Adding 1d array into 1d array (or Vector?) in mutable structs

Hello everyone! I’m an industrial engineer and relatively new to Julia, so I’m sorry for any possible conceptual mistakes here.

I am interested in creating a vector containing multiple 1d arrays within a mutable structure called “Cell” like the following:

mutable struct Cell
    Sol::Vector{Int16} # This vector should contain multiple 1d arrays

    Cell() = new(0.0, rand(Float16), rand(Float16), 0.0, 0, Vector{Int16}[])

I can properly initialize Cell with a variable called POP:

POP = Cell()

However, I cannot add elements (1d arrays) using push! into POP.Sol, i.e.:

K = Vector{Int16}[[1, 2, 3], [4, 5, 6]]

for i in 1:2 
    push!(POP.Sol, K[i])

The following error message appears: “LoadError: MethodError: Cannot convert an object of type Vector{Int16} to an object of type Int16”. In contrast, doing this is totally fine:

Z = Vector{Int16}[]

for i in 1:2 
    push!(Z, K[i])

Could anyone tell me how could I add the elements of K into POP.Sol such that POP.Sol = [[1, 2, 3], [4, 5, 6]]?

Best wishes!

You want Sol::Vector{Vector{Int16}}

Thanks Oscar!