Julia equivalent to python list multiplication-CodePudding

In python I can quickly concatenate and create lists with repeated elements using the and * operators. For example:

my_list = [1] * 3   ['a'] * 4  # == [1, 1, 1, 'a', 'a', 'a', 'a']

Similarly in Julia, I can quickly concatenate and create strings with repeated elements using the * and ^ operators. For example:

my_string = "1"^3 * "a"^4  # == "111aaaa"

My question is whether or not there is a convenient equivalent for lists (arrays) in Julia. If not, then what is the simplest way to define arrays with repeated elements and concatenation?

CodePudding user response：

You can use repeat, e.g.

[repeat([1], 3); repeat(['a'],4)]

produces Any[1, 1, 1, 'a', 'a', 'a', 'a'].

CodePudding user response：

For the above scenario, a shorter form is fill:

[fill(1,3); fill('a', 4)]

You could also define a Python style operator if you like:

⊕(a::AbstractVector{T}, n::Integer) where T = repeat(a, n)
⊕(a::T, n::Integer) where T = fill(a, n)

The symbol ⊕ can be entered in Julia by typing \oplus and pressing Tab.

Now you can do just as in Python:

julia> [1,2] ⊕ 2
4-element Vector{Int64}:
 1
 2
 1
 2

julia> 3 ⊕ 2
2-element Vector{Int64}:
 3
 3