d2, T)
-    classes(d1) == classes(d2) || throw(ERR_DIFFERENT_SAMPLE_SPACES)
-    S = d1.scitype
-    decoder = d1.decoder
-    prob_given_ref = copy(d1.prob_given_ref)
-    for ref in keys(prob_given_ref)
-        prob_given_ref[ref] += d2.prob_given_ref[ref]
-    end
-    return T(S, decoder, prob_given_ref)
+pdf_matrix(d::UnivariateFinite, L) = pdf.(d, L)
+pdf_matrix(d::AbstractArray{<:UnivariateFinite}, L) = pdf(d, L)
+
+function +(d1::U, d2::U) where U <: SingletonOrArray
+    L = classes(d1)
+    L == classes(d2) || throw(ERR_DIFFERENT_SAMPLE_SPACES)
+    return UnivariateFinite(L, pdf_matrix(d1, L) + pdf_matrix(d2, L))
 end
-+(d1::U, d2::U) where U <: UnivariateFinite = _plus(d1, d2, UnivariateFinite)
-+(d1::U, d2::U) where U <: UnivariateFiniteArray =
-    _plus(d1, d2, UnivariateFiniteArray)
 
 function _minus(d, T)
     S = d.scitype
@@ -32,19 +27,11 @@ end
 -(d::UnivariateFinite) = _minus(d, UnivariateFinite)
 -(d::UnivariateFiniteArray) = _minus(d, UnivariateFiniteArray)
 
-function _minus(d1, d2, T)
-    classes(d1) == classes(d2) || throw(ERR_DIFFERENT_SAMPLE_SPACES)
-    S = d1.scitype
-    decoder = d1.decoder
-    prob_given_ref = copy(d1.prob_given_ref)
-    for ref in keys(prob_given_ref)
-        prob_given_ref[ref] -= d2.prob_given_ref[ref]
-    end
-    return T(S, decoder, prob_given_ref)
+function -(d1::U, d2::U) where U <: SingletonOrArray
+    L = classes(d1)
+    L == classes(d2) || throw(ERR_DIFFERENT_SAMPLE_SPACES)
+    return UnivariateFinite(L, pdf_matrix(d1, L) - pdf_matrix(d2, L))
 end
--(d1::U, d2::U) where U <: UnivariateFinite = _minus(d1, d2, UnivariateFinite)
--(d1::U, d2::U) where U <: UnivariateFiniteArray =
-    _minus(d1, d2, UnivariateFiniteArray)
 
 # It seems that the restriction `x::Number` below (applying only to the
 # array case) is unavoidable because of a method ambiguity with

test/arithmetic.jl

@@ -39,9 +39,9 @@ d2 = UnivariateFinite(L, rand(rng, 2), pool=missing)
 end
 
 p = [0.1, 0.9]
-P = vcat(fill(p', 10^5)...)
-slow = fill(UnivariateFinite(L, p, pool=missing), 10^5)
-fast = UnivariateFinite(L, P, pool=missing)
+P = vcat(fill(p', 10^5)...);
+slow = fill(UnivariateFinite(L, p, pool=missing), 10^5);
+fast = UnivariateFinite(L, P, pool=missing);
 # @assert pdf(slow, L) == pdf(fast, L)
 
 @testset "performant arithmetic for UnivariateFiniteArray" begin