More convenient cartesianrange constructor

Project.toml

@@ -1,7 +1,7 @@
 name = "KroneckerArrays"
 uuid = "05d0b138-81bc-4ff7-84be-08becefb1ccc"
 authors = ["ITensor developers <[email protected]> and contributors"]
-version = "0.1.7"
+version = "0.1.8"
 
 [deps]
 DerivableInterfaces = "6c5e35bf-e59e-4898-b73c-732dcc4ba65f"

src/KroneckerArrays.jl

@@ -35,6 +35,27 @@ end
 Base.first(r::CartesianProductUnitRange) = first(r.range)
 Base.last(r::CartesianProductUnitRange) = last(r.range)
 
+cartesianproduct(r::CartesianProductUnitRange) = getfield(r, :product)
+unproduct(r::CartesianProductUnitRange) = getfield(r, :range)
+
+function CartesianProductUnitRange(p::CartesianProduct)
+  return CartesianProductUnitRange(p, Base.OneTo(length(p)))
+end
+function CartesianProductUnitRange(a, b)
+  return CartesianProductUnitRange(a × b)
+end
+to_range(a::AbstractUnitRange) = a
+to_range(i::Integer) = Base.OneTo(i)
+cartesianrange(a, b) = cartesianrange(to_range(a) × to_range(b))
+function cartesianrange(p::CartesianProduct)
+  p′ = to_range(p.a) × to_range(p.b)
+  return cartesianrange(p′, Base.OneTo(length(p′)))
+end
+function cartesianrange(p::CartesianProduct, range::AbstractUnitRange)
+  p′ = to_range(p.a) × to_range(p.b)
+  return CartesianProductUnitRange(p′, range)
+end
+
 function Base.axes(r::CartesianProductUnitRange)
   return (CartesianProductUnitRange(r.product, only(axes(r.range))),)
 end

test/test_basics.jl

@@ -1,5 +1,14 @@
 using FillArrays: Eye
-using KroneckerArrays: KroneckerArrays, ⊗, ×, diagonal, kron_nd
+using KroneckerArrays:
+  KroneckerArrays,
+  CartesianProductUnitRange,
+  ⊗,
+  ×,
+  cartesianproduct,
+  cartesianrange,
+  diagonal,
+  kron_nd,
+  unproduct
 using LinearAlgebra: Diagonal, I, det, eigen, eigvals, lq, pinv, qr, svd, svdvals, tr
 using StableRNGs: StableRNG
 using Test: @test, @test_broken, @test_throws, @testset
@@ -10,6 +19,25 @@ const elts = (Float32, Float64, ComplexF32, ComplexF64)
   @test length(p) == 6
   @test collect(p) == [1 × 3, 2 × 3, 1 × 4, 2 × 4, 1 × 5, 2 × 5]
 
+  r = cartesianrange(2, 3)
+  @test r ===
+    cartesianrange(2 × 3) ===
+    cartesianrange(Base.OneTo(2), Base.OneTo(3)) ===
+    cartesianrange(Base.OneTo(2) × Base.OneTo(3))
+  @test cartesianproduct(r) === Base.OneTo(2) × Base.OneTo(3)
+  @test unproduct(r) === Base.OneTo(6)
+  @test length(r) == 6
+  @test first(r) == 1
+  @test last(r) == 6
+
+  r = cartesianrange(2 × 3, 2:7)
+  @test r === cartesianrange(Base.OneTo(2) × Base.OneTo(3), 2:7)
+  @test cartesianproduct(r) === Base.OneTo(2) × Base.OneTo(3)
+  @test unproduct(r) === 2:7
+  @test length(r) == 6
+  @test first(r) == 2
+  @test last(r) == 7
+
   a = randn(elt, 2, 2) ⊗ randn(elt, 3, 3)
   b = randn(elt, 2, 2) ⊗ randn(elt, 3, 3)
   c = a.a ⊗ b.b