title: Find the second largest date in df python
body: <p>Please advise on how to select the second max date in df rows.</p>
  <p>I have a df like this:</p>
  <pre><code>ID   Count   DDate1  DDate2 DDate3 DDate4 DDate5
  </code></pre>
  <p>Columns with <code>ddate</code> are converted to datetime.
  The max value I have found in this way:</p>
  <pre><code>cols_1 = df_deal_employee.columns[2:6]
  df['max_date'] = df[cols_1].max(1)
  </code></pre>
  <p>But can I create a column with the following max date? (second largest).</p>