Alek Ratzloff
9c69ca7b72
* Markov chains record words correctly from a single line to the end of their line with a couple of exceptions. * Start working on using ETS for storing markov chains, and saving it as a DETS periodically Signed-off-by: Alek Ratzloff <alekratz@gmail.com>
40 lines
1.3 KiB
Elixir
40 lines
1.3 KiB
Elixir
defmodule Omnibot.Contrib.Markov.Chain do
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alias Omnibot.Contrib.Markov.Chain
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@enforce_keys [:order]
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defstruct order: 2, chain: []
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def train(chain, line) when is_binary(line) do
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train(chain, line |> String.split(~r/\s+/))
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end
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def train(chain, words) when is_list(words) do
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order = chain.order
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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(&1, order) do
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{words, []} -> if length(words) == order,
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# Null case for the chain; this is an "end" state
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do: add_weight(&2, words, nil),
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else: &2 # TODO ? train [a, nil] -> b ?
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{words, [next]} -> add_weight(&2, words, next)
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end)
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end
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def add_weight(%Chain {chain: chain, order: order}, key, word, increment \\ 1) 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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chain = case Enum.find_index(chain, fn {listkey, _} -> listkey == key end) do
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# Insert weight
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nil -> [{key, %{word => increment}} | chain]
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# Update weight
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index -> List.update_at(
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chain,
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index,
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fn {key, mapping} -> {key, Map.update(mapping, word, increment, &(&1 + increment))} end
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)
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end
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%Chain{chain: chain, order: order}
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end
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end
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