Add delta constructors and other missing constructors (#22)

Author: mtfishman

Project.toml

@@ -1,7 +1,7 @@
 name = "ITensorBase"
 uuid = "4795dd04-0d67-49bb-8f44-b89c448a1dc7"
 authors = ["ITensor developers <[email protected]> and contributors"]
-version = "0.1.10"
+version = "0.1.11"
 
 [deps]
 Accessors = "7d9f7c33-5ae7-4f3b-8dc6-eff91059b697"
@@ -14,9 +14,16 @@ UnallocatedArrays = "43c9e47c-e622-40fb-bf18-a09fc8c466b6"
 UnspecifiedTypes = "42b3faec-625b-4613-8ddc-352bf9672b8d"
 VectorInterface = "409d34a3-91d5-4945-b6ec-7529ddf182d8"
 
+[weakdeps]
+DiagonalArrays = "74fd4be6-21e2-4f6f-823a-4360d37c7a77"
+
+[extensions]
+ITensorBaseDiagonalArraysExt = "DiagonalArrays"
+
 [compat]
 Accessors = "0.1.39"
 DerivableInterfaces = "0.3.7"
+DiagonalArrays = "0.2.3"
 FillArrays = "1.13.0"
 LinearAlgebra = "1.10"
 MapBroadcast = "0.1.5"

ext/ITensorBaseDiagonalArraysExt/ITensorBaseDiagonalArraysExt.jl

@@ -0,0 +1,28 @@
+module ITensorBaseDiagonalArraysExt
+
+using DiagonalArrays: DiagonalArrays, δ, delta
+using ITensorBase: ITensor, Index
+
+# TODO: Define more generic definitions in `NamedDimsArraysDiagonalArraysExt`.
+function DiagonalArrays.delta(elt::Type{<:Number}, is::Tuple{Index,Vararg{Index}})
+  return ITensor(delta(elt, Int.(length.(is))), is)
+end
+function DiagonalArrays.δ(elt::Type{<:Number}, is::Tuple{Index,Vararg{Index}})
+  return delta(elt, is)
+end
+DiagonalArrays.delta(is::Tuple{Index,Vararg{Index}}) = delta(Bool, is)
+DiagonalArrays.δ(is::Tuple{Index,Vararg{Index}}) = delta(is)
+function DiagonalArrays.delta(elt::Type{<:Number}, i1::Index, i_rest::Index...)
+  return delta(elt, (i1, i_rest...))
+end
+function DiagonalArrays.δ(elt::Type{<:Number}, i1::Index, i_rest::Index...)
+  return delta(elt, i1, i_rest...)
+end
+function DiagonalArrays.delta(i1::Index, i_rest::Index...)
+  return delta((i1, i_rest...))
+end
+function DiagonalArrays.δ(i1::Index, i_rest::Index...)
+  return delta(i1, i_rest...)
+end
+
+end

src/abstractitensor.jl

@@ -84,6 +84,13 @@ end
 Base.parent(a::ITensor) = a.parent
 NamedDimsArrays.nameddimsindices(a::ITensor) = a.nameddimsindices
 
+function ITensor(parent::AbstractArray, i1::Index, i_rest::Index...)
+  return ITensor(parent, (i1, i_rest...))
+end
+function ITensor(parent::AbstractArray)
+  return ITensor(parent, ())
+end
+
 using Accessors: @set
 setdenamed(a::ITensor, denamed) = (@set a.parent = denamed)
 setdenamed!(a::ITensor, denamed) = (a.parent = denamed)

src/quirks.jl

@@ -12,16 +12,6 @@ dim(a::AbstractITensor) = Int(length(a))
 hasqns(i::Index) = false
 # TODO: Define this properly.
 hasqns(i::AbstractITensor) = false
-# TODO: Deprecate, and/or decide on aliasing behavior of `ITensor`.
-itensor(parent::AbstractArray, nameddimsindices) = ITensor(parent, nameddimsindices)
-function itensor(parent::AbstractArray, i1::Index, i_rest::Index...)
-  return ITensor(parent, (i1, i_rest...))
-end
-# TODO: Deprecate.
-order(a::AbstractArray) = ndims(a)
-# TODO: Deprecate.
-using NamedDimsArrays: aligndims
-permute(a::AbstractITensor, dimnames) = aligndims(a, dimnames)
 
 # This seems to be needed to get broadcasting working.
 # TODO: Investigate this and see if we can get rid of it.
@@ -30,11 +20,12 @@ Base.Broadcast.extrude(a::AbstractITensor) = a
 # TODO: Generalize this.
 # Maybe define it as `oneelement`, and base it on
 # `FillArrays.OneElement` (https://juliaarrays.github.io/FillArrays.jl/stable/#FillArrays.OneElement).
-function onehot(iv::Pair{<:Index,<:Int})
+function onehot(elt::Type{<:Number}, iv::Pair{<:Index,<:Int})
   a = ITensor(first(iv))
-  a[last(iv)] = one(Bool)
+  a[last(iv)] = one(elt)
   return a
 end
+onehot(iv::Pair{<:Index,<:Int}) = onehot(Bool, iv)
 
 # TODO: This is just a stand-in for truncated SVD
 # that only makes use of `maxdim`, just to get some
@@ -79,12 +70,3 @@ function factorize(
   end
   return F1, F2, (; truncerr=zero(Bool),)
 end
-
-# TODO: Used in `ITensorMPS.jl`, decide where or if to define it.
-# Ideally this would just be a zero-dimensional `ITensor` wrapping
-# a special type, like `Zeros{UnspecifiedZero()}()`.
-struct OneITensor <: AbstractITensor end
-Base.size(::OneITensor) = ()
-Base.:*(::OneITensor, ::OneITensor) = OneITensor()
-Base.:*(::OneITensor, a::ITensor) = a
-Base.:*(a::ITensor, ::OneITensor) = a

test/Project.toml

@@ -1,5 +1,6 @@
 [deps]
 Aqua = "4c88cf16-eb10-579e-8560-4a9242c79595"
+DiagonalArrays = "74fd4be6-21e2-4f6f-823a-4360d37c7a77"
 ITensorBase = "4795dd04-0d67-49bb-8f44-b89c448a1dc7"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 NamedDimsArrays = "60cbd0c0-df58-4cb7-918c-6f5607b73fde"

test/test_basics.jl

@@ -1,21 +1,43 @@
 using ITensorBase: ITensorBase, ITensor, Index, gettag, inds, plev, prime, settag, unsettag
+using DiagonalArrays: δ, delta, diagview
 using NamedDimsArrays: unname
-using Test: @test, @testset
+using Test: @test, @test_broken, @testset
 
 @testset "ITensorBase" begin
-  i, j = Index.((2, 2))
-  x = randn(2, 2)
-  a = ITensor(x, (i, j))
-  @test unname(a) == x
-  @test plev(i) == 0
-  @test plev(prime(i)) == 1
-  a′ = prime(a)
-  @test unname(a′) == x
-  @test issetequal(inds(a′), (prime(i), prime(j)))
+  @testset "Basics" begin
+    i, j = Index.((2, 2))
+    x = randn(2, 2)
+    for a in (ITensor(x, i, j), ITensor(x, (i, j)))
+      @test unname(a) == x
+      @test plev(i) == 0
+      @test plev(prime(i)) == 1
+      a′ = prime(a)
+      @test unname(a′) == x
+      @test issetequal(inds(a′), (prime(i), prime(j)))
+    end
 
-  i = Index(2)
-  i = settag(i, "X", "x")
-  @test gettag(i, "X") == "x"
-  i = unsettag(i, "X")
-  @test isnothing(gettag(i, "X", nothing))
+    i = Index(2)
+    i = settag(i, "X", "x")
+    @test gettag(i, "X") == "x"
+    i = unsettag(i, "X")
+    @test isnothing(gettag(i, "X", nothing))
+  end
+  @testset "delta" begin
+    i, j = Index.((2, 2))
+    for a in (
+      delta(i, j),
+      delta(Bool, i, j),
+      delta((i, j)),
+      delta(Bool, (i, j)),
+      δ(i, j),
+      δ(Bool, i, j),
+      δ((i, j)),
+      δ(Bool, (i, j)),
+    )
+      @test eltype(a) === Bool
+      # TODO: Fix this.
+      @test_broken diagview(a)
+      @test diagview(unname(a)) == ones(2)
+    end
+  end
 end