recognize Adjoint/Transpose of sparse arrays as sparse (#34266)

Author: dkarrasch

stdlib/SparseArrays/src/abstractsparse.jl

@@ -52,6 +52,8 @@ false
 """
 issparse(A::AbstractArray) = false
 issparse(S::AbstractSparseArray) = true
+issparse(S::LinearAlgebra.Adjoint{<:Any,<:AbstractSparseArray}) = true
+issparse(S::LinearAlgebra.Transpose{<:Any,<:AbstractSparseArray}) = true
 
 issparse(S::LinearAlgebra.Symmetric{<:Any,<:AbstractSparseMatrix}) = true
 issparse(S::LinearAlgebra.Hermitian{<:Any,<:AbstractSparseMatrix}) = true

stdlib/SparseArrays/test/sparse.jl

@@ -2046,6 +2046,8 @@ end
     @test issparse(LinearAlgebra.UnitLowerTriangular(m))
     @test issparse(UpperTriangular(m))
     @test issparse(LinearAlgebra.UnitUpperTriangular(m))
+    @test issparse(adjoint(m))
+    @test issparse(transpose(m))
     @test issparse(Symmetric(Array(m))) == false
     @test issparse(Hermitian(Array(m))) == false
     @test issparse(LowerTriangular(Array(m))) == false
@@ -2054,6 +2056,13 @@ end
     @test issparse(LinearAlgebra.UnitUpperTriangular(Array(m))) == false
 end
 
+@testset "issparse for sparse vectors #34253" begin
+    v = sprand(10, 0.5)
+    @test issparse(v)
+    @test issparse(v')
+    @test issparse(transpose(v))
+end
+
 @testset "test created type of sprand{T}(::Type{T}, m::Integer, n::Integer, density::AbstractFloat)" begin
     m = sprand(Float32, 10, 10, 0.1)
     @test eltype(m) == Float32