Speeding up sort along an array dimension

General Usage Performance
,
7

On my computer this code (which is the same as @lmiq suggests)

function mysort3!(a::AbstractArray{<:Any, 4})
    Threads.@threads for k in axes(a, 4)
        for j in axes(a, 2)
            for i in axes(a, 1)
                sort!(view(a, i, j, :, k))
            end
        end
    end
    return a
end

gives more than 8x speedup for 8 threads.

Unfortunately, I cannot find a way to select which dimension to sort, since there is apparently no generalization of eachrow and eachcol. eachslice and selectdim does not have the right behaviour. But hardcoding the dimension works.

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