Add diagonal as a generalization of LinearAlgebra.Diagonal

Project.toml

@@ -1,15 +1,17 @@
 name = "DiagonalArrays"
 uuid = "74fd4be6-21e2-4f6f-823a-4360d37c7a77"
 authors = ["ITensor developers <[email protected]> and contributors"]
-version = "0.2.1"
+version = "0.2.2"
 
 [deps]
 ArrayLayouts = "4c555306-a7a7-4459-81d9-ec55ddd5c99a"
 DerivableInterfaces = "6c5e35bf-e59e-4898-b73c-732dcc4ba65f"
+LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 SparseArraysBase = "0d5efcca-f356-4864-8770-e1ed8d78f208"
 
 [compat]
 ArrayLayouts = "1.10.4"
 DerivableInterfaces = "0.3.7"
+LinearAlgebra = "1.10.0"
 SparseArraysBase = "0.2.1"
 julia = "1.10"

docs/make.jl

@@ -14,7 +14,7 @@ makedocs(;
     edit_link="main",
     assets=String[],
   ),
-  pages=["Home" => "index.md"],
+  pages=["Home" => "index.md", "Library" => "library.md"],
 )
 
 deploydocs(;

docs/src/library.md

@@ -0,0 +1,5 @@
+# Library
+
+```@autodocs
+Modules = [DiagonalArrays]
+```

src/diaginterface/diaginterface.jl

@@ -1,5 +1,7 @@
 # TODO: Turn these into `@interface ::AbstractDiagonalArrayInterface` functions.
 
+using LinearAlgebra: LinearAlgebra
+
 diaglength(a::AbstractArray{<:Any,0}) = 1
 
 function diaglength(a::AbstractArray)
@@ -88,3 +90,21 @@ function setdiagindices!(a::AbstractArray, v, i::Colon)
   diagview(a) .= v
   return a
 end
+
+"""
+    diagonal(v::AbstractVector, [axes]) -> AbstractMatrix
+
+Return a diagonal matrix from a vector `v`, optionally providing the `axes` of the resulting matrix.
+This is an extension of `LinearAlgebra.Diagonal`, designed to avoid the implication of the output type,
+as well as allowing the option of specifying the `axes`.
+Defaults to `Diagonal(v)`.
+"""
+function diagonal(v::AbstractVector)
+  ax = axes(v, 1) # Base.axes1 is private
+  return diagonal(v, (ax, ax))
+end
+function diagonal(v::AbstractVector, ax)
+  vax = axes(v, 1)
+  ax == (vax, vax) || throw(ArgumentError(lazy"Cannot create a `Diagonal` with axes $ax"))
+  return LinearAlgebra.Diagonal(v)
+end

test/Project.toml

@@ -1,6 +1,7 @@
 [deps]
 Aqua = "4c88cf16-eb10-579e-8560-4a9242c79595"
 DiagonalArrays = "74fd4be6-21e2-4f6f-823a-4360d37c7a77"
+LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 SafeTestsets = "1bc83da4-3b8d-516f-aca4-4fe02f6d838f"
 SparseArraysBase = "0d5efcca-f356-4864-8770-e1ed8d78f208"
 Suppressor = "fd094767-a336-5f1f-9728-57cf17d0bbfb"

test/test_basics.jl

@@ -1,6 +1,8 @@
-using Test: @test, @testset, @test_broken
-using DiagonalArrays: DiagonalArrays, DiagonalArray, DiagonalMatrix, diaglength
+using Test: @test, @testset, @test_broken, @inferred
+using DiagonalArrays: DiagonalArrays, DiagonalArray, DiagonalMatrix, diaglength, diagonal
 using SparseArraysBase: SparseArrayDOK, storedlength
+using LinearAlgebra: Diagonal
+
 @testset "Test DiagonalArrays" begin
   @testset "DiagonalArray (eltype=$elt)" for elt in (
     Float32, Float64, Complex{Float32}, Complex{Float64}
@@ -46,5 +48,9 @@ using SparseArraysBase: SparseArrayDOK, storedlength
       @test storedlength(a_dest) == 2
       @test a_dest isa SparseArrayDOK{elt,2}
     end
+    @testset "diagonal" begin
+      @test @inferred(diagonal(rand(2))) isa AbstractMatrix
+      @test diagonal(zeros(Int, 2)) isa Diagonal
+    end
   end
 end