title: When slicing a 1 row pandas dataframe the slice becomes a series
body: <p>Why when I slice a pandas dataframe containing only 1 row, the slice becomes a pandas series?
  How can I keep it a dataframe?</p>
  
  <pre><code>df=pd.DataFrame(data=[[1,2,3]],columns=['a','b','c'])
  df
  Out[37]: 
     a  b  c
  0  1  2  3
  
  
  a=df.iloc[0]
  
  a
  Out[39]: 
  a    1
  b    2
  c    3
  Name: 0, dtype: int64
  </code></pre>