Word processing for a bayesian spam filter

words.rb

  def process_words
    # Lowercase
    words.each &:downcase!
    # Remove punctuation
    words.map! { |word| word.gsub(/[^a-z0-9\s]/i, '') }
    # Remove numbers
    words.map! { |word| word.gsub(/[0-9]/i, '') }
    # Remove empty and single-letter words
    words.reject! { |word| word.length < 2 }
    # Remove stopwords
    @words -= stopwords
    # Stemming
    words.map! { |word| stemmer.stem(word) }
  end