title: How can I change a specific row label in a Pandas dataframe?
body: <p>I have a dataframe such as:</p>
  
  <pre><code>      0     1    2    3    4    5
  0  41.0  22.0  9.0  4.0  2.0  1.0
  1   6.0   1.0  2.0  1.0  1.0  1.0
  2   4.0   2.0  4.0  1.0  0.0  1.0
  3   1.0   2.0  1.0  1.0  1.0  1.0
  4   5.0   1.0  0.0  1.0  0.0  1.0
  5  11.4   5.6  3.2  1.6  0.8  1.0
  </code></pre>
  
  <p>Where the final row contains averages. I would like to rename the final row label to <code>"A"</code> so that the dataframe will look like this:</p>
  
  <pre><code>      0     1    2    3    4    5
  0  41.0  22.0  9.0  4.0  2.0  1.0
  1   6.0   1.0  2.0  1.0  1.0  1.0
  2   4.0   2.0  4.0  1.0  0.0  1.0
  3   1.0   2.0  1.0  1.0  1.0  1.0
  4   5.0   1.0  0.0  1.0  0.0  1.0
  A  11.4   5.6  3.2  1.6  0.8  1.0
  </code></pre>
  
  <p>I understand columns can be done with <code>df.columns = . . .</code>. But how can I do this with a specific row label?</p>