Better permute[d]dims

Project.toml

@@ -1,7 +1,7 @@
 name = "DiagonalArrays"
 uuid = "74fd4be6-21e2-4f6f-823a-4360d37c7a77"
 authors = ["ITensor developers <[email protected]> and contributors"]
-version = "0.3.12"
+version = "0.3.13"
 
 [deps]
 ArrayLayouts = "4c555306-a7a7-4459-81d9-ec55ddd5c99a"
@@ -12,7 +12,7 @@ SparseArraysBase = "0d5efcca-f356-4864-8770-e1ed8d78f208"
 
 [compat]
 ArrayLayouts = "1.10.4"
-DerivableInterfaces = "0.5"
+DerivableInterfaces = "0.5.5"
 FillArrays = "1.13.0"
 LinearAlgebra = "1.10.0"
 SparseArraysBase = "0.7.2"

src/diagonalarray/diagonalarray.jl

@@ -165,3 +165,20 @@ end
 
 # DiagonalArrays interface.
 diagview(a::DiagonalArray) = a.diag
+
+# Special case for permutedims that is friendlier for immutable storage.
+function Base.permutedims(a::DiagonalArray, perm)
+  ((ndims(a) == length(perm)) && isperm(perm)) ||
+    throw(ArgumentError("Not a valid permutation"))
+  ax_perm = ntuple(d -> axes(a)[perm[d]], ndims(a))
+  # Unlike `permutedims(::Diagonal, perm)`, we copy here.
+  return DiagonalArray(copy(diagview(a)), ax_perm)
+end
+
+function DerivableInterfaces.permuteddims(a::DiagonalArray, perm)
+  ((ndims(a) == length(perm)) && isperm(perm)) ||
+    throw(ArgumentError("Not a valid permutation"))
+  ax_perm = ntuple(d -> axes(a)[perm[d]], ndims(a))
+  # Unlike `permutedims(::Diagonal, perm)`, we copy here.
+  return DiagonalArray(diagview(a), ax_perm)
+end

test/Project.toml

@@ -1,5 +1,6 @@
 [deps]
 Aqua = "4c88cf16-eb10-579e-8560-4a9242c79595"
+DerivableInterfaces = "6c5e35bf-e59e-4898-b73c-732dcc4ba65f"
 DiagonalArrays = "74fd4be6-21e2-4f6f-823a-4360d37c7a77"
 FillArrays = "1a297f60-69ca-5386-bcde-b61e274b549b"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"

test/test_basics.jl

@@ -1,4 +1,5 @@
 using Test: @test, @testset, @test_broken, @inferred
+using DerivableInterfaces: permuteddims
 using DiagonalArrays:
   DiagonalArrays,
   Delta,
@@ -102,6 +103,19 @@ using LinearAlgebra: Diagonal
         eltype(DiagonalArray{elt,2}(undef, Base.OneTo(2), Base.OneTo(2))) ≡
         eltype(DiagonalArray{elt,2}(undef, (Base.OneTo(2), Base.OneTo(2))))
     end
+    @testset "permutedims" begin
+      a = DiagonalArray(randn(elt, 2), (2, 3, 4))
+      b = permutedims(a, (3, 1, 2))
+      @test diagview(b) == diagview(a)
+      @test diagview(b) ≢ diagview(a)
+      @test size(b) === (4, 2, 3)
+    end
+    @testset "DerivableInterfaces.permuteddims" begin
+      a = DiagonalArray(randn(elt, 2), (2, 3, 4))
+      b = permuteddims(a, (3, 1, 2))
+      @test diagview(b) ≡ diagview(a)
+      @test size(b) === (4, 2, 3)
+    end
     @testset "Matrix multiplication" begin
       a1 = DiagonalArray{elt}(undef, (2, 3))
       a1[1, 1] = 11