title: How to select column names in python pandas by dataframe values?
body: <p>I have the following dataframe:</p>
  
  <pre><code>pandas.DataFrame(numpy.random.randn(10, 5) &gt; 1, index=range(1, 11), columns=list('ABCDE'))
  
          A      B      C      D      E
  1   False  False  False  False  False
  2   False  False  False  False  False
  3    True   True  False   True  False
  4   False  False   True   True  False
  5   False  False  False  False  False
  6   False  False  False  False  False
  7   False  False  False  False  False
  8   False  False  False  False  False
  9   False  False  False  False  False
  10  False   True  False   True  False
  </code></pre>
  
  <p>For each row I would like to get the column name that is the last one in that row containing True.
  If there isn't any, return any resonable value.
  How can I do that?</p>