title: Error using Stanford POS Tagger in NLTK Python
body: <p>I am trying to use Stanford POS Tagger in NLTK but I am not able to run the example code given here <a href="http://www.nltk.org/api/nltk.tag.html#module-nltk.tag.stanford" rel="noreferrer">http://www.nltk.org/api/nltk.tag.html#module-nltk.tag.stanford</a></p>
  
  <pre><code>import nltk
  from nltk.tag.stanford import POSTagger
  st = POSTagger(r'english-bidirectional-distim.tagger',r'D:/stanford-postagger/stanford-postagger.jar')
  st.tag('What is the airspeed of an unladen swallow?'.split())
  </code></pre>
  
  <p>I have already added environment variables as</p>
  
  <pre><code>CLASSPATH = D:/stanford-postagger/stanford-postagger.jar
  STANFORD_MODELS =  D:/stanford-postagger/models/
  </code></pre>
  
  <p>Here is the error I keep getting</p>
  
  <p>Traceback (most recent call last):</p>
  
  <pre><code>File "D:\pos_stanford.py", line 4, in &lt;module&gt;
      st = POSTagger(r'english-bidirectional-distim.tagger',
           r'D:/stanford-postagger/stanford-postagger.jar')  
  ... LookupError: NLTK was unable to find the english-bidirectional-distim.tagger file! Use software specific configuration paramaters or set the STANFORD_MODELS environment variable.
  </code></pre>
  
  <p>Some forums suggest that </p>
  
  <pre><code>File "C:\Python27\lib\site-packages\nltk\tag\stanford.py", line 45, in __init__
  env_vars=('STANFORD_MODELS'), verbose=verbose)
  </code></pre>
  
  <p>should be changed so that there is a comma in </p>
  
  <pre><code>env_vars=('STANFORD_MODELS',), verbose=verbose)
  </code></pre>
  
  <p>but it doesn't solve the problem either. 
  Please Help me in solving this issue.</p>
  
  <p>Other Information:
  I am using
  Windows 7 64 bit
  Python 2.7 32 bit
  NLTK 2.0</p>