long_hair.rb

require 'matrix'
require 'tf-idf-similarity'

class Token
  def initialize(mecab_node)
    @node = mecab_node
  end

  def valid?
    @node.feature.start_with?('名詞')
  end

  def to_s
    @node.surface
  end
end

class Tokenizer
  def tokenize(text)
    require 'natto'

    nm = Natto::MeCab.new

    nm.enum_parse(text).to_a.map do |node|
      Token.new(node)
    end
  end
end

tokenizer = Tokenizer.new
options = { tokenizer: tokenizer }

document1 = TfIdfSimilarity::Document.new("ロン毛", options)
document2 = TfIdfSimilarity::Document.new("セミロン毛", options)
document3 = TfIdfSimilarity::Document.new("セミ", options)

corpus = [document1, document2, document3]
model = TfIdfSimilarity::TfIdfModel.new(corpus)

matrix = model.similarity_matrix

puts matrix

#=> Matrix[[0.9999999999999999, 0.3360969272762574, 0.0], [0.3360969272762574, 0.9999999999999999, 0.0], [0.0, 0.0, 1.0]]