I have an Array{T,N+1} and I want to pass a slice/view of the first N dimensions to a function. If I knew, say, N=2 I would do b = @view a[:,:,1] f(b,args...) But the number of colons depends on N. Is there a way to do this for general N?

Or also selectdim(array,dim_to_select,indx_on_that_dim), e.g. b = selectdim(a,3,1)

[image] GitHub - SciML/EllipsisNotation.jl: Julia-based implementation of ellipsis... Julia-based implementation of ellipsis array indexing notation `..` - GitHub - SciML/EllipsisNotation.jl: Julia-based implementation of ellipsis array indexing notation `..`

I really like the solution with selectdim(), but I add this one too vv = @view v[ntuple(_->:,ndims(v)-1)...,1]

Does this produce a “view” or copy to a new array?

A tupple of colons! Didn’t know you could do that!

a view Arrays · The Julia Language

As far as I understand (:) is a function, like isless() for example It should be equivalent (alias?) of Colon(). But let’s wait for someone who knows to explain better how it works :slight_smile:

Just try it :slight_smile:: julia> x = [1 2; 3 4] 2×2 Matrix{Int64}: 1 2 3 4 julia> xd2_1 = selectdim(x,2,1) 2-element view(::Matrix{Int64}, :, 1) with eltype Int64: 1 3 julia> xd2_1[2] = 30 30 julia> x 2×2 Matrix{Int64}: 1 2 30 4

[image] rocco_sprmnt21: As far as I understand (:) is a function, like isless() for example It should be equivalent (alias?) of Colon(). That’s right: JuliaLang/julia/blob/94bc2f3c9f424071a2ef11c348f19a3cdf444603/base/essentials.jl#LL821C1-L823C20 struct Col…

I don’t have Julia installed on my phone… yet!

N-dimensional view into an N+1 dimension array

General Usage

jishnub May 24, 2023, 7:14pm 2

2 Likes

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N-dimensional view into an N+1 dimension array

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