I am looking to fill a vector of a desired length up with randomly chosen, unique elements. Currently I have the code below which has the desired effect however, I suspect I can speed it up. If anyone has any ideas it would be appreciated

function randomly_filling_vector(R1, R2, L)
out = [Vector{Int64}(undef,3) for _ in 1:L]
condit = false
while condit == false
for i ∈ eachindex(out)
out[i] = [rand(DiscreteUniform(1, R1)), rand(DiscreteUniform(2, R2-1)), rand(DiscreteUniform(1, 6))]
end
unique = unique!(out)
if length(unique) == L
condit = true
return out
end
end
end

There is a problem with the algorithm you implemented. The line

uses unique! which mutates the out array. This array will get shortened when there are repeating elements in out and subsequently will never be lengthened back, as eachindex(out) in the for earlier will loop over shortened array. Thus the function will enter an infinite loop.

So, first, fixed OP code:

function randomly_filling_vector(R1, R2, L)
out = [Vector{Int64}(undef,3) for _ in 1:L]
condit = false
while condit == false
for i ∈ eachindex(out)
out[i] = [rand(DiscreteUniform(1, R1)), rand(DiscreteUniform(2, R2-1)), rand(DiscreteUniform(1, 6))]
end
uniq = unique(out)
if length(uniq) == L
condit = true
return out
end
end
end

But, as stevengj mentioned, this is work for sample from Random package. The following is an efficient way to implement this:

function randomly_filling_vector2(R1, R2, L)
S = R1*(R2-2)*6
map(sample(1:S, L; replace=false)) do s
d, m = divrem(s, 6)
c3 = m+1
d, m = divrem(d, R2-2)
c2 = m+2
c1 = d+1
[c1, c2, c3]
end
end