Merge pull request #46 from SciML/restructure

add restructure

Author: ChrisRackauckas

Project.toml

@@ -1,6 +1,6 @@
 name = "ArrayInterface"
 uuid = "4fba245c-0d91-5ea0-9b3e-6abc04ee57a9"
-version = "2.7.0"
+version = "2.8.0"
 
 [deps]
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"

README.md

@@ -75,7 +75,7 @@ Is a form of `vec` which is safe for all values in vector spaces, i.e. if
 is already a vector, like an AbstractVector or Number, it will return said
 AbstractVector or Number.
 
-## zeromatrix(u::AbstractVector)
+## zeromatrix(u)
 
 Creates the zero'd matrix version of `u`. Note that this is unique because
 `similar(u,length(u),length(u))` returns a mutable type, so is not type-matching,
@@ -85,15 +85,24 @@ i.e. you'll get a CPU array from a GPU array. The generic fallback is
 with weird (recursive) broadcast overloads. For higher order tensors, this
 returns the matrix linear operator type which acts on the `vec` of the array.
 
-## List of things to add
+## restructure(x,y)
+
+Restructures the object `y` into a shape of `x`, keeping its values intact. For
+simple objects like an `Array`, this simply amounts to a reshape. However, for
+more complex objects such as an `ArrayPartition`, not all of the structural
+information is adequately contained in the type for standard tools to work. In
+these cases, `restructure` gives a way to convert for example an `Array` into
+a matching `ArrayPartition`.
+
+# List of things to add
 
 - https://github.com/JuliaLang/julia/issues/22216
 - https://github.com/JuliaLang/julia/issues/22218
 - https://github.com/JuliaLang/julia/issues/22622
 - https://github.com/JuliaLang/julia/issues/25760
 - https://github.com/JuliaLang/julia/issues/25107
 
-## Array Types to Handle
+# Array Types to Handle
 
 The following common array types are being understood and tested as part of this
 development.

src/ArrayInterface.jl

@@ -447,6 +447,25 @@ function zeromatrix(u)
   x .* x' .* false
 end
 
+"""
+restructure(x,y)
+
+Restructures the object `y` into a shape of `x`, keeping its values intact. For
+simple objects like an `Array`, this simply amounts to a reshape. However, for
+more complex objects such as an `ArrayPartition`, not all of the structural
+information is adequately contained in the type for standard tools to work. In
+these cases, `restructure` gives a way to convert for example an `Array` into
+a matching `ArrayPartition`.
+"""
+function restructure(x,y)
+  out = similar(x,eltype(y))
+  out .= y
+end
+
+function restructure(x::Array,y)
+  reshape(convert(Array,y),size(x)...)
+end
+
 function __init__()
 
   @require SuiteSparse="4607b0f0-06f3-5cda-b6b1-a6196a1729e9" begin
@@ -461,13 +480,18 @@ function __init__()
     ismutable(::Type{<:StaticArrays.StaticArray}) = false
     can_setindex(::Type{<:StaticArrays.StaticArray}) = false
     ismutable(::Type{<:StaticArrays.MArray}) = true
+
     function lu_instance(_A::StaticArrays.StaticMatrix{N,N}) where {N}
       A = StaticArrays.SArray(_A)
       L = LowerTriangular(A)
       U = UpperTriangular(A)
       p = StaticArrays.SVector{N,Int}(1:N)
       return StaticArrays.LU(L, U, p)
     end
+
+    function restructure(x::StaticArrays.SArray,y)
+      error("Currently not supported")
+    end
   end
 
   @require LabelledArrays="2ee39098-c373-598a-b85f-a56591580800" begin
@@ -483,7 +507,9 @@ function __init__()
   end
 
   @require CuArrays="3a865a2d-5b23-5a0f-bc46-62713ec82fae" begin
-    include("cuarrays.jl")
+    @require Adapt="79e6a3ab-5dfb-504d-930d-738a2a938a0e" begin
+      include("cuarrays.jl")
+    end
   end
 
   @require BandedMatrices="aae01518-5342-5314-be14-df237901396f" begin

src/cuarrays.jl

@@ -7,3 +7,7 @@ function Base.setindex(x::CuArrays.CuArray,v,i::Int)
   allowed_setindex!(_x,v,i)
   _x
 end
+
+function restructure(x::CuArrays,y)
+  reshape(adapt(typeof(x),y),size(x)...)
+end