Reducer behaviour not consistent over 1-dimensional arrays

[aahaselgrove]

I was looking at #16606 this morning and am not 100% on-board with the dropdims solution - as commented by others, I feel like it obfuscates the purpose of the code, which is performing the reduction.

I just noticed that, working with a 1-dimensional array, a reduction gives me a single value, automatically dropping the dimension. This seems inconsistent with behaviour for higher-dimensional arrays. Is this intended?

[StefanKarpinski]

Thanks for the report. However, the behavior is consistent and has nothing to do with the dimensionality of the input: reducers without the dims keyword argument return a scalar:

julia> A = rand(3, 4)
3×4 Array{Float64,2}:
 0.195413  0.543549  0.63676   0.872648
 0.931781  0.892374  0.233773  0.0597087
 0.48907   0.896954  0.317274  0.676223

julia> sum(A)
6.745528428752973

julia> sum(A, dims=(1,2))
1×1 Array{Float64,2}:
 6.745528428752973

[mbauman]

Yes, this is intended. For the vector case specifically, it's:

julia> sum(ones(3))
3.0

julia> sum(ones(3), dims=1)
1-element Array{Float64,1}:
 3.0