title: ValueError: empty vocabulary; perhaps the documents only contain stop words
body: <p>I'm using (for the first time) the scikit library and I got this error:</p>
  
  <pre><code>ValueError: empty vocabulary; perhaps the documents only contain stop words
  File "C:\Users\A605563\Desktop\velibProjetPreso\TraitementTwitterDico.py", line 33, in &lt;module&gt;
  X_train_counts = count_vect.fit_transform(FileTweets)
  File "C:\Python27\Lib\site-packages\sklearn\feature_extraction\text.py", line 804, in fit_transform
  self.fixed_vocabulary_)
  File "C:\Python27\Lib\site-packages\sklearn\feature_extraction\text.py", line 751, in _count_vocab
  raise ValueError("empty vocabulary; perhaps the documents only contain stop words
  </code></pre>
  
  <p>But I don't understand why that's happening.</p>
  
  <pre><code>import sklearn
  from sklearn.feature_extraction.text import CountVectorizer
  import pandas as pd
  import numpy
  import unicodedata
  import nltk
  
  
  TweetsFile = open('tweets2015-08-13.csv', 'r+')
  f2 = open('analyzer.txt', 'a')
  print TweetsFile.readline()
  count_vect = CountVectorizer(strip_accents='ascii')
  FileTweets =  TweetsFile.read()
  FileTweets = FileTweets.decode('latin1')
  FileTweets = unicodedata.normalize('NFKD', FileTweets).encode('ascii','ignore')
  print FileTweets
  for line in TweetsFile:
      f2.write(line.replace('\n', ' '))
  TweetsFile = f2
  print type(FileTweets)
  X_train_counts = count_vect.fit_transform(FileTweets)
  print X_train_counts.shape
  TweetsFile.close()
  </code></pre>
  
  <p>My data is raw tweets: </p>
  
  <pre><code>11/8/2015 @ Paris Marriott Champs Elysees Hotel "
  2015-08-11 21:27:15,"I'm at Paris Marriott Hotel Champs-Elysees in Paris, FR &lt;https://t.co/gAFspVw6FC&gt;"
  2015-08-11 21:24:08,"I'm at Four Seasons Hotel George V in Paris, Ile-de-France &lt;https://t.co/dtPALvziWy&gt;"
  2015-08-11 21:22:11,    . @ Avenue des Champs-Elysees &lt;https://t.co/8b7U05OAxG&gt;
  2015-08-11 20:54:18,Her pistol go @ Raspoutine Paris (Official) &lt;https://t.co/le9l3dtdgM&gt;
  2015-08-11 20:50:14,"Desde Paris, con amor. @ Avenue des Champs-Elysees &lt;https://t.co/R68JV3NT1z&gt;"
  </code></pre>
  
  <p>Does anybody know what's happening here?</p>