Fixed DiffEqArray constructors, added tests

- DiffEqArray constructs SymbolCache taking into account if `indepsym` is
  `nothing`, a single symbol or an `AbstractArray` of symbols
- Test symbolic indexing functionality

Author: AayushSabharwal

src/vector_of_array.jl

@@ -93,11 +93,23 @@ VectorOfArray(vec::AbstractVector{T}, ::NTuple{N}) where {T, N} = VectorOfArray{
 VectorOfArray(vec::AbstractVector) = VectorOfArray(vec, (size(vec[1])..., length(vec)))
 VectorOfArray(vec::AbstractVector{VT}) where {T, N, VT<:AbstractArray{T, N}} = VectorOfArray{T, N+1, typeof(vec)}(vec)
 
-DiffEqArray(vec::AbstractVector{T}, ts, ::NTuple{N}, syms=nothing, indepsym=nothing, observed=nothing, p=nothing) where {T, N} = DiffEqArray{eltype(T), N, typeof(vec), typeof(ts), SymbolCache{typeof(syms), Vector{typeof(indepsym)}, Nothing}, typeof(observed), typeof(p)}(vec, ts, SymbolCache(syms, [indepsym], nothing), observed, p)
+function DiffEqArray(vec::AbstractVector{T}, ts, ::NTuple{N}, syms=nothing, indepsym=nothing, observed=nothing, p=nothing) where {T, N}
+  sc = if isnothing(indepsym) || indepsym isa AbstractArray
+    SymbolCache{typeof(syms),typeof(indepsym),Nothing}(syms, indepsym, nothing)
+  else
+    SymbolCache{typeof(syms),Vector{typeof(indepsym)},Nothing}(syms, [indepsym], nothing)
+  end
+  DiffEqArray{eltype(T), N, typeof(vec), typeof(ts), typeof(sc), typeof(observed), typeof(p)}(vec, ts, sc, observed, p)
+end
 # Assume that the first element is representative of all other elements
 DiffEqArray(vec::AbstractVector,ts::AbstractVector, syms=nothing, indepsym=nothing, observed=nothing, p=nothing) = DiffEqArray(vec, ts, (size(vec[1])..., length(vec)), syms, indepsym, observed, p)
 function DiffEqArray(vec::AbstractVector{VT},ts::AbstractVector, syms=nothing, indepsym=nothing, observed=nothing, p=nothing) where {T, N, VT<:AbstractArray{T, N}}
-  DiffEqArray{T, N+1, typeof(vec), typeof(ts), SymbolCache{typeof(syms), Vector{typeof(indepsym)}, Nothing}, typeof(observed), typeof(p)}(vec, ts, SymbolCache(syms, [indepsym], nothing), observed, p)
+  sc = if isnothing(indepsym) || indepsym isa AbstractArray
+    SymbolCache{typeof(syms),typeof(indepsym),Nothing}(syms, indepsym, nothing)
+  else
+    SymbolCache{typeof(syms),Vector{typeof(indepsym)},Nothing}(syms, [indepsym], nothing)
+  end
+  DiffEqArray{T, N+1, typeof(vec), typeof(ts), typeof(sc), typeof(observed), typeof(p)}(vec, ts, sc, observed, p)
 end
 
 # Interface for the linear indexing. This is just a view of the underlying nested structure

test/symbolic_indexing_interface_test.jl

@@ -26,3 +26,17 @@ sc = SymbolCache([:a, :b], [:t], [:c, :d])
 @test isnothing(param_sym_to_index(sc, :a))
 @test all(is_param_sym.((sc,), [:c, :d]))
 @test !is_param_sym(sc, :b)
+
+t = 0.0:0.1:1.0
+f(x) = 2x
+f2(x) = 3x
+
+dx = DiffEqArray([[f(x), f2(x)] for x in t], t, [:a, :b], :t)
+@test dx[:t] == t
+@test dx[:a] == [f(x) for x in t]
+@test dx[:b] == [f2(x) for x in t]
+
+dx = DiffEqArray([[f(x), f2(x)] for x in t], t, [:a, :b], [:t])
+@test dx[:t] == t
+dx = DiffEqArray([[f(x), f2(x)] for x in t], t, [:a, :b])
+@test_throws Exception dx[nothing] # make sure it isn't storing [nothing] as indepsym