title: Pandas indexing and Key error
body: <p>Consider the following:</p>
  
  <pre><code>d = {'a': 0.0, 'b': 1.0, 'c': 2.0}
  
  e = pd.Series(d, index = ['a', 'b', 'c'])
  
  df = pd.DataFrame({ 'A' : 1.,'B' : e,'C' :pd.Timestamp('20130102')}).
  </code></pre>
  
  <p>When i try to access the first row of column B in the following way: </p>
  
  <pre><code>&gt;&gt;&gt; df.B[0]
  0.0
  </code></pre>
  
  <p>I get the correct result. </p>
  
  <p>However, after reading <a href="https://stackoverflow.com/questions/46153647/keyerror-0-when-accessing-value-in-pandas-series">KeyError: 0 when accessing value in pandas series</a>, I was under the assumption that, since I have specified the index as 'a', 'b' and 'c', the correct way to access the first row of column B (using positional arguments) is:
  <code>df.B.iloc[0]</code>  , and <code>df.B[0]</code> should raise a Key Error. I dont know what am I missing. Can someone clarify in which case do I get a Key Error ?</p>