blockcol/rowsupport for banded matrices (#117)

* blockcol/rowsupport for banded matrices

* add sub_materialize

Author: dlfivefifty

Project.toml

@@ -1,6 +1,6 @@
 name = "BlockBandedMatrices"
 uuid = "ffab5731-97b5-5995-9138-79e8c1846df0"
-version = "0.10.8"
+version = "0.10.9"
 
 [deps]
 ArrayLayouts = "4c555306-a7a7-4459-81d9-ec55ddd5c99a"

src/interfaceimpl.jl

@@ -133,4 +133,24 @@ subblockbandwidths(::Zeros) = (-1,-1)
 
 sublayout(::DiagonalLayout{L}, inds::Type{<:NTuple{2,BS}}) where {L,BS<:BlockSlice{<:BlockRange1}} = bandedblockbandedcolumns(sublayout(L(),Tuple{BS}))
 subblockbandwidths(::Diagonal) = (0,0)
-bandedblockbandeddata(D::Diagonal) = permutedims(D.diag)
+bandedblockbandeddata(D::Diagonal) = permutedims(D.diag)
+
+###
+# Block-BandedMatrix
+###
+
+function blockcolsupport(::AbstractBandedLayout, B, j)
+    m,n = axes(B)
+    cs = colsupport(B,n[Block.(j)])
+    findblock(m,first(cs)):findblock(m,last(cs))
+end
+
+function blockrowsupport(::AbstractBandedLayout, B, k)
+    m,n = axes(B)
+    rs = rowsupport(B,m[Block.(k)])
+    findblock(n,first(rs)):findblock(n,last(rs))
+end
+
+# ambiguity
+sub_materialize(::AbstractBandedLayout, V, ::Tuple{BlockedUnitRange,Base.OneTo{Int}}) = BandedMatrix(V)
+sub_materialize(::AbstractBandedLayout, V, ::Tuple{Base.OneTo{Int},BlockedUnitRange}) = BandedMatrix(V)

test/test_misc.jl

@@ -1,6 +1,6 @@
 using ArrayLayouts, BlockBandedMatrices, BandedMatrices, BlockArrays, LinearAlgebra, Test
-import BlockBandedMatrices: AbstractBandedBlockBandedMatrix, block, blockindex
-import BandedMatrices: bandwidths, AbstractBandedMatrix, BandedStyle, bandeddata, BandedColumns
+import BlockBandedMatrices: AbstractBandedBlockBandedMatrix, block, blockindex, blockcolsupport, blockrowsupport
+import BandedMatrices: bandwidths, AbstractBandedMatrix, BandedStyle, bandeddata, BandedColumns, _BandedMatrix
 
 struct MyBandedBlockBandedMatrix <: AbstractBandedBlockBandedMatrix{Float64}
     A::BlockMatrix{Float64}
@@ -124,4 +124,21 @@ end
         @test blockbandwidths(D[Block.(1:2),Block.(2:3)]) == (1,-1)
         @test subblockbandwidths(D[Block.(1:2),Block.(2:3)]) == (0,0)
     end
+
+    @testset "Block-BandedMatrix" begin
+        a = blockedrange(1:5)
+        B = _BandedMatrix(PseudoBlockArray(randn(5,length(a)),(Base.OneTo(5),a)), a, 3, 1)
+        @test blockcolsupport(B,1) == Block.(1:3)
+        @test blockcolsupport(B,3) == Block.(2:4)
+        @test blockrowsupport(B,1) == Block.(1:2)
+        @test blockrowsupport(B,4) == Block.(3:5)
+
+        Q = Eye((a,))[:,Block(2)]
+        @test Q isa BandedMatrix
+        @test blockcolsupport(Q,1) == Block.(2:2)
+
+        Q = Eye((a,))[Block(2),:]
+        @test Q isa BandedMatrix
+        @test blockrowsupport(Q,1) == Block.(2:2)
+    end
 end