By “it” do you mean the arrays stored as the values in the dictionary? A dictionary is made up of (key, value) pairs:
julia> for (k, v) ∈ pairs(D)
println("Key: ", k, " value: ", v)
end
Key: Field_1 value: [1, 2, 3, 4, 5]
Key: Field_2 value: ["a", "b", "c", "d", "e"]
So if you want to check the number of entries in each array you can do:
julia> length.(values(D))
2-element Vector{Int64}:
5
5
I’m afraid I don’t understand the second question. The first element of each array in your dict is accessed in the same way as computing the length above:
julia> first.(values(D))
2-element Vector{Any}:
1
"a"