# Wakaway

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

## Installation

If [available in Hex](https://hex.pm/docs/publish), 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

```elixir
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

```elixir
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.

```elixir
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](https://github.com/ikeikeikeike/wakaway/blob/master/test/wakaway_test.exs)