Construct DiagonalTensorMap from SectorVector (#363)

Author: Yue-Zhengyuan

src/tensors/diagonal.jl

@@ -85,6 +85,17 @@ similar_diagonal(d::DiagonalTensorMap) = DiagonalTensorMap(similar(d.data), d.do
 similar_diagonal(d::DiagonalTensorMap, ::Type{T}) where {T <: Number} =
     DiagonalTensorMap(similar(d.data, T), d.domain)
 
+"""
+    DiagonalTensorMap(s::SectorVector)
+
+Construct a `DiagonalTensorMap` directly from a `SectorVector`,
+from which the codomain (assumed non-dual) is inferred automatically.
+"""
+function DiagonalTensorMap(s::SectorVector)
+    V = Vect[sectortype(s)](c => length(b) for (c, b) in blocks(s))
+    return DiagonalTensorMap(s.data, V)
+end
+
 # TODO: more constructors needed?
 
 # Special case adjoint:

test/cuda/factorizations.jl

@@ -217,6 +217,9 @@ for V in spacelist
                 @test parent(s′) ≈ parent(diagview(s))
                 @test s′ isa TensorKit.SectorVector
 
+                s2 = @constinferred DiagonalTensorMap(s′)
+                @test s2 ≈ s
+
                 v, c = @constinferred left_orth(t; alg = :svd)
                 @test v * c ≈ t
                 @test isisometric(v)
@@ -345,6 +348,9 @@ for V in spacelist
                 @test parent(d′) ≈ parent(diagview(d))
                 @test d′ isa TensorKit.SectorVector
 
+                d2 = @constinferred DiagonalTensorMap(d′)
+                @test d2 ≈ d
+
                 vdv = project_hermitian!(v' * v)
                 @test @constinferred isposdef(vdv)
                 t isa DiagonalTensorMap || @test !isposdef(t) # unlikely for non-hermitian map

test/tensors/factorizations.jl

@@ -196,6 +196,9 @@ for V in spacelist
                 @test s′ ≈ diagview(s)
                 @test s′ isa TensorKit.SectorVector
 
+                s2 = @constinferred DiagonalTensorMap(s′)
+                @test s2 ≈ s
+
                 v, c = @constinferred left_orth(t; alg = :svd)
                 @test v * c ≈ t
                 @test isisometric(v)
@@ -316,6 +319,9 @@ for V in spacelist
                 @test d′ ≈ diagview(d)
                 @test d′ isa TensorKit.SectorVector
 
+                d2 = @constinferred DiagonalTensorMap(d′)
+                @test d2 ≈ d
+
                 vdv = project_hermitian!(v' * v)
                 @test @constinferred isposdef(vdv)
                 t isa DiagonalTensorMap || @test !isposdef(t) # unlikely for non-hermitian map