title: Append empty rows to Dataframe in pandas
body: <p>I want to append empty rows (filled with np.NaN) to a pandas dataframe and currently only know how to do this using loc</p>
  
  <pre><code>T = pd.DataFrame(index=['a', 'b', 'c'], data={'Col0': 0, 'Col1': 1})
  T
     Col0  Col1
  a     0     1
  b     0     1
  c     0     1
  
  missing = ['d', 'e']
  for m in missing:
      T.loc[m] = np.NaN
  
    Col0  Col1
  a   0.0   1.0
  b   0.0   1.0
  c   0.0   1.0
  d   NaN   NaN
  e   NaN   NaN
  </code></pre>
  
  <p>Do you know of a more <em>elegant</em> way to do this?</p>
  
  <p>Why it is not possible to do something like</p>
  
  <pre><code>T.loc[missing] = np.NaN
  </code></pre>
  
  <p>thx!</p>