title: Opensource nlp tools for subject/topic tagging
body: <p>Which are good open source tools for subject tagging? I am getting post and comments for each post.</p>
  
  <p>Categories of posts are: <code>Job, discussion, services, events, talent, buy/sell</code> </p>
  
  <p>Some posts would have tags, I need to predict tags for other post. Algorithm should also be able to tag new coming posts.</p>
  
  <p>Each <code>post</code> will have <code>comments</code>, The comments has to be <code>predicted</code> if it is on <code>topic/off-topic</code> or spam.</p>
  
  <p>Tags can be like: <code>marketing, sell, suggestion, entrepreneurship etc</code></p>
  
  <p>There are few NLP tools and librarues  like <code>weka, rapidminer, nlptk, GATE, MOA, KEEL Miner</code>.</p>
  
  <p>But i have not used and dont know which is most suitable. </p>
  
  <p>Any help appreciated : )</p>