title: error when accessing pandas dataframe index
body: <p>I get an error when trying to access a single element in a pandas dataframe this way test_df["LABEL"][0]. Here is a code snippet on how I am loading the data: </p>
  
  <pre><code>print "reading test set"
  test_set = pd.read_csv(data_path+"small_test_products.txt", header=0, delimiter="|")
  
  print "shape of the test set", test_set.shape 
  test_df = pd.DataFrame(test_set)
  lengthOfTestSet = len(test_df["LABEL"])
  print test_df["LABEL"][0]
  </code></pre>
  
  <p>Here is the error I am getting: </p>
  
  <blockquote>
    <p>File "code.py", line 80, in 
        print test_df["LABEL"][0]   File "/usr/local/lib/python2.7/dist-packages/pandas/core/series.py", line
    521, in <strong>getitem</strong>
        result = self.index.get_value(self, key)   File "/usr/local/lib/python2.7/dist-packages/pandas/core/index.py", line
    3562, in get_value
        loc = self.get_loc(k)   File "/usr/local/lib/python2.7/dist-packages/pandas/core/index.py", line
    3619, in get_loc
        return super(Float64Index, self).get_loc(key, method=method)   File "/usr/local/lib/python2.7/dist-packages/pandas/core/index.py",
    line 1572, in get_loc
        return self._engine.get_loc(_values_from_object(key))   File "pandas/index.pyx", line 134, in pandas.index.IndexEngine.get_loc
    (pandas/index.c:3824)   File "pandas/index.pyx", line 154, in
    pandas.index.IndexEngine.get_loc (pandas/index.c:3704)   File
    "pandas/hashtable.pyx", line 541, in
    pandas.hashtable.Float64HashTable.get_item (pandas/hashtable.c:9914)<br>
    File "pandas/hashtable.pyx", line 547, in
    pandas.hashtable.Float64HashTable.get_item (pandas/hashtable.c:9852)
    KeyError: 0.0</p>
  </blockquote>
  
  <p>What am I missing?</p>