title: How to get feature names corresponding to scores for chi square feature selection in scikit
body: <p>I am using Scikit for feature selection, but I want to get the score values for all the unigrams in the text. I get the scores, but I how do I map these to actual feature names.</p>
  
  <pre><code>from sklearn.feature_extraction.text  import CountVectorizer
  from sklearn.feature_selection import  SelectKBest, chi2
  
  Texts=["should schools have uniform","schools discipline","legalize marriage","marriage culture"]
  labels=["3","3","7","7"]
  vectorizer = CountVectorizer()
  term_doc=vectorizer.fit_transform(Texts)
  ch2 = SelectKBest(chi2, "all")
  X_train = ch2.fit_transform(term_doc, labels)
  print ch2.scores_
  </code></pre>
  
  <p>This gives the results, but how do I know which feature names maps to what scores?</p>