title: how to select table column by column header name with xpath
body: <p>I have a table of results and it looks like following:</p>
  
  <pre class="lang-xhtml prettyprint-override"><code>&lt;table&gt;
    &lt;thead&gt;
      &lt;tr&gt;
        &lt;th&gt;Id&lt;/th&gt;
        &lt;th&gt;Type&lt;/th&gt;
        &lt;th&gt;Amount&lt;/th&gt;
        &lt;th&gt;Price&lt;/th&gt;
        &lt;th&gt;Name&lt;/th&gt;
        &lt;th&gt;Expiration&lt;/th&gt;
      &lt;/tr&gt;
    &lt;/thead&gt;
    &lt;tbody&gt;
      &lt;tr&gt;
        &lt;td&gt;123&lt;/td&gt;
        &lt;td&gt;Paper&lt;/td&gt;
        &lt;td&gt;10 pcs.&lt;/td&gt;
        &lt;td&gt;$10&lt;/td&gt;
        &lt;td&gt;Premium Copier paper&lt;/td&gt;
        &lt;td&gt;None&lt;/td&gt;
      &lt;/tr&gt;
      &lt;tr&gt;
        &lt;td&gt;321&lt;/td&gt;
        &lt;td&gt;Paper&lt;/td&gt;
        &lt;td&gt;20 pcs.&lt;/td&gt;
        &lt;td&gt;$20&lt;/td&gt;
        &lt;td&gt;Extra Copier paper&lt;/td&gt;
        &lt;td&gt;None&lt;/td&gt;
      &lt;/tr&gt;
    &lt;/tbody&gt;
  </code></pre>
  
  <p>And i want to select the whole column by its name with xpath e.g. i want the returned result to be an array of <code>{&lt;td&gt;$10&lt;/td&gt;, &lt;td&gt;$20&lt;/td&gt;}</code> if selected by column name "Price".
  I'm new to xpath and not really sure how to do this, but i'm pretty sure it's possible.</p>