add length interface

Author: huanglangwen

src/ArrayInterface.jl

@@ -58,6 +58,7 @@ end
 
 Base.firstindex(ind::MatrixIndex)=1
 Base.lastindex(ind::MatrixIndex)=ind.count
+Base.length(ind::MatrixIndex)=ind.count
 function Base.getindex(ind::BidiagonalIndex,i::Int)
   1 <= i <= ind.count || throw(BoundsError(ind, i))
   if ind.isup

test/runtests.jl

@@ -10,27 +10,29 @@ using LinearAlgebra, SparseArrays
 D=Diagonal([1,2,3,4])
 @test has_sparsestruct(D)
 rowind,colind=findstructralnz(D)
-@test [D[rowind[i],colind[i]] for i in 1:4]==[1,2,3,4]
+@test [D[rowind[i],colind[i]] for i in 1:length(rowind)]==[1,2,3,4]
+@test length(rowind)==4
+@test length(rowind)==length(colind)
 
 Bu = Bidiagonal([1,2,3,4], [7,8,9], :U)
 @test has_sparsestruct(Bu)
 rowind,colind=findstructralnz(Bu)
-@test [Bu[rowind[i],colind[i]] for i in 1:7]==[1,7,2,8,3,9,4]
+@test [Bu[rowind[i],colind[i]] for i in 1:length(rowind)]==[1,7,2,8,3,9,4]
 Bl = Bidiagonal([1,2,3,4], [7,8,9], :L)
 @test has_sparsestruct(Bl)
 rowind,colind=findstructralnz(Bl)
-@test [Bl[rowind[i],colind[i]] for i in 1:7]==[1,7,2,8,3,9,4]
+@test [Bl[rowind[i],colind[i]] for i in 1:length(rowind)]==[1,7,2,8,3,9,4]
 
 Tri=Tridiagonal([1,2,3],[1,2,3,4],[4,5,6])
 @test has_sparsestruct(Tri)
 rowind,colind=findstructralnz(Tri)
-@test [Tri[rowind[i],colind[i]] for i in 1:10]==[1,2,3,4,4,5,6,1,2,3]
+@test [Tri[rowind[i],colind[i]] for i in 1:length(rowind)]==[1,2,3,4,4,5,6,1,2,3]
 STri=SymTridiagonal([1,2,3,4],[5,6,7])
 @test has_sparsestruct(STri)
 rowind,colind=findstructralnz(STri)
-@test [STri[rowind[i],colind[i]] for i in 1:10]==[1,2,3,4,5,6,7,5,6,7]
+@test [STri[rowind[i],colind[i]] for i in 1:length(rowind)]==[1,2,3,4,5,6,7,5,6,7]
 
 Sp=sparse([1,2,3],[1,2,3],[1,2,3])
 @test has_sparsestruct(Sp)
 rowind,colind=findstructralnz(Sp)
-@test [Tri[rowind[i],colind[i]] for i in 1:3]==[1,2,3]
+@test [Tri[rowind[i],colind[i]] for i in 1:length(rowind)]==[1,2,3]