Elixer Genetic Algorithm

Section

# One max problem in elixir
population = for _ <- 1..100, do: for(_ <- 1..1000, do: Enum.random(0..1))

evaluate = fn population ->
  Enum.sort_by(population, &amp;Enum.sum/1, &amp;>=/2)
end

# select parents, create list of tuples 
selection = fn population ->
  population
  |> Enum.chunk_every(2)
  |> Enum.map(&amp;List.to_tuple(&amp;1))
end

# analogous to reproduction
crossover = fn population ->
  # pattern match inside Enum.reduce/3
  Enum.reduce(population, [], fn {p1, p2}, acc ->
    cx_point = :rand.uniform(1000)
    {{h1, t1}, {h2, t2}} = {Enum.split(p1, cx_point), Enum.split(p2, cx_point)}
    [h1 ++ t2, h2 ++ t1 | acc]
  end)
end

mutation = fn population ->
  population
  |> Enum.map(fn chromosome ->
    if :rand.uniform() < 0.05 do
      Enum.shuffle(chromosome)
    else
      chromosome
    end
  end)
end

algorithm = fn population, algorithm ->
  best = Enum.max_by(population, &amp;Enum.sum/1)
  IO.write("\rCurrent Best: " <> Integer.to_string(Enum.sum(best)))

  if Enum.sum(best) == 1000 do
    best
  else
    # Initial population
    population
    # Evaluate population
    |> evaluate.()
    # Select parents
    |> selection.()
    # Create children 
    |> crossover.()
    # Mutation
    |> mutation.()
    # Repeat process with new population
    |> algorithm.(algorithm)
  end
end

solution = algorithm.(population, algorithm)
IO.write("\n Answer is \n")
IO.inspect(solution)

Current Best: 1000
 Answer is 
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, ...]

[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, ...]

population = for _ <- 1..100, do: for(_ <- 1..1000, do: Enum.random(0..1))

[
  [1, 0, 1, 1, 0, 0, 0, 1, 0, 1, 1, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 1, 0, 1, 0,
   1, 1, 1, 0, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 1, 1, 0, ...],
  [1, 1, 0, 1, 0, 0, 0, 0, 1, 1, 0, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1,
   1, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, ...],
  [1, 1, 0, 0, 1, 0, 1, 1, 1, 1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 1, 0, 0, 1, 1, 1, 0, 0, 0, 1,
   0, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, ...],
  [0, 1, 1, 0, 1, 1, 0, 1, 0, 1, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 1, 0, 1,
   1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, ...],
  [0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 0, 0, 1, 1, 1, 1, 0, 1,
   1, 0, 1, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, ...],
  [1, 0, 1, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 1, 1, 1,
   0, 0, 0, 0, 1, 1, 0, 1, 1, 0, 0, 0, ...],
  [1, 1, 1, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 0, 0,
   0, 1, 0, 1, 1, 0, 0, 1, 0, 0, 0, ...],
  [1, 1, 1, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 0, 1, 1, 0, 1, 0, 0,
   0, 0, 1, 0, 1, 1, 1, 0, 0, 0, ...],
  [1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 0, 1,
   0, 0, 1, 1, 0, 1, 0, 0, 0, ...],
  [1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 0, 1, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0,
   0, 0, 0, 0, 0, 0, 1, 0, ...],
  [0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 1, 1, 1, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 0, 1, 0, 1, 1,
   1, 0, 1, 1, 0, 1, 0, ...],
  [1, 0, 0, 1, 0, 1, 0, 1, 0, 0, 1, 1, 1, 0, 0, 0, 0, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0, 1, 1, 0, 1, 1,
   0, 0, 1, 1, 1, 0, ...],
  [0, 0, 1, 1, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0,
   0, 0, 0, 0, 1, ...],
  [1, 0, 0, 0, 1, 1, 0, 0, 1, 1, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1,
   1, 0, 1, 0, ...],
  [1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1,
   0, 1, 0, ...],
  [1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0,
   1, 1, ...],
  [1, 1, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 0, 1, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1,
   0, ...],
  [1, 1, 1, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 0, 1, 0, 1, 1, 0, 1,
   ...],
  [0, 1, 1, 0, 1, 0, 1, 1, 1, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, ...],
  [0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 1, 1, ...],
  [1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, ...],
  [1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, ...],
  [0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, ...],
  [1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 0, ...],
  [0, 1, 1, 1, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 1, 1, 1, ...],
  [0, 1, 1, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, ...],
  [1, 0, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 0, 1, 1, 0, 0, 1, 1, 1, 0, 1, 1, ...],
  [1, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, ...],
  [0, 0, 0, 1, 0, 1, 1, 1, 1, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, ...],
  [1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 1, 0, ...],
  [1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 1, 1, 1, ...],
  [0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 0, 1, 0, 1, 1, 0, 0, 1, ...],
  [1, 1, 0, 1, 0, 1, 1, 0, 0, 1, 0, 1, 0, 1, 1, 1, 1, ...],
  [0, 1, 1, 0, 1, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, ...],
  [1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, ...],
  [0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 1, ...],
  [1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, ...],
  [0, 1, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, ...],
  [0, 1, 0, 1, 0, 0, 0, 1, 1, 0, 0, ...],
  [1, 1, 1, 1, 0, 0, 0, 0, 1, 1, ...],
  [1, 0, 1, 1, 1, 0, 1, 0, 0, ...],
  [0, 1, 1, 1, 1, 1, 0, 1, ...],
  [0, 0, 0, 1, 0, 0, 0, ...],
  [0, 0, 1, 1, 1, 0, ...],
  [0, 0, 0, 1, 1, ...],
  [1, 0, 0, 0, ...],
  [1, 0, 0, ...],
  [1, 0, ...],
  [1, ...],
  [...],
  ...
]

:rand.uniform(1000)

595