to_vec on SubArrays and ReshapedArrays

Project.toml

@@ -1,6 +1,6 @@
 name = "FiniteDifferences"
 uuid = "26cc04aa-876d-5657-8c51-4c34ba976000"
-version = "0.11.0"
+version = "0.11.1"
 
 [deps]
 ChainRulesCore = "d360d2e6-b24c-11e9-a2a3-2a2ae2dbcce4"

src/to_vec.jl

@@ -33,7 +33,6 @@ function to_vec(x::AbstractVector)
 end
 
 function to_vec(x::AbstractArray)
-
     x_vec, from_vec = to_vec(vec(x))
 
     function Array_from_vec(x_vec)
@@ -43,7 +42,22 @@ function to_vec(x::AbstractArray)
     return x_vec, Array_from_vec
 end
 
+
 # Some specific subtypes of AbstractArray.
+function to_vec(x::Base.ReshapedArray{<:Any, 1})
+    x_vec, from_vec = to_vec(parent(x))
+    function ReshapedArray_from_vec(x_vec)
+        p = from_vec(x_vec)
+        return Base.ReshapedArray(p, x.dims, x.mi)
+    end
+
+    return x_vec, ReshapedArray_from_vec
+end
+
+# To return a SubArray we would endup needing to copy the `parent` of `x` in `from_vec`
+# which doesn't seem particularly useful. So we just convert the view into a copy.
+# we might be able to do something more performant but this seems good for now.
+to_vec(x::Base.SubArray) = to_vec(copy(x))
 
 function to_vec(x::T) where {T<:LinearAlgebra.AbstractTriangular}
     x_vec, back = to_vec(Matrix(x))

test/to_vec.jl

@@ -50,6 +50,9 @@ end
         test_to_vec(DummyType(randn(T, 2, 9)))
         test_to_vec(SVector{2, T}(1.0, 2.0))
         test_to_vec(SMatrix{2, 2, T}(1.0, 2.0, 3.0, 4.0))
+        test_to_vec(@view randn(T, 10)[1:4])  # SubArray -- Vector
+        test_to_vec(@view randn(T, 10, 2)[1:4, :])  # SubArray -- Matrix
+        test_to_vec(Base.ReshapedArray(rand(T, 3, 3), (9,), ()))
 
         @testset "$Op" for Op in (Symmetric, Hermitian)
             test_to_vec(Op(randn(T, 11, 11)))