title: How to create corpus or corpora for classifying text in NLTK?
body: <p>I'm building a classifier text.</p>
  
  <p>1, Have 10 categories, each category have more relative keywords.
  2, Now, I have a text. I need classify it into one category
  3, I use NLTK but I don't know how to create best train corpus, corpora</p>
  
  <p>Can someone help me with methods to extract features,... tks u</p>