Add OffsetMatrix type alias (#131)

Author: sostock

src/OffsetArrays.jl

@@ -7,7 +7,7 @@ else
     using Base: IdentityUnitRange
 end
 
-export OffsetArray, OffsetVector
+export OffsetArray, OffsetMatrix, OffsetVector
 
 include("axes.jl")
 
@@ -17,6 +17,7 @@ struct OffsetArray{T,N,AA<:AbstractArray} <: AbstractArray{T,N}
     offsets::NTuple{N,Int}
 end
 OffsetVector{T,AA<:AbstractArray} = OffsetArray{T,1,AA}
+OffsetMatrix{T,AA<:AbstractArray} = OffsetArray{T,2,AA}
 
 ## OffsetArray constructors
 
@@ -44,6 +45,10 @@ OffsetArray{T}(init::ArrayInitializer, inds::Vararg{AbstractUnitRange,N}) where
 OffsetVector(A::AbstractVector, offset) = OffsetArray(A, offset)
 OffsetVector{T}(init::ArrayInitializer, inds::AbstractUnitRange) where {T} = OffsetArray{T}(init, inds)
 
+# OffsetMatrix constructors
+OffsetMatrix(A::AbstractMatrix, offset1, offset2) = OffsetArray(A, offset1, offset2)
+OffsetMatrix{T}(init::ArrayInitializer, inds1::AbstractUnitRange, inds2::AbstractUnitRange) where {T} = OffsetArray{T}(init, inds1, inds2)
+
 """
     OffsetArray(A, indices...)
 

test/runtests.jl

@@ -108,6 +108,13 @@ end
     @test typeof(OffsetVector{Float64}(undef, -2:2)) == typeof(OffsetArray{Float64}(undef, -2:2))
 end
 
+@testset "OffsetMatrix constructors" begin
+    local v = rand(5, 3)
+    @test OffsetMatrix(v, -2, -1) == OffsetArray(v, -2, -1)
+    @test OffsetMatrix(v, -2:2, -1:1) == OffsetArray(v, -2:2, -1:1)
+    @test typeof(OffsetMatrix{Float64}(undef, -2:2, -1:1)) == typeof(OffsetArray{Float64}(undef, -2:2, -1:1))
+end
+
 @testset "undef, missing, and nothing constructors" begin
     y = OffsetArray{Float32}(undef, (IdentityUnitRange(-1:1),))
     @test axes(y) == (IdentityUnitRange(-1:1),)