All possible combinations of indices in an array, as in nested multiple loops
combinations, julia
Solution
It's not clear to me what you mean by "I want to obtain" and `\\ get [i, j, k]`, but you may find this useful/interesting.
julia> using Iterators
julia> collect(product(repeated(1:2,3)...))
8-element Array{(Int32,Int32,Int32),1}:
(1,1,1)
(2,1,1)
(1,2,1)
(2,2,1)
(1,1,2)
(2,1,2)
(1,2,2)
(2,2,2)
julia> A=reshape(1:8,(2,2,2))
2x2x2 Array{Int32,3}:
[:, :, 1] =
1 3
2 4
[:, :, 2] =
5 7
6 8
julia> for i in product(repeated(1:2,3)...)
@show A[i...]
end
A[i...] => 1
A[i...] => 2
A[i...] => 3
A[i...] => 4
A[i...] => 5
A[i...] => 6
A[i...] => 7
A[i...] => 8
julia> cartesianmap((k...)->println(A[k...]^2+1),tuple(repeated(2,3)...))
2
5
10
17
26
37
50
65
or even without the `Iterators` package ...
julia> cartesianmap((k...)->println(A[k...]),tuple(repmat([2],3)...))
1
2
3
4
5
6
7
8
Problem
There is an array `[1, 2, ..., m]`, and there is an integer `n`. If `m=2` and `n=3`, I want to obtain ``` [1, 1, 1] [1, 1, 2] [1, 2, 1] [1, 2, 2] [2, 1, 1] [2, 1, 2] [2, 2, 1] [2, 2, 2] ``` It's like I do ``` for i=1:m for j=1:m for k=1:m \\ get [i, j, k] end end end ``` But, both `m` and `n` are variables. How can I do this? I'm using Julia, but any general advice would be fine.