Faster band indexing for BandedMatrix (#331)

* Faster band indexing for BandedMatrix

* only fill elements inrange

* recursive in setdocsmeta

* docstest setup

* remove duplicate doctests

* remove jldoctest setup

Author: jishnub

.github/workflows/docs.yml

@@ -17,13 +17,8 @@ jobs:
       - run: |
           julia --project=docs -e '
             using Pkg
-            Pkg.develop(PackageSpec(path=pwd()))
+            Pkg.develop(PackageSpec(; path=pwd()))
             Pkg.instantiate()'
-      - run: |
-          julia --project=docs -e '
-            using Documenter: doctest
-            using BandedMatrices
-            doctest(BandedMatrices)'
       - run: julia --project=docs docs/make.jl
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

Project.toml

@@ -1,6 +1,6 @@
 name = "BandedMatrices"
 uuid = "aae01518-5342-5314-be14-df237901396f"
-version = "0.17.14"
+version = "0.17.15"
 
 [deps]
 ArrayLayouts = "4c555306-a7a7-4459-81d9-ec55ddd5c99a"

docs/make.jl

@@ -1,19 +1,16 @@
 using Documenter, BandedMatrices
 
+DocMeta.setdocmeta!(BandedMatrices, :DocTestSetup, :(using BandedMatrices); recursive=true)
 makedocs(;
     modules = [BandedMatrices],
-    format = Documenter.HTML(
-        canonical = "https://JuliaMatrices.github.io/BandedMatrices.jl/stable/",
-    ),
     pages = [
         "Home" => "index.md",
     ],
-    repo = "https://github.com/JuliaMatrices/BandedMatrices.jl/blob/{commit}{path}#L{line}",
     sitename = "BandedMatrices.jl",
     authors = "Sheehan Olver, Mikael Slevinsky, and contributors.",
 )
 
 
 deploydocs(;
-    repo   = "github.com/JuliaMatrices/BandedMatrices.jl.git"
+    repo   = "github.com/JuliaLinearAlgebra/BandedMatrices.jl.git"
     )

src/BandedMatrices.jl

@@ -7,7 +7,7 @@ import Base: axes, axes1, getproperty, getindex, setindex!, *, +, -, ==, <, <=,
                >=, /, ^, \, adjoint, transpose, showerror, convert, size, view,
                unsafe_indices, first, last, size, length, unsafe_length, step, to_indices,
                to_index, show, fill!, similar, copy, promote_rule, IndexStyle, real, imag,
-               copyto!
+               copyto!, Array
 
 using Base.Broadcast: AbstractArrayStyle, DefaultArrayStyle, Broadcasted
 import Base.Broadcast: BroadcastStyle, broadcasted, materialize, materialize!

src/banded/BandedMatrix.jl

@@ -395,51 +395,70 @@ end
 # we reduce it to converting a View
 
 
-# type to represent a view of a band
-const BandedMatrixBand{T} = SubArray{T, 1, ReshapedArray{T,1,BandedMatrix{T},
-                                Tuple{MultiplicativeInverses.SignedMultiplicativeInverse{Int}}}, Tuple{BandSlice}, false}
+"""
+    BandedMatrixBand
+
+Type to represent a view of a band of a `BandedMatrix`
+
+# Examples
+```jldoctest
+julia> B = BandedMatrix(0=>1:3);
+
+julia> view(B, band(0)) isa BandedMatrices.BandedMatrixBand
+true
+```
+"""
+const BandedMatrixBand{T} = SubArray{T, 1, <:ReshapedArray{T,1,<:BandedMatrix{T}}, Tuple{BandSlice}}
 
 
 band(V::BandedMatrixBand) = first(parentindices(V)).band.i
 
-# gives a view of the parent's data matrix
+
+"""
+    dataview(V::BandedMatrices.BandedMatrixBand)
+
+Forward a view of a band of a `BandedMatrix` to the parent's data matrix.
+
+# Examples
+```jldoctest
+julia> A = BandedMatrix(0=>1:4, 1=>5:7, -1=>8:10)
+4×4 BandedMatrix{Int64} with bandwidths (1, 1):
+ 1  5   ⋅  ⋅
+ 8  2   6  ⋅
+ ⋅  9   3  7
+ ⋅  ⋅  10  4
+
+julia> v = view(A, band(1))
+3-element view(reshape(::BandedMatrix{Int64, Matrix{Int64}, Base.OneTo{Int64}}, 16), BandSlice(Band(1), 5:5:15)) with eltype Int64:
+ 5
+ 6
+ 7
+
+julia> BandedMatrices.dataview(v)
+3-element view(::Matrix{Int64}, 1, 2:4) with eltype Int64:
+ 5
+ 6
+ 7
+```
+"""
 function dataview(V::BandedMatrixBand)
     A = parent(parent(V))
     b = band(V)
     m,n = size(A)
-    if b > 0
-        view(A.data, A.u - b + 1, b+1:min(n,m+b))
-    elseif b == 0
-        view(A.data, A.u - b + 1, 1:min(n,m))
-    else # b < 0
-        view(A.data, A.u - b + 1, 1:min(n,m+b))
-    end
+    view(A.data, A.u - b + 1, max(b,0)+1:min(n,m+b))
 end
 
-function convert(::Type{Vector{T}}, V::BandedMatrixBand) where T
-    A = parent(parent(V))
-    if -A.l ≤ band(V) ≤ A.u
-        Vector{T}(dataview(V))
+function copyto!(v::Vector, B::BandedMatrixBand)
+    A = parent(parent(B))
+    if -A.l ≤ band(B) ≤ A.u
+        copyto!(v, dataview(B))
     else
-        zeros(T, length(V))
+        Binds = axes(B,1)
+        v[Binds] .= 0
     end
+    return v
 end
 
-convert(::Type{Array{T}}, A::BandedMatrixBand) where T = convert(Vector{T}, A)
-convert(::Type{Array}, A::BandedMatrixBand) = convert(Vector{eltype(A)}, A)
-convert(::Type{Vector}, A::BandedMatrixBand)= convert(Vector{eltype(A)}, A)
-
-
-convert(::Type{AbstractArray{T}}, A::BandedMatrixBand{T}) where T = A
-convert(::Type{AbstractVector{T}}, A::BandedMatrixBand{T}) where T = A
-convert(::Type{AbstractArray}, A::BandedMatrixBand{T}) where T = A
-convert(::Type{AbstractVector}, A::BandedMatrixBand{T}) where T = A
-
-convert(::Type{AbstractArray{T}}, A::BandedMatrixBand) where T = convert(Vector{T}, A)
-convert(::Type{AbstractVector{T}}, A::BandedMatrixBand) where T = convert(Vector{T}, A)
-
-
-
 # ~ indexing along a row
 
 

src/generic/Band.jl

@@ -194,7 +194,7 @@ the indices over which the `Band` spans.
 This mimics the relationship between `Colon` and `Base.Slice`.
 
 # Example
-```jldoctest; setup=:(using BandedMatrices)
+```jldoctest
 julia> B = BandedMatrix(0 => 1:4, 1=>1:3);
 
 julia> to_indices(B, (Band(1),))[1]

test/runtests.jl

@@ -9,6 +9,7 @@ using Aqua
 end
 
 using Documenter
+DocMeta.setdocmeta!(BandedMatrices, :DocTestSetup, :(using BandedMatrices))
 @testset "doctests" begin
     doctest(BandedMatrices)
 end