each / inject / each_with_object

gistfile1.rb

class String
  def count_words
    h = Hash.new(0)
    self.downcase.gsub(/[[:punct:]]/, '').split.each { |w| h[w] += 1 }
    return h
  end
end

#print 'a b c d e a b a a b c d d e f'.count_words #=> {"a"=>4, "b"=>3, "c"=>2, "d"=>3, "e"=>2, "f"=>1}

class String
  def count_words
    self.downcase.gsub(/[[:punct:]]/, '').split.inject(Hash.new(0)) { |h, w| h[w] += 1; h }
  end
end

#print 'a b c d e a b a a b c d d e f'.count_words #=> {"a"=>4, "b"=>3, "c"=>2, "d"=>3, "e"=>2, "f"=>1}

class String
  def count_words
    self.downcase.gsub(/[[:punct:]]/, '').split.each_with_object(Hash.new(0)) { |w, h| h[w] += 1 }
  end
end

#print 'a b c d e a b a a b c d d e f'.count_words #=> {"a"=>4, "b"=>3, "c"=>2, "d"=>3, "e"=>2, "f"=>1}