Hi, I am new to Julia and I am attempting to figure out 3 dimensional arrays. The task at hand is to create a new 3-dimensional array that contains a 10x7x2 matrix in the first column of the third dimension and another 10x7x2 matrix in the second column of the third dimension.
Perhaps I do not understand the structure of a 3-dimensional array. Any help would be much appreciated, thank you.
This “matrix” already sounds 3-dimensional.
Column? or the 3rd dimension? Do I understand that you want to put two 3 dimensional “matrix” into another 3 dimensional array?
One way to interpret your statement is perhaps you are just trying to concatenate the two 3-dimensional “matrices” into a single 3-dimensional matrix.
You could do
julia> A
10×7×2 Array{Int64, 3}:
[:, :, 1] =
8 9 2 10 4 6 8
9 1 7 3 8 10 4
5 5 7 1 9 3 6
1 9 7 9 1 8 5
8 9 7 4 8 5 7
9 3 6 2 8 7 7
1 7 4 6 7 1 2
2 4 2 3 7 5 7
3 5 8 8 2 6 1
4 6 9 9 2 3 5
[:, :, 2] =
10 9 4 10 7 10 7
7 10 2 5 8 5 2
2 8 8 2 6 5 4
4 5 3 4 10 8 6
9 4 2 2 9 8 7
2 10 1 8 9 5 8
6 7 7 3 5 2 4
3 1 7 3 4 7 5
3 2 4 10 10 2 2
7 2 7 7 3 9 4
julia> B
10×7×2 Array{Int64, 3}:
[:, :, 1] =
6 8 5 8 9 1 3
7 3 2 2 6 5 8
3 2 8 3 10 6 9
1 3 2 3 1 2 9
5 3 1 10 2 7 10
1 10 1 10 3 5 4
9 8 9 8 2 7 3
6 5 9 7 2 4 5
5 7 3 4 9 1 8
9 7 2 8 7 7 8
[:, :, 2] =
7 9 8 4 8 3 8
4 10 3 4 9 4 1
1 6 10 6 5 3 6
1 6 9 1 9 10 2
1 5 1 1 8 8 6
2 7 7 9 4 9 2
4 10 7 4 10 1 7
2 7 3 2 2 3 6
1 10 2 7 10 3 2
1 8 1 9 6 6 3
julia> C = [A;;;B]
10×7×4 Array{Int64, 3}:
[:, :, 1] =
8 9 2 10 4 6 8
9 1 7 3 8 10 4
5 5 7 1 9 3 6
1 9 7 9 1 8 5
8 9 7 4 8 5 7
9 3 6 2 8 7 7
1 7 4 6 7 1 2
2 4 2 3 7 5 7
3 5 8 8 2 6 1
4 6 9 9 2 3 5
[:, :, 2] =
10 9 4 10 7 10 7
7 10 2 5 8 5 2
2 8 8 2 6 5 4
4 5 3 4 10 8 6
9 4 2 2 9 8 7
2 10 1 8 9 5 8
6 7 7 3 5 2 4
3 1 7 3 4 7 5
3 2 4 10 10 2 2
7 2 7 7 3 9 4
[:, :, 3] =
6 8 5 8 9 1 3
7 3 2 2 6 5 8
3 2 8 3 10 6 9
1 3 2 3 1 2 9
5 3 1 10 2 7 10
1 10 1 10 3 5 4
9 8 9 8 2 7 3
6 5 9 7 2 4 5
5 7 3 4 9 1 8
9 7 2 8 7 7 8
[:, :, 4] =
7 9 8 4 8 3 8
4 10 3 4 9 4 1
1 6 10 6 5 3 6
1 6 9 1 9 10 2
1 5 1 1 8 8 6
2 7 7 9 4 9 2
4 10 7 4 10 1 7
2 7 3 2 2 3 6
1 10 2 7 10 3 2
1 8 1 9 6 6 3
Perhaps you are really trying to do create an array of arrays. You could do
julia> D = reshape([A,B],1,1,2)
1×1×2 Array{Array{Int64, 3}, 3}:
[:, :, 1] =
[8 9 … 6 8; 9 1 … 10 4; … ; 3 5 … 6 1; 4 6 … 3 5;;; 10 9 … 10 7; 7 10 … 5 2; … ; 3 2 … 2 2; 7 2 … 9 4]
[:, :, 2] =
[6 8 … 1 3; 7 3 … 5 8; … ; 5 7 … 1 8; 9 7 … 7 8;;; 7 9 … 3 8; 4 10 … 4 1; … ; 1 10 … 3 2; 1 8 … 6 3]
julia> D[1]
10×7×2 Array{Int64, 3}:
[:, :, 1] =
8 9 2 10 4 6 8
9 1 7 3 8 10 4
5 5 7 1 9 3 6
1 9 7 9 1 8 5
8 9 7 4 8 5 7
9 3 6 2 8 7 7
1 7 4 6 7 1 2
2 4 2 3 7 5 7
3 5 8 8 2 6 1
4 6 9 9 2 3 5
[:, :, 2] =
10 9 4 10 7 10 7
7 10 2 5 8 5 2
2 8 8 2 6 5 4
4 5 3 4 10 8 6
9 4 2 2 9 8 7
2 10 1 8 9 5 8
6 7 7 3 5 2 4
3 1 7 3 4 7 5
3 2 4 10 10 2 2
7 2 7 7 3 9 4
julia> D[2]
10×7×2 Array{Int64, 3}:
[:, :, 1] =
6 8 5 8 9 1 3
7 3 2 2 6 5 8
3 2 8 3 10 6 9
1 3 2 3 1 2 9
5 3 1 10 2 7 10
1 10 1 10 3 5 4
9 8 9 8 2 7 3
6 5 9 7 2 4 5
5 7 3 4 9 1 8
9 7 2 8 7 7 8
[:, :, 2] =
7 9 8 4 8 3 8
4 10 3 4 9 4 1
1 6 10 6 5 3 6
1 6 9 1 9 10 2
1 5 1 1 8 8 6
2 7 7 9 4 9 2
4 10 7 4 10 1 7
2 7 3 2 2 3 6
1 10 2 7 10 3 2
1 8 1 9 6 6 3
That is my mistake, the two previous matrices are just 10x7. Here is the exact text:
" Create a new array called F which is 3-dimensional and contains A in the first column of the third dimension and B in the second column of the third dimension." - where A and B are two previously defined 10x7 matrices.
Thank you for your help, this makes a lot more sense.
julia> A = rand(1:9, 10, 7)
10×7 Matrix{Int64}:
1 3 5 3 5 7 5
4 2 3 8 5 7 7
8 3 6 7 6 5 1
6 2 7 6 9 9 8
3 8 6 8 5 9 8
6 4 6 9 4 4 4
2 6 1 9 5 8 6
6 4 5 4 8 9 7
1 8 3 6 4 7 8
9 3 9 6 8 4 4
julia> B = rand(1:9, 10, 7)
10×7 Matrix{Int64}:
5 1 6 8 6 3 8
4 6 2 9 7 4 4
4 7 5 5 3 7 3
3 3 5 6 3 7 6
4 3 6 1 1 7 8
4 4 2 1 3 3 5
6 4 5 2 1 8 2
4 6 9 8 4 2 4
6 7 5 1 9 6 6
2 9 5 3 5 2 6
julia> C = cat(A, B, dims=3)
10×7×2 Array{Int64, 3}:
[:, :, 1] =
1 3 5 3 5 7 5
4 2 3 8 5 7 7
8 3 6 7 6 5 1
6 2 7 6 9 9 8
3 8 6 8 5 9 8
6 4 6 9 4 4 4
2 6 1 9 5 8 6
6 4 5 4 8 9 7
1 8 3 6 4 7 8
9 3 9 6 8 4 4
[:, :, 2] =
5 1 6 8 6 3 8
4 6 2 9 7 4 4
4 7 5 5 3 7 3
3 3 5 6 3 7 6
4 3 6 1 1 7 8
4 4 2 1 3 3 5
6 4 5 2 1 8 2
4 6 9 8 4 2 4
6 7 5 1 9 6 6
2 9 5 3 5 2 6
Also see the [A ;;; B] syntax which is relatively new.