Identify related articles based on similar tags in article tags sets

related_articles_help.rb

def related_articles
  articles = []
  if item[:tags] != nil
    tags = item[:tags].split(",")
    tags = tags.collect {|tag| tag.downcase.strip}
    # Iterate over the all the tags and collect the articles
    # with the same tags. If the article shares more than one tag then
    # weight the article.
    tags.each do |tag|
      (@items - [item]).each do |item|
        if item[:tags]
          other_tags = item[:tags].split(",")
          other_tags = other_tags.collect {|tag| tag.downcase.strip}
          if other_tags != nil and other_tags.include? tag
            article = (articles.select { |a| a[:item] == item }).first
            if article == nil
              article = { :item => item }
              articles << article
            end
            article[:count] = (article[:count] || 0) + 1
          end
        end
      end
    end
    # Sort the articles list by the number of tags they share
    articles.sort! { |a, b| b[:count] <=> a[:count] }
    # Ignore any items which don't share more than two tags
    articles.reject! { |a| a[:count] < 2 }
    # Only return the items
    articles.collect! { |a| a[:item] }
  end
  articles
end