title: Get first row value of a given column
body: <p>This seems like a ridiculously easy question... but I'm not seeing the easy answer I was expecting.</p>
  <p>So, how do I get the value at an nth row of a given column in Pandas? (I am particularly interested in the first row, but would be interested in a more general practice as well).</p>
  <p>For example, let's say I want to pull the 1.2 value in <code>Btime</code> as a variable.</p>
  <p>Whats the right way to do this?</p>
  <pre class="lang-py prettyprint-override"><code>&gt;&gt;&gt; df_test
      ATime   X   Y   Z   Btime  C   D   E
  0    1.2  2  15   2    1.2  12  25  12
  1    1.4  3  12   1    1.3  13  22  11
  2    1.5  1  10   6    1.4  11  20  16
  3    1.6  2   9  10    1.7  12  29  12
  4    1.9  1   1   9    1.9  11  21  19
  5    2.0  0   0   0    2.0   8  10  11
  6    2.4  0   0   0    2.4  10  12  15
  </code></pre>