Comprehensions in Julia
Code
In Julia, like in Python, comprehension is possible. Comprehension is a method of creating arrays that involves embedding conditional expressions directly into the array.
For instance, if you want to define an array containing integers sequentially from $0$ to $9$, you can embed a for loop directly into the array.
julia> [i for i ∈ 0:9]
10-element Vector{Int64}:
0
1
2
3
4
5
6
7
8
9
julia> [i*ones(8) for i ∈ 1:9]
9-element Vector{Vector{Float64}}:
[1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0]
[2.0, 2.0, 2.0, 2.0, 2.0, 2.0, 2.0, 2.0]
[3.0, 3.0, 3.0, 3.0, 3.0, 3.0, 3.0, 3.0]
[4.0, 4.0, 4.0, 4.0, 4.0, 4.0, 4.0, 4.0]
[5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0]
[6.0, 6.0, 6.0, 6.0, 6.0, 6.0, 6.0, 6.0]
[7.0, 7.0, 7.0, 7.0, 7.0, 7.0, 7.0, 7.0]
[8.0, 8.0, 8.0, 8.0, 8.0, 8.0, 8.0, 8.0]
[9.0, 9.0, 9.0, 9.0, 9.0, 9.0, 9.0, 9.0]
julia> stack([i*ones(8) for i ∈ 1:9], dims=2)
8×9 Matrix{Float64}:
1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0
1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0
1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0
1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0
1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0
1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0
1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0
1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0
Nested for loops are also possible.
julia> X = 1:4
1:4
julia> Y = [-1, 0, 1]
3-element Vector{Int64}:
-1
0
1
julia> [x*y for x=X, y=Y]
4×3 Matrix{Int64}:
-1 0 1
-2 0 2
-3 0 3
-4 0 4
Environment
- OS: Windows11
- Version: Julia 1.10.0