Alek Ratzloff
6d503089e4
For some reason there doesn't appear to be a binary search function in Elixir's standard library, so this implements that. Signed-off-by: Alek Ratzloff <alekratz@gmail.com>
36 lines
1.2 KiB
Elixir
36 lines
1.2 KiB
Elixir
defmodule Omnibot.Contrib.Markov.Chain do
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alias Omnibot.{Contrib.Markov.Chain, Util}
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@enforce_keys [:order]
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defstruct order: 2, chain: []
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def train(%Chain {chain: chain, order: order}, words) when is_list(words) do
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Enum.filter(words, &(String.length(&1) > 0))
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|> Enum.chunk_every(order + 1, 1) # this gives us a "sliding window" effect
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|> Enum.reduce(chain, &case Enum.split(words, order) do
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{words, []} -> if length(&1) == order,
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# Null case for the chain; this is an "end" state
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do: train_one(%Chain {chain: &2, order: order}, words, nil)
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# else: TODO ? train [a, nil] -> b ?
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{words, [next]} ->
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train_one(%Chain {chain: &2, order: order}, words, next)
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end
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)
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end
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def train_one(%Chain {chain: _chain, order: _order}, _key, _value) do
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end
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def lookup(%Chain {chain: chain, order: order}, key) do
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if length(key) != order, do: raise(ArgumentError, message: "invalid key (length #{length(key)} vs. order #{order})")
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case Util.binary_search(chain, key) do
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{_index, value} -> value
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nil -> nil
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end
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end
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def put(%Chain {chain: _chain, order: _order}, _key, _value) do
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end
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end
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