title: pandas add row instead of column
body: <p>I'm new to pandas, but trying to simply add a row</p>
  
  <pre><code>class Security:
      def __init__(self):
          self.structure = ['timestamp', 'open', 'high', 'low', 'close', 'vol']
          self.df = pd.DataFrame(columns=self.structure)  # index =
      def whats_inside(self):
          return self.df
      """
      Some skipped code...
      """
      def add_data(self, timestamp, open, high, low, close, vol):
          data = [timestamp, open, high, low, close, vol]
          self.df = self.df.append (data)
  
  sec = Security()
  print sec.whats_inside()
  sec.add_data ('2015/06/01', '1', '2', '0.5', '1', '100')
  print sec.whats_inside()
  </code></pre>
  
  <p>but the output is:</p>
  
  <pre><code>            0 close high  low open timestamp  vol
  0  2015/06/01   NaN  NaN  NaN  NaN       NaN  NaN
  1           1   NaN  NaN  NaN  NaN       NaN  NaN
  2           2   NaN  NaN  NaN  NaN       NaN  NaN
  3         0.5   NaN  NaN  NaN  NaN       NaN  NaN
  4           1   NaN  NaN  NaN  NaN       NaN  NaN
  5         100   NaN  NaN  NaN  NaN       NaN  NaN
  </code></pre>
  
  <p>This means, I'm adding a column instead of row. Yes, I've tried to google but still didnt get the point how do make it simple pythonic way.</p>
  
  <p>p.s. I know that's simple, but I'm just missing something important.</p>