Implicitly specify axes using colons in the constructor (#139)

In case certain axes of an array are not offset, they may be implicitly specified using Colons in the constructor. The colons would be replaced by the corresponding axes of the parent array.

Author: jishnub

src/OffsetArrays.jl

@@ -77,6 +77,17 @@ end
 OffsetArray(A::AbstractArray{T,N}, inds::Vararg{AbstractUnitRange,N}) where {T,N} =
     OffsetArray(A, inds)
 
+uncolonindices(A::AbstractArray{<:Any,N}, inds::NTuple{N,Any}) where {N} = uncolonindices(axes(A), inds)
+uncolonindices(ax::Tuple, inds::Tuple) = (first(inds), uncolonindices(tail(ax), tail(inds))...)
+uncolonindices(ax::Tuple, inds::Tuple{Colon, Vararg{Any}}) = (first(ax), uncolonindices(tail(ax), tail(inds))...)
+uncolonindices(::Tuple{}, ::Tuple{}) = ()
+
+function OffsetArray(A::AbstractArray{T,N}, inds::NTuple{N,Union{AbstractUnitRange, Colon}}) where {T,N}
+    OffsetArray(A, uncolonindices(A, inds))
+end
+OffsetArray(A::AbstractArray{T,N}, inds::Vararg{Union{AbstractUnitRange, Colon},N}) where {T,N} =
+    OffsetArray(A, uncolonindices(A, inds))
+
 # avoid a level of indirection when nesting OffsetArrays
 function OffsetArray(A::OffsetArray, offsets::NTuple{N,Int}) where {N}
     OffsetArray(parent(A), offsets .+ A.offsets)

test/runtests.jl

@@ -109,13 +109,31 @@ end
     @test OffsetVector(v, -2) == OffsetArray(v, -2)
     @test OffsetVector(v, -2:2) == OffsetArray(v, -2:2)
     @test typeof(OffsetVector{Float64}(undef, -2:2)) == typeof(OffsetArray{Float64}(undef, -2:2))
+
+    @test OffsetVector(v, :) == OffsetArray(v, (:,)) == OffsetArray(v, :) == OffsetArray(v, axes(v))
+    @test axes(OffsetVector(v, :)) == axes(v)
+
+    w = zeros(5:6)
+    @test OffsetVector(w, :) == OffsetArray(w, (:,)) == OffsetArray(w, :) == OffsetArray(w, axes(w))
+    @test axes(OffsetVector(w, :)) == axes(w)
 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))
+
+    @test OffsetMatrix(v, :, :) == OffsetArray(v, (:, :)) == OffsetArray(v, :, :) == OffsetArray(v, axes(v))
+    @test OffsetMatrix(v, :, 2:4) == OffsetArray(v, axes(v,1), 2:4)
+    @test OffsetMatrix(v, 3:7, :) == OffsetArray(v, 3:7, axes(v,2))
+    @test axes(OffsetArray(v, :, :)) == axes(v)
+
+    w = zeros(3:4, 5:6)
+    @test OffsetMatrix(w, :, :) == OffsetArray(w, (:, :)) == OffsetArray(w, :, :) == OffsetArray(w, axes(w))
+    @test OffsetMatrix(w, :, 2:3) == OffsetArray(w, axes(w,1), 2:3)
+    @test OffsetMatrix(w, 0:1, :) == OffsetArray(w, 0:1, axes(w,2))
+    @test axes(OffsetArray(w, :, :)) == axes(w)
 end
 
 @testset "undef, missing, and nothing constructors" begin