Wakaway

There're Walker's Alias Method and Weighted Choice that providing weighted random choice algorism in two ways.

Installation

If available in Hex, the package can be installed as:

1. Add wakaway to your list of dependencies in mix.exs:

```elixir
def deps do
  [{:wakaway, "~> 0.5.0"}]
end
```

Usage

WalkersAliasMethod

alias Wakaway.WalkersAliasMethod

resource =
  WalkersAliasMethod.resource(
    [1, 2, 3, 50, 100, 200],
    [1, 2, 3, 50, 100, 200]
  )

# resource =
#   [s100: 100, s200: 200, s50: 50, s3: 3, s2: 2, s1: 1,]
#   |> WalkersAliasMethod.resource

# resource =
#   %{100 => 100, 200 => 200, 50 => 50, 3 => 3, 2 => 2, 1 => 1}
#   |> WalkersAliasMethod.resource

result =
  Enum.map(0..50, fn _ ->
    WalkersAliasMethod.choice(resource)
  end)
  |> Enum.sort(&(&1 > &2))

IO.inspect result
# [200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200,
#  200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200,
#  200, 200, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 50, 50, 50, 50, 50,
#  50, ...]

WeightedChoice

alias Wakaway.WeightedChoice

resource =
  WeightedChoice.resource(
    [1, 2, 3, 50, 100, 200],
    [1, 2, 3, 50, 100, 200]
  )

# resource =
#   [s100: 100, s200: 200, s50: 50, s3: 3, s2: 2, s1: 1,]
#   |> WeightedChoice.resource

# resource =
#   %{100 => 100, 200 => 200, 50 => 50, 3 => 3, 2 => 2, 1 => 1}
#   |> WeightedChoice.resource

result = Enum.map(0..50, fn _ ->
    WeightedChoice.choice(resource)
  end)
  |> Enum.sort(&(&1 > &2))

IO.inspect result
# [200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200,
#  200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200,
#  200, 200, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 50, 50, 50, 50, 50,
#  50, ...]

Simple ways

NOTE: This examples are slower than above way when they are called by users a lot of times.

iex(1)> item = %{100 => 100, 200 => 200, 50 => 50, 3 => 3, 2 => 2, 1 => 1}
%{1 => 1, 2 => 2, 3 => 3, 50 => 50, 100 => 100, 200 => 200}
iex(2)> Wakaway.walker_choice(item)
200
iex(3)> Wakaway.weighted_choice(item)
100

Example more