Nice display for ReshapedOneD (#230)

While `ReshapedOneD` is not itself an AbstractArray (due to needing to
handle IIR types too), it often contains one. In such ases, there are
obvious mechanisms to improve the display.

With this PR, we get:
```julia
julia> kern1, kern2 = kernelfactors((centered([1, 2, 1]), [-1, 0, 1]));

julia> kern1
Reshaped 1d stencil with axes (-1:1, 0:0):
 1
 2
 1

julia> kern2
Reshaped 1d stencil with axes (0:0, 1:3):
 -1  0  1
```

Author: timholy

src/kernelfactors.jl

@@ -76,6 +76,20 @@ Base.isempty(A::ReshapedOneD) = isempty(A.data)
 
 @inline Base.axes(A::ReshapedOneD{_,N,Npre}) where {_,N,Npre} = Base.fill_to_length((Base.ntuple(d->0:0, Val(Npre))..., UnitRange(Base.axes1(A.data))), 0:0, Val(N))
 
+function Base.show(io::IO, ::MIME"text/plain", A::ReshapedOneD{T,N,Npre,<:AbstractVector}) where {T,N,Npre}
+    println(io, "Reshaped 1d stencil with axes ", axes(A), ":")
+    if ndims(A) <= 2
+        # print in matrix style
+        a = OffsetArray{T}(undef, axes(A)...)
+        for i in CartesianIndices(axes(A))
+            a[i] = A[i]
+        end
+        Base.print_array(io, a)
+    else
+        println(io, "  with data: ", A.data)
+    end
+end
+
 Base.iterate(A::ReshapedOneD) = iterate(A.data)
 Base.iterate(A::ReshapedOneD, state) = iterate(A.data, state)
 

test/basic.jl

@@ -33,6 +33,26 @@ using AxisArrays: AxisArray, Axis
     @test KernelFactors.kernelfactors(([0,3], [1,7]))  == (reshape([0,3], 1:2, 0:0), reshape([1,7], 0:0, 1:2))
     @test KernelFactors.kernelfactors(([0,3], [1,7]')) == (reshape([0,3], 2, 1), reshape([1,7], 1, 2))
 
+    io = IOBuffer()
+    kern1, kern2 = kernelfactors((centered([1, 2, 1]), [-1, 0, 1]))
+    show(io, MIME("text/plain"), kern1)
+    str = String(take!(io))
+    @test occursin("Reshaped 1d stencil with axes (-1:1, 0:0)", str)
+    @test occursin(r"1\n\s?2\n\s?1"s, str)
+    show(io, MIME("text/plain"), kern2)
+    str = String(take!(io))
+    @test occursin("Reshaped 1d stencil with axes (0:0, 1:3)", str)
+    @test occursin(r"-1\s+0\s+1"s, str)
+    kern1, kern2, kern3 = kernelfactors((centered([1, 2, 1]), [-1, 0, 1], [1, 1, 1]))
+    show(io, MIME("text/plain"), kern1)
+    str = String(take!(io))
+    @test occursin("Reshaped 1d stencil with axes (-1:1, 0:0, 0:0)", str)
+    @test occursin("with data: [1, 2, 1]", str)
+    show(io, MIME("text/plain"), kern3)
+    str = String(take!(io))
+    @test occursin("Reshaped 1d stencil with axes (0:0, 0:0, 1:3)", str)
+    @test occursin("with data: [1, 1, 1]", str)
+
     tiles = ImageFiltering.tile_allocate(Float32, (rand(3),rand(3)'))
     @test isa(tiles, Vector{Matrix{Float32}})
     @test length(tiles) == Threads.nthreads()