redis_index.rb

#
# poor man's text index
#
# a simple ruby implementation of the idea descibed in:
#   http://playnice.ly/blog/2010/05/05/a-fast-fuzzy-full-text-index-using-redis/
#
require 'rubygems'
require 'text'
require 'set'
require 'redis'

class Item
  attr_accessor :id, :txt
 
  def initialize(id, txt)
    @id = id
    @txt = txt
  end
end

class FullTextIndex

  def initialize
    @stopwords = ["the", "of", "to", "and", "a", "in", "is", "it", "you", "that"]
    @redis = Redis.new
  end

  def get_words_from_text(text)
    words = text.split(/[^a-zA-Z]/)
    return words - @stopwords
  end

  def get_metaphones(words)
    metaphones = Set.new
    words.each do |word|
      m = Text::Metaphone.double_metaphone(word)
      metaphones.add(m)
    end
		return metaphones
  end

  def index_item(item)
    words = get_words_from_text(item.txt)
    metaphones = get_metaphones(words)

    metaphones.each do |metaphone|
      _link_item_and_metaphone(item, metaphone)
    end
  end

  def _link_item_and_metaphone(item, metaphone)
    @redis.sadd("metaphone:#{metaphone}", item.id)
  end

end

item1 = Item.new(1, "hello my name is john")
item2 = Item.new(2, "hello my name is mary")
myindex = FullTextIndex.new
myindex.index_item(item1)
myindex.index_item(item2)