title: How to get values from a "cell" of a "groupby" object?
body: <p>Assume that I have the following data frame:</p>
  
  <pre><code>     A    B  C   D
  0  foo  one  1  10
  1  bar  one  2  20
  2  foo  two  3  30
  3  bar  one  4  40
  4  foo  two  5  50
  5  bar  two  6  60
  6  foo  one  7  70
  7  foo  two  8  80
  </code></pre>
  
  <p>Now I can group by the first column: <code>grouped = df.groupby('A')</code>. As a result I get the following <code>DataFrameGroupBy</code> object:</p>
  
  <pre><code>     A            B                 C              D
  0  foo  [one,two,two,one,two]  [1,3,5,7,8]  [10,30,50,70,80]
  1  bar  [one,one,two]          [2,4,6]      [20,40,60]
  </code></pre>
  
  <p>Now I would like to access the values from a particular cell. How can I do it? For example I want to get the values from the column 'D' and the row where <code>'A'=='foo'</code> (the first row). In other words I want to get <code>[10,30,50,70,80]</code>. Is it possible?</p>